Short answer: This 7-point stress test takes about 30 minutes, costs nothing, and tells you whether your AC is ready for a Las Vegas summer — or whether it's going to fail on the worst possible day. You need a thermometer, a phone timer, and a flashlight. Each test gives you a clear pass/fail result, and each failure points to a specific problem you can address now instead of in July when you're waiting three days for a technician. If you'd rather have a professional run a comprehensive diagnostic, call The Cooling Company at (702) 567-0707 or book online.
Key Takeaways
- This is a self-assessment, not a replacement for professional maintenance. These 7 tests reveal the most common warning signs that your system is heading toward failure. They help you decide whether you need a pro now, soon, or not until your next scheduled tune-up.
- Test #1 — the temperature split — catches 60% of problems by itself. If the difference between your supply and return air is outside the 15–20°F range, something is wrong. You don't need to know what — that single number tells you enough to pick up the phone.
- March 2026 is already breaking heat records. The March 2026 heat wave pushed temperatures near 100°F weeks ahead of schedule. The maintenance window is closing faster than any year in recent memory.
- 70% of emergency AC calls in summer trace back to problems that were detectable weeks or months earlier. A clogged filter, a short-cycling compressor, a 3°F thermostat drift — all discoverable in 30 minutes with these tests.
- Every test result includes a clear action plan. Pass means peace of mind. Marginal means schedule maintenance soon. Fail means call a professional before the first 110°F day.
- You don't need to be an HVAC technician. I've taught this test to hundreds of customers. If you can read a thermometer, hold a tissue near a vent, and listen, you can do this.
Why You Need to Stress Test Your AC Now — Not in June
I want to be direct with you. Your air conditioner might be running right now. It might be blowing cool air. And it still might not survive July.
Here's why: in mild weather — 85°F, 90°F — even a struggling system can keep your house comfortable. A system that's a pound low on refrigerant, or has a capacitor at 80% strength, or a condenser coil that's 20% clogged with desert dust will still cool your house when it's 88 degrees outside. You won't notice anything wrong.
But when the valley hits 112°F, 115°F, 118°F — and it will — that same system hits a wall. The refrigerant can't absorb enough heat. The capacitor can't start the compressor reliably. The dirty coil can't reject heat fast enough. And the system that "worked fine in April" fails at 3 p.m. on the hottest day of the year, when every HVAC company in the valley has a four-day wait list.
I've been working on air conditioners in this valley for over three decades, and this pattern repeats every single summer. The homeowners who run through these seven checks in the spring are the ones who don't call us in a panic in July. The ones who assume "it was working last time I turned it on" are the ones sweating in a 95°F house, calling every contractor in the phone book.
The March 2026 heat wave already compressed the maintenance window. We're seeing near-100°F days right now — temperatures that normally don't arrive until late May. That means the clock is already ticking. If your system has a hidden problem, you want to find it today, not when the thermometer reads 115.
What You'll Need
This entire stress test requires three things you probably already have:
- A thermometer — a cheap digital cooking thermometer works perfectly. An infrared (point-and-shoot) thermometer is even better if you have one.
- A phone timer or stopwatch — the timer on your phone is fine.
- A flashlight — for inspecting the outdoor unit and the filter.
Total time: about 30 minutes. Total cost: nothing.
Let's go.
Test #1: The Temperature Split Test (The Single Most Important Check)
If you only do one test from this entire article, do this one. The temperature split test tells you, in a single number, whether your AC is actually cooling at the level it's supposed to. I run this test on every service call I make. It's the first thing our technicians check. And you can do it with a $12 kitchen thermometer.
What It Measures
The temperature split (also called delta-T) is the difference between the air going into your system and the air coming out. Your AC absorbs heat from the return air, runs it across the cold evaporator coil, and pushes cooled air out through the supply vents. The temperature difference between those two points tells you how effectively the system is transferring heat.
How to Do It
- Set your thermostat to COOL mode, 5°F below the current indoor temperature. This ensures the system is running at full capacity, not just idling.
- Wait 15 minutes. The system needs time to stabilize. Readings taken in the first few minutes after startup are unreliable.
- Measure the supply air temperature. Hold your thermometer directly in the airflow at the supply vent closest to your indoor air handler. That's the vent where conditioned air comes out — usually a ceiling or wall register. You want the vent nearest to the unit to minimize duct losses.
- Measure the return air temperature. Hold your thermometer at the return vent — that's the large grille, usually near the filter, where air gets pulled back into the system. If your filter is in a hallway ceiling grille, that's your return.
- Calculate the difference. Supply air at 58°F, return air at 76°F — that's an 18°F split.
What the Results Mean
| Temperature Split | What It Means | Action |
|---|---|---|
| 15–20°F | System is cooling properly. Heat transfer is within normal range. | Pass — no immediate action needed. |
| 10–14°F | System is underperforming. Could be low refrigerant, dirty evaporator coil, or airflow restriction. | Schedule professional maintenance within 2–4 weeks. |
| Under 10°F | Serious cooling problem. The system is barely removing heat from the air. Possible causes: significantly low refrigerant, failed compressor valve, major coil blockage. | Call a professional. Do not wait for summer. |
| Over 22°F | Split is too high — usually means airflow is restricted. Common causes: dirty filter, closed vents, collapsed ductwork, undersized return. | Check filter and vents first. If those are fine, schedule a diagnostic. |
Why This Test Is So Powerful
This single measurement catches the majority of problems that cause mid-summer failures. Low refrigerant? Shows up as a low split. Dirty coils? Low split. Failing compressor? Low split. Clogged filter? High split. Duct problems? Uneven split between rooms.
I tell homeowners: if you get a solid 15–20°F split, your system is doing its primary job. It doesn't mean nothing else could be wrong, but the core cooling function is working. If you're outside that range — especially under 10°F — that's beyond DIY territory. Something specific is failing, and a technician with gauges and diagnostic tools needs to identify what.
For a deeper understanding of how extreme heat pushes these numbers to their limits, read our breakdown of how 120°F summers destroy AC components.
Test #2: The Airflow Check
Airflow is the delivery mechanism for everything your AC does. Your system could be producing perfectly cold air at the evaporator coil, but if that air isn't reaching the rooms in your house, you'll be hot — and the system will be under stress.
This test takes five minutes and requires nothing but a tissue or a thin piece of paper.
How to Do It
Walk through every room in your house. At each supply register (the vents where air blows out), hold a tissue or a single-ply piece of paper near the vent.
Check for:
- Is air actually coming out? The tissue should blow away from the vent noticeably. If it barely moves or doesn't move at all, that register has an airflow problem.
- Are any vents closed or blocked? Check the damper lever on the vent face. Look for furniture, drapes, rugs, or storage boxes placed over or against vents.
- Is airflow roughly equal between rooms? You're not looking for laboratory precision. You're looking for one room that's dramatically weaker than the others.
- Are any rooms noticeably warmer than the rest? Walk the house and feel the difference. Upstairs rooms will always be slightly warmer (heat rises), but a 5°F+ difference between rooms on the same floor indicates a problem.
What the Results Mean
| Finding | Likely Cause | Action |
|---|---|---|
| Strong, consistent airflow from all vents | Ductwork is intact and unobstructed | Pass — no action needed. |
| One room has zero or very weak airflow | Disconnected flex duct, crushed duct run, or closed damper in the duct system | Check if the vent damper is open. If it is, you likely have a duct problem — call for inspection. |
| All rooms have weak airflow | Blower motor issue, severely clogged filter, or collapsed main trunk line | Check the filter first (see Test #4). If the filter is clean, schedule a blower motor and duct inspection. |
| Upstairs is 5–8°F warmer than downstairs | Normal in Las Vegas two-story homes, but may indicate duct leaks in the attic, insufficient insulation, or an undersized system | Manageable with thermostat adjustments, but worth mentioning at your next maintenance visit. |
| Multiple vents are closed | Someone closed them — possibly based on the myth that closing vents saves energy | Open them. All of them. Right now. |
The "Closing Vents Saves Energy" Myth
I need to address this directly because I encounter it on at least two service calls every week. Closing supply vents in unused rooms does not save energy. It increases static pressure in the duct system, forces the blower motor to work harder, reduces total airflow across the evaporator coil, and can cause the coil to freeze.
Your system was designed and sized to push a specific volume of air through a specific number of vents. When you close some of those vents, you're not reducing the system's workload — you're restricting its ability to do its job. Open every vent in the house and leave them open.
If one or more rooms have genuine duct problems — disconnected runs, crushed flex duct in the attic, or damaged insulation — that's a professional repair. In Las Vegas attics, where temperatures reach 150°F+, duct tape and flex duct connections deteriorate faster than in moderate climates. It's worth having a technician inspect the ductwork during your next maintenance visit.
Test #3: The Outdoor Unit Inspection
Your condenser unit is the workhorse of the system. It sits outside, exposed to the desert environment 24/7, and its job is to dump the heat your house doesn't want into the outdoor air. If the condenser can't do its job, nothing else matters — the system can't cool.
This inspection takes five minutes. Grab your flashlight and walk outside.
The Checklist
Clearance:
- Is there at least 2 feet of open space on all sides of the unit? No bushes, no patio furniture, no storage bins, no decorative lattice, no trash cans.
- Is there at least 4 feet of clearance above the unit? No awning or patio cover directly on top (shade from above is fine if it doesn't restrict upward airflow from the fan).
Vegetation:
- Have any plants, shrubs, or ground cover grown into the clearance zone since last fall? Desert landscaping grows aggressively in spring. Trim anything within 2 feet.
Coil Condition:
- Look at the aluminum fins on the sides of the unit. Are they clean and straight, or are they matted with dust, cottonwood fluff, or debris?
- Are any sections of fins bent flat or crushed? (Kids, dogs, weed trimmers, and hail are the usual culprits.)
- Is there a visible layer of desert dust caked onto the coil? In Las Vegas, this is caliche-rich dust that bonds to the aluminum and hardens. A garden hose alone won't remove it once it's baked on.
Physical Condition:
- Is the unit level on its concrete pad? Settling, erosion, or a cracked pad can tilt the unit, which stresses refrigerant lines and reduces compressor oil distribution.
- Any visible rust, corrosion, or physical damage to the housing?
- Any oil stains on the ground around the unit? Oil stains can indicate a refrigerant leak at a fitting.
Operational Check (system must be running):
- Is the fan spinning smoothly at a consistent speed? A wobble, hesitation, or scraping sound means the fan motor bearings are going.
- Is the fan pulling air upward through the coil? (You should feel a strong updraft from the top of the unit.) If the airflow feels weak, the fan motor or capacitor may be failing.
What You Can Clean Yourself
Turn the system OFF at the thermostat. With a standard garden hose (never a pressure washer), rinse the coil fins from the inside out — stand inside the clearance zone and spray outward through the fins. Work your way around all four sides. Use a gentle, steady stream. The goal is to flush loose dust and debris out of the fins.
Let the unit dry for 30 minutes before turning the system back on.
What Requires a Professional
- Bent or crushed fins: A technician uses a fin comb to straighten them. Don't try this with a screwdriver — you'll make it worse.
- Heavily caked coil: If water alone doesn't clean it, the coil needs a chemical cleaning with professional-grade coil cleaner. This is standard in a spring tune-up.
- Tilted unit: The pad may need to be re-leveled. Running a tilted unit long-term can damage the compressor.
- Fan motor wobble or scraping: This is a bearing failure in progress. A $250–$500 fan motor replacement now prevents the cascade of compressor stress and failure that costs $3,500–$10,000 later.
- Oil stains: Possible refrigerant leak. A technician with electronic leak detection equipment can confirm and repair.
Test #4: The Filter Test
This is the simplest test on the list, and arguably the one with the highest return. A dirty filter is the number-one cause of preventable AC problems — and in Las Vegas, where desert dust loads are three to five times heavier than in most U.S. cities, filters clog faster than the packaging says they should.
How to Do It
Pull your filter out. If you're not sure where it is, check these common locations in Las Vegas homes: the return grille in a hallway ceiling, a slot on the side or bottom of the air handler (usually in the attic, garage, or a mechanical closet), or a wall-mounted return grille.
The light test: Hold the filter up to a light source — a window, a lamp, your phone flashlight. If you can see light passing through the filter media easily, it has life left. If the filter is uniformly gray and blocks most of the light, it's done. If the filter is dark, discolored, or has a visible layer of dust and debris on the intake side, replace it immediately.
The visual check: Look for any damage — tears, gaps in the frame, a filter that doesn't sit flush in the housing. Air bypassing the filter means unfiltered desert dust is hitting your evaporator coil directly, which leads to coil fouling and frozen coils.
Filter Replacement Schedule for Las Vegas
The intervals printed on the filter packaging are designed for average U.S. climates. Las Vegas is not average. Our dust, our runtime hours, and our particulate load all demand more frequent changes.
| Filter Type | Typical Cost | Change Frequency (Las Vegas Summer) | Change Frequency (Las Vegas Winter) |
|---|---|---|---|
| 1" fiberglass (MERV 1–4) | $2–$5 | Every 30 days | Every 60 days |
| 1" pleated (MERV 8) | $8–$15 | Every 30 days | Every 60–90 days |
| 1" pleated (MERV 11–13) | $12–$25 | Every 30–45 days | Every 60–90 days |
| 4" media filter (MERV 11–13) | $30–$50 | Every 90 days | Every 90–120 days |
| 5" media filter (MERV 11–16) | $40–$70 | Every 6 months | Every 6–9 months |
If you have pets, live near a construction zone (which in Las Vegas is most neighborhoods), or have anyone in the household with respiratory issues, lean toward the more frequent end of these ranges.
The Real Cost of a Dirty Filter
A clogged filter doesn't just reduce air quality. It creates a chain reaction:
- Restricted airflow across the evaporator coil
- Coil temperature drops below freezing because there's not enough warm air flowing over it
- Ice forms on the coil, further blocking airflow
- The system runs continuously but can't cool the house
- Liquid refrigerant reaches the compressor (because it's not evaporating in the coil) — a condition called liquid slugging that can destroy compressor valves in minutes
- Emergency repair: $1,500–$4,000 for compressor damage, potentially $8,000–$15,000 for a full system replacement
All from a $12 filter. I've seen this exact sequence play out hundreds of times. The filter is the least expensive, most impactful maintenance item on the entire system.
For the full story on how component failures cascade in the Las Vegas heat, read our component breakdown guide.
Test #5: The Thermostat Accuracy Test
Your thermostat is the brain of the system. If it's reading the wrong temperature, your AC is making decisions based on bad data — running too much, too little, or cycling erratically. A thermostat that's off by just 3°F can increase your energy bill by 10–15% and accelerate wear on every component.
How to Do It
- Get an independent thermometer. A digital indoor thermometer, a cooking thermometer, or even a weather station sensor — anything with a known-accurate reading. Place it on a shelf or table right next to your thermostat, at the same height.
- Wait 15 minutes. Both devices need to equilibrate to the same air temperature.
- Compare the readings. They should be within 1–2°F of each other.
What the Results Mean
| Difference | What It Means | Action |
|---|---|---|
| 0–2°F | Thermostat is accurate. Normal tolerance range. | Pass — no action needed. |
| 3–4°F | Thermostat is drifting. Could be aging sensor, calibration issue, or poor placement (direct sunlight, near a heat source, on an exterior wall). | Try replacing batteries first. If it persists, the thermostat may need recalibration or replacement. |
| 5°F or more | Thermostat is significantly inaccurate. Your system is working off wrong data. | Replace the thermostat. At this level of inaccuracy, the system is either over-cooling (wasting energy and accelerating wear) or under-cooling (leaving you uncomfortable). |
Additional Thermostat Checks
Battery check: If your thermostat uses batteries (most do, even hardwired models — the batteries are backup power), replace them. Low batteries cause erratic behavior: blank screens, lost schedules, random cycling. A $5 battery swap eliminates an entire category of problems.
Programming check: Is the thermostat set for the right season? Some homeowners leave their thermostat in "heat" mode through winter and forget to switch to "cool" in spring. Check that the mode is set to COOL and the fan is on AUTO (not ON — running the fan continuously in Las Vegas wastes energy and can increase humidity issues).
Wi-Fi thermostat check: If you have a smart thermostat (Nest, Ecobee, Honeywell Home, etc.), open the app and verify:
- Is the thermostat connected to Wi-Fi? A lost connection means the thermostat can't receive remote commands or updates.
- Is the cooling schedule correct for the season? Some smart thermostats default to "eco" or "away" modes that may not match your actual schedule.
- Is the learning feature working against you? Some smart thermostats "learn" winter patterns and may be slow to adapt to spring/summer needs. Review the schedule manually.
For a detailed guide on optimizing your smart thermostat specifically for Las Vegas conditions, see our smart thermostat settings guide.
Test #6: The Cycle Test
This test requires patience — about 20–30 minutes of observation — but it reveals problems that no other test catches. You're looking at how your system behaves over multiple cycles: how long it runs, how long it rests, and whether the pattern is normal.
How to Do It
- Set your thermostat to 5°F below the current room temperature so the system has a reason to run.
- Start your phone timer when the system turns on. You'll hear the outdoor unit engage (compressor and fan start) and feel air from the supply vents.
- Time how long the system runs before the thermostat is satisfied and the system shuts off.
- Time the off cycle — how long the system stays off before it starts again.
- Repeat for at least 2–3 full cycles if possible.
Note: In mild spring weather (80–90°F outdoors), the system should cycle on and off. In extreme heat (110°F+), the system may run continuously — that's normal at peak temperatures. This test is most useful in moderate conditions.
What the Results Mean
| Cycle Pattern | What It Means | Action |
|---|---|---|
| Runs 15–20 minutes, off for 10–15 minutes | Normal cycling. System is sized correctly and operating properly for moderate weather. | Pass. |
| Runs less than 10 minutes, then shuts off | Short cycling. Possible causes: oversized system, dirty evaporator coil, low refrigerant, failing capacitor, thermostat problem. | Schedule a diagnostic. Short cycling is one of the most damaging operating conditions for a compressor. |
| Runs 30+ minutes without reaching setpoint (in moderate weather) | System is struggling. Possible causes: low refrigerant, dirty coils, undersized system, duct leaks, excessive heat gain from poor insulation. | Check filter and vents first. If those are fine, schedule professional service. |
| Turns on and off every 2–5 minutes rapidly | Severe short cycling. Possible electrical issue, failed capacitor, thermostat wiring problem, or a safety switch tripping repeatedly. | Turn the system off and call for service. Rapid short cycling can destroy a compressor in days. |
| System starts, runs for 1–2 minutes, trips the breaker | Electrical overload. Possible failed compressor, grounded winding, or severe electrical issue. | Do not keep resetting the breaker. Call for AC repair immediately. |
Why Short Cycling Matters
Short cycling is one of the most destructive things an AC system can do. Every time the compressor starts, it draws a massive surge of electrical current — four to eight times its normal running amperage. That surge stresses the capacitor, the contactor, the compressor windings, and the electrical circuit.
In normal operation, those startups happen five to eight times per hour. In a short-cycling system, they can happen 15–20+ times per hour. The wear is cumulative and accelerates every component toward failure. If your system is short cycling, don't wait. That's a problem that gets worse every day.
For a full explanation of how compressor stress accumulates and what it costs, read our component damage guide.
Test #7: The Sound and Smell Test
Your AC talks to you. It's been telling you things for months — you just might not have been listening. This final test uses the two most underrated diagnostic tools you own: your ears and your nose.
The Sound Check
Turn the system on and walk through your house. Then go outside to the condenser unit. Listen at each location for 2–3 minutes.
Indoor Unit (Air Handler):
| Sound | What It Could Mean | Severity |
|---|---|---|
| Steady, consistent hum | Normal blower motor operation | Normal — pass |
| Whistling or high-pitched whine | Airflow restriction — clogged filter, closed vents, or undersized return | Moderate — check filter and vents |
| Grinding or scraping | Blower motor bearing failure or a loose component hitting the blower wheel | Serious — schedule service this week |
| Rattling | Loose ductwork connection, loose access panel, or debris in the air handler | Low to Moderate — inspect visually, tighten panels |
| Gurgling or bubbling | Condensate drain partially clogged, or refrigerant line issue | Moderate — monitor; if it persists, schedule service |
Outdoor Unit (Condenser):
| Sound | What It Could Mean | Severity |
|---|---|---|
| Steady hum from compressor + fan | Normal operation | Normal — pass |
| Squealing or screeching | Fan motor bearing failure or belt slipping (in older belt-driven units) | Serious — bearings are failing, schedule service before complete failure |
| Clicking repeatedly at startup | Contactor or relay struggling to engage; possible capacitor weakness | Moderate to Serious — have the capacitor and contactor tested |
| Banging or clanking | Loose or broken component inside the compressor housing, or a fan blade hitting something | Serious — turn off the system and call for service |
| Hissing (constant) | Refrigerant leak at a fitting, valve, or coil joint | Urgent — call for service immediately. Refrigerant leaks get worse, not better. |
| Loud buzzing | Electrical issue — failing contactor, loose wiring, or compressor electrical fault | Serious — electrical problems can be safety hazards |
| Humming but not starting | Compressor is trying to start but can't — usually a failed capacitor or a locked rotor | Urgent — turn system off to prevent compressor burnout, call for service |
The Smell Check
With the system running, stand near a supply vent and take a few deep breaths. Then walk to the return vent and do the same. Then go outside to the condenser.
| Smell | What It Could Mean | Severity |
|---|---|---|
| No smell / clean air | Normal operation | Normal — pass |
| Musty, damp, or moldy | Mold or biological growth on the evaporator coil, in the drain pan, or in the ductwork. Common in Las Vegas when monsoon humidity combines with cold coil surfaces. | Moderate — schedule a coil cleaning and drain pan treatment. Consider a UV light system for the coil. |
| Burning or electrical smell | Overheating motor, burning wire insulation, or failing electrical component | Urgent — turn off the system immediately. Do not run it until inspected by a professional. |
| Rotten eggs or sulfur | Not typically AC-related — could indicate a natural gas leak from nearby appliances | Emergency — leave the house immediately, do not flip any switches, and call NV Energy's gas emergency line or 911 from outside. |
| Sweet, chemical, or ether-like | Possible refrigerant leak. Some refrigerants have a faint sweet or chemical odor detectable at the indoor coil or outdoor unit. | Serious — schedule a leak check. Refrigerant leaks are harmful to the system and potentially to air quality. |
| Dusty or stale (first startup only) | Dust accumulated in the ductwork and on the coil during the off-season. Should dissipate within 15–30 minutes. | Normal on first startup — if it persists beyond 30 minutes, the coil or ducts may need cleaning. |
Trust Your Senses
I've had customers describe a sound or smell to me over the phone that led me to an exact diagnosis before I even arrived at the house. "It sounds like a playing card in bicycle spokes" — fan blade hitting a wire. "It smells like crayons" — overheating motor winding. "There's a clicking sound every time it tries to start" — capacitor.
You live with this system. You know what it normally sounds and smells like, even if you've never thought about it consciously. When something changes, that's data. Write it down and report it to your technician. It saves diagnostic time and often saves you money.
Scoring Your System: What the Combined Results Mean
Now that you've run all seven tests, let's put the results together. Each test gives you either a pass, a caution, or a fail. Here's how to read the overall picture.
| Score | What It Means | Recommended Action |
|---|---|---|
| 7 tests pass | Your system is in good shape for a Las Vegas summer. No red flags detected in any category. | Schedule a routine professional tune-up to confirm. A technician can verify refrigerant levels, test capacitors, and check items beyond what this test covers. You're in the "prevention" zone — maintain it. |
| 5–6 tests pass | Your system is functional but has areas of concern. The failures may be minor (thermostat battery, closed vent) or could indicate an early-stage problem. | Address any DIY fixes (filter, vents, thermostat batteries) immediately. Schedule professional maintenance within the next 2–3 weeks — before summer demand overwhelms the schedule. |
| 3–4 tests pass | Your system has multiple issues that will likely worsen under summer heat stress. More than half the tests showing problems means the system is operating outside normal parameters. | Schedule a professional diagnostic this week. Do not wait for summer. Multiple concurrent problems accelerate each other — the cascade effect is real. |
| Fewer than 3 tests pass | Your system is in trouble. Multiple simultaneous failures suggest age-related decline, deferred maintenance, or a combination of issues that will almost certainly result in a mid-summer breakdown. | Get a professional assessment immediately. Be prepared to discuss both repair and replacement options. At this level of failure, replacement may be more cost-effective than repairing multiple components on an aging system. Read our guide on the real cost of running an old AC to understand the math. |
A Note About What This Test Doesn't Cover
This 7-point stress test is a screening tool, not a full diagnostic. There are critical components that only a professional with specialized equipment can evaluate:
- Refrigerant charge — requires pressure gauges and superheat/subcooling calculations
- Capacitor strength — requires a multimeter to measure actual microfarad output
- Electrical connections — requires amp clamp readings and resistance testing
- Compressor health — requires amperage measurement and sometimes compressor analyzer tools
- Duct leakage — requires a duct blaster or smoke test
This test tells you whether something is wrong. A professional tells you what's wrong and how to fix it. Think of this as triage: you're identifying which systems need medical attention, not performing surgery.
What to Do Next: Your Action Plan
You've spent 30 minutes. You have results. Here's exactly what to do with them.
If Everything Passed
Congratulations — your system looks healthy from the outside. Here's your plan:
- Schedule annual maintenance. Even a system that passes all seven tests benefits from the items only a professional can check: refrigerant levels, capacitor strength, electrical connections, and compressor health. A $150–$250 tune-up is the cheapest insurance you'll ever buy.
- Consider a maintenance plan. The Comfort Club handles scheduling automatically, gives you priority service during heat emergencies, and includes discounts on any repairs. In a valley where being at the front of the line on a 115°F day is worth its weight in gold, that priority status alone justifies the cost.
- Mark your calendar. Set a reminder to change your filter every 30 days starting now. Set another reminder to run this stress test again in early June. You want to catch any changes before peak summer.
If You Had 1–2 Failures
Address anything you can fix yourself immediately:
- Replace the filter
- Open closed vents
- Clear debris from the outdoor unit
- Replace thermostat batteries
- Correct thermostat programming
For anything beyond DIY — abnormal sounds, temperature split problems, short cycling, unusual smells — schedule a professional visit within the next two to three weeks. You have time, but not a lot of it.
If You Had 3+ Failures
Call for a professional diagnostic. This week, not next month. Multiple simultaneous issues mean the system is operating under compounding stress, and the Las Vegas summer heat will push every one of those problems past the breaking point.
Be ready for a real conversation about the system's overall condition. If the system is 12–15+ years old and failing multiple tests, the honest math often favors replacement over piecemeal repairs. A new, properly sized system eliminates all seven potential failure points at once — and does it at 30–50% lower energy costs than the aging system it replaces.
Either Way
This stress test just gave you something most homeowners never have: advance warning. You're not going to be the family scrambling for a technician on a 117°F Saturday in July. You know exactly where your system stands, and you have a plan.
That 30 minutes may be the best half-hour investment you make all year.
Frequently Asked Questions
How long should this AC stress test take?
About 30 minutes for all seven tests. The longest individual test is the cycle test (Test #6), which requires 20–30 minutes of observation to see at least two full on-off cycles. The other six tests can each be completed in 2–5 minutes. You can run the cycle test while you're doing other tests — start it first, then work through the others while the timer runs.
Can I do this test if my AC hasn't been turned on since fall?
Yes — and you should. The first startup after months of dormancy is actually the most important time to run these tests. Components that degraded over winter won't reveal themselves until the system runs under load. Set the thermostat to cool, let the system run for 15 minutes to stabilize, then begin the tests. If the system won't start at all (no response from the outdoor unit, tripped breaker, blank thermostat), that's an immediate indication you need professional service before summer arrives.
What's the most important test of the seven?
The temperature split test (Test #1). If I could only run one test on a system I'd never seen before, this is the one I'd choose. A healthy 15–20°F split tells me the core cooling function is working — refrigerant is flowing, the compressor is pumping, the evaporator coil is absorbing heat, and the condenser is rejecting it. An abnormal split tells me something in that chain is broken. Every other test provides supporting detail, but the split is the vital sign.
Should I run this test again during summer?
Yes — I recommend running it once more in early June, just before peak heat season begins. Systems that pass in March can develop issues by June: filters clog from increased runtime, capacitors weaken from thermal stress, and refrigerant levels can drop from slow leaks that open under higher operating pressures. A June check gives you one last chance to catch problems before the July-August peak, when HVAC companies are at their busiest and wait times stretch to three to five days.
What if my AC passes all tests but still seems weak?
If the system passes all seven tests but your house still feels warmer than it should, the problem may be outside the AC system itself. Common causes include: insufficient attic insulation (Las Vegas attics hit 150°F+ and radiate heat into living spaces), air leaks around windows and doors, ductwork that's leaking conditioned air into the attic, or a system that was undersized for the home when it was originally installed. A professional energy audit can identify these issues. It's also possible that the system is properly sized for 105°F but genuinely cannot maintain a 40°F differential on a 118°F day — that's a physics limitation, not a malfunction.
How much does a professional AC inspection cost in Las Vegas?
A standard pre-season tune-up in Las Vegas ranges from $89 to $250, depending on the company and what's included. At The Cooling Company, a maintenance visit includes a comprehensive multi-point inspection: refrigerant charge verification, capacitor testing, electrical connection check, coil cleaning, drain line flush, thermostat calibration, and a full safety inspection. If you're on a Comfort Club maintenance plan, the tune-ups are included in your membership along with priority scheduling and repair discounts. The cost of a single tune-up is less than the emergency service fee you'd pay for a July breakdown call — and it prevents the $1,500–$10,000 repairs that breakdowns cause.
Will this stress test void my warranty?
No. Nothing in this 7-point test involves opening sealed components, handling refrigerant, modifying wiring, or altering any part of the system. You're measuring temperatures, checking airflow, inspecting visible components, and observing system behavior — all from the outside. These are the same observations any homeowner would make during normal use. In fact, most manufacturer warranties encourage regular homeowner monitoring and maintenance. What can void a warranty is failing to perform annual professional maintenance, so if anything, this stress test helps protect your warranty by alerting you to issues that should be addressed during your annual service visit.
The 30-Minute Investment That Prevents the $5,000 Surprise
Every emergency AC failure I've ever responded to in July followed the same pattern. The homeowner assumed the system was fine because it worked last time they used it. They skipped the spring check. They ignored the slightly strange noise, the slightly warm bedroom, the slightly higher electric bill. And then one afternoon, when the thermometer hit 115°F and the system couldn't keep up anymore, everything failed at once.
You just spent 30 minutes making sure that won't be you.
If your results were clean, you earned peace of mind. Schedule a professional tune-up to confirm and maintain that status. If your results showed problems, you just caught them while they're still small, still cheap, and still on your schedule — not the contractor's.
Either way, the next step is the same: pick up the phone.
Call The Cooling Company at (702) 567-0707 or book online. Tell us what your stress test revealed, and we'll take it from there — whether that's a routine tune-up, a targeted repair, or an honest conversation about whether your system is ready for what Summer 2026 is going to throw at it.
Because in Las Vegas, the question is never whether your AC will be tested. The only question is whether you tested it first.