Your AC is running but the house still feels warm. Here’s a Spokane HVAC tech’s checklist for what to try before you book a service call, and how to tell when it’s time to call in a pro.
It’s a July afternoon, the thermometer on the shop wall says 94 degrees, and your thermostat is set to 72 — but the air coming out of the vents feels barely cooler than the room. Sound familiar? Every June through August, this is the single most common call our dispatchers take: “my AC is running, but it’s not cooling.”
The good news is that a warm-air complaint doesn’t always mean a broken compressor or a five-figure replacement. Sometimes it’s a $12 filter. Sometimes it’s a breaker. Sometimes it genuinely is a refrigerant leak or a failing capacitor that needs a licensed tech. Below is the same troubleshooting order our techs walk through on a first visit, so you can rule out the easy stuff yourself before scheduling a service call.
Start Here: Is It the Thermostat?
Before you touch anything mechanical, confirm the thermostat itself isn’t the problem.
- Make sure it’s set to “Cool,” not “Auto” or “Heat” — an easy thing to miss if someone bumped it.
- Confirm the set temperature is actually below the current room temperature.
- If it’s a battery-powered or smart thermostat, check for a low-battery icon or a blank screen.
- On smart thermostats (Ecobee, Nest, Honeywell), check the app for scheduling conflicts — a “vacation” or “eco” mode can quietly override your setting.
If the thermostat display is dead entirely, that’s often an electrical issue downstream, which leads to the next check.
1. Check the Air Filter First
A clogged filter is, by a wide margin, the number one reason a Spokane air conditioner blows warm-ish air in the summer. When airflow across the indoor evaporator coil is restricted, the coil can actually freeze over — and a frozen coil can’t absorb heat from your home’s air, so what comes out of the vents feels lukewarm or even warm.
Pull the filter and hold it up to a light. If you can’t see light through it, replace it. In homes with pets or during Spokane’s wildfire smoke season, filters can clog in as little as 30 days instead of the usual 60–90.
2. Look for Ice on the Indoor Coil or Refrigerant Lines
Open the indoor unit’s access panel or look at the copper lines running to the outdoor condenser. Frost or solid ice is a sign of restricted airflow (dirty filter, blocked vents, failing blower motor) or low refrigerant. Either way, don’t run the system — turn it to “Off,” not just “Fan,” and let it thaw completely (this can take several hours) before doing anything else. Running a frozen system continuously can damage the compressor.
3. Check the Outdoor Condenser Unit
Walk outside to the condenser — the metal box with the fan on top. It needs airflow to reject heat, so:
- Clear grass clippings, cottonwood fluff, leaves, and debris from around the unit (keep at least 18–24 inches clear on all sides).
- Confirm the fan is actually spinning. If it’s silent and not turning, that’s a component failure (capacitor or fan motor) — not a DIY fix.
- Look at the coil fins for a heavy coating of dirt or pollen; a garden hose (never a pressure washer) rinsed gently from the inside out can help, but a buildup like this usually calls for a proper coil cleaning.
4. Check Your Breaker Panel
Central air conditioners typically run on a dedicated 208/240-volt breaker. If the outdoor unit is completely dead — no hum, no fan — check your electrical panel for a tripped breaker. Reset it once. If it trips again immediately, stop and call a technician; a breaker that won’t hold is telling you something is drawing too much current, and repeatedly resetting it risks damaging the compressor.
5. Check the Condensate Drain and Safety Switch
Many residential and nearly all commercial systems have a float switch on the condensate drain pan that shuts the whole system down if the drain line clogs (algae growth is common by mid-summer). If your system was cooling fine and then stopped entirely, a clogged condensate line tripping the safety switch is a strong possibility. This is a simple fix for a technician and worth mentioning when you call.
6. Check Supply Vents and Return Air
Walk the house and make sure furniture, rugs, or curtains aren’t blocking supply registers or the return air grille. A partially blocked return can starve the whole system of airflow, which — again — can lead to coil icing and weak output at every vent.
7. Listen for Unusual Sounds
A healthy outdoor unit hums steadily. Pay attention to:
- Clicking that repeats without the fan starting — often a failing capacitor or contactor.
- Loud buzzing — can indicate an electrical or motor issue.
- Hissing or bubbling — can point to a refrigerant leak, which is not a DIY repair and, depending on the refrigerant type, is regulated under EPA Section 608 rules that require a certified technician to handle.
8. Check the Age of the System
If your central air unit is pushing 15–18 years old, reduced cooling capacity can simply be the compressor wearing out. R-22 refrigerant systems (common in units installed before 2010) are also increasingly expensive to service since R-22 was phased out of production. If you’re facing a major repair on an older system, it’s worth getting a straight comparison of repair cost versus installing a new, higher-efficiency system — our techs will give you both numbers in writing so you can decide, not guess.
9. Consider Whether the System Was Ever Sized Right
Occasionally we get called to a home where the AC has “never really cooled the upstairs” — and the issue isn’t a malfunction at all, it’s a system that was undersized (or a ductwork layout that was never balanced) for the home’s square footage and window exposure. If your cooling complaint is really a comfort complaint that’s existed since day one, that’s a conversation about airflow and duct design, not just refrigerant.
A Quick Reference: DIY vs. Call a Pro
When It’s Time to Call
If you’ve worked through this list and the house is still warm, stop troubleshooting and get a real diagnosis. A tech carries gauges, a thermal camera, and amp meters that will find the actual root cause in minutes rather than hours of guesswork — and a proper written estimate means you know the cost before anything gets touched.
Advanced Mechanical Systems has been diagnosing Spokane-area cooling problems since 1984, and same-day service is available for most calls during business hours across Spokane, Spokane Valley, Liberty Lake, Cheney, and North Idaho including Coeur d’Alene, Post Falls, and Hayden. If you’re dealing with no cooling at all during a heat spell, that qualifies as an emergency call — we typically respond within two hours.
Ready to get it fixed? Schedule a free consultation or call us directly at (509) 534-0547.