Spokane summers can surprise you with week-long stretches in the 90s. When your AC starts blowing warm air during a heat wave, it’s more than uncomfortable—it can be a sign of a problem that gets worse if ignored. Here are the five most common causes.
1. Dirty Air Filter
A clogged filter restricts airflow over the evaporator coil, which can cause the coil to freeze—ironically resulting in warm air from your vents. Check your filter first. During Spokane’s wildfire smoke season, filters clog faster than usual. If the filter looks gray and matted, replace it and give the system an hour to recover.
2. Thermostat Set Incorrectly
It sounds obvious, but it happens: the thermostat gets bumped to HEAT, or the fan is set to ON instead of AUTO. With the fan in ON mode, the blower runs constantly—even when the compressor isn’t cooling—so you’ll feel room-temperature air between cooling cycles. Set the mode to COOL and the fan to AUTO.
3. Low Refrigerant
Refrigerant doesn’t get “used up”—low levels mean there’s a leak somewhere. Signs include warm air, ice on the refrigerant lines, hissing sounds near the outdoor unit, and the system running constantly without cooling. Refrigerant handling requires EPA certification, so this one always calls for a professional.
4. Dirty Condenser Coils
Your outdoor unit’s condenser coils release heat from your home. When they’re caked with cottonwood fluff, grass clippings, or dirt—all common in Spokane—the system can’t shed heat efficiently. You can gently rinse the coils with a garden hose (power off first), but never use a pressure washer, which can bend the delicate fins.
5. Tripped Breaker or Blown Fuse
Your AC has both an indoor and outdoor electrical disconnect. If the outdoor unit isn’t running at all (no fan hum), check the breaker panel and the disconnect box near the condenser. A tripped breaker can indicate an electrical issue, so if it trips again after resetting, call for service rather than forcing it.
Frequently Asked Questions
Why does my AC run but not cool the house?
If the system runs continuously but the temperature doesn’t drop, you may have low refrigerant, a failing compressor, or ductwork issues. Check the filter and thermostat first, then call a technician if those look fine.
How often should I service my AC in Spokane?
Once a year in spring, before cooling season. Our short but intense summers mean your AC sits idle for mon
