It's 98°F outside. Your AC is running but the house is 85°F and climbing. Before you call us (and definitely before you panic-buy a new unit), here are the five most common reasons an AC isn't cooling — and which ones you can fix yourself in 5 minutes.
I'd estimate half the "AC emergency" calls we get are one of these five issues, and a few are simple homeowner fixes. Let's walk through them.
1. Dirty or Clogged Air Filter
This is the #1 cause and the easiest to fix. A clogged filter restricts airflow over your evaporator coil. The coil gets too cold, freezes solid, and now no air can move through — so no cool air reaches your rooms.
How to check
Pull the filter out. If it's gray-brown instead of white, or you can't see light through it, replace it. Then go look at the indoor coil (usually accessed through a small panel near your furnace). If you see ice on the copper lines or the coil itself, you've got a frozen coil.
The fix
- Replace the filter
- Turn the thermostat to "OFF" — let it thaw for 3-4 hours (don't run it)
- Turn the FAN to "ON" (not auto) to speed thawing
- Once fully thawed, switch back to COOL and see if it works
If it freezes again — call us. Could be low refrigerant or a bad blower.
2. Outdoor Unit Is Covered in Dirt or Grass
The big metal box outside (the condenser) needs to dump heat into the outdoor air. If it's clogged with grass clippings, cottonwood fluff, leaves, or dog hair, it can't dump heat — so your AC works overtime and your house stays warm.
How to check
Walk outside. Look at the condenser. The metal fins should look clean. If you see a thick mat of grass or fluff on any side, that's your problem.
The fix
- Turn off the breaker to the outdoor unit (or the disconnect box next to it)
- Gently spray water from the inside out using a regular garden hose (no pressure washer — fins bend easy)
- Let it dry fully before turning back on
While you're there — make sure nothing is within 2 feet of the unit. Bushes, fences, lattice, weed barriers — all kill airflow.
3. Thermostat Settings or Bad Batteries
Sounds dumb, but it happens. Someone changed the schedule. Batteries died. Mode got switched from COOL to FAN. The thermostat is offline from your wifi network.
How to check
- Is it actually set to COOL? Not FAN or AUTO without a setpoint?
- Is the setpoint actually lower than current room temp?
- Battery thermostat: pull batteries, check if the display works at all
- Smart thermostat: is it on wifi? Did an app schedule override the temp?
4. Tripped Breaker or Blown Fuse
ACs draw a lot of power. Especially on the first hot day of the year when the system has been sitting idle for 6 months, weak breakers will trip.
How to check
- Go to your electrical panel
- Find the breaker labeled AC, A/C, or Condenser
- Is it tripped (middle position) or off?
- If tripped: flip fully OFF, then back ON
Also check the disconnect box mounted next to the outdoor unit. It has a pull-out fuse cassette. If a fuse is blown, that'll kill the outdoor unit while the inside still runs (blowing warm air everywhere).
If a breaker trips a second time after resetting it — STOP. You have a real electrical problem. Call us. Repeatedly resetting tripped breakers can start fires or damage the equipment.
5. Low Refrigerant (You Have a Leak)
This is the one homeowners can't fix. Refrigerant doesn't "get used up" — it's a sealed loop. If you're low on refrigerant, you have a leak somewhere. Common signs:
- AC runs constantly but the house barely cools
- Ice forming on the copper line near the indoor unit (the larger of the two lines)
- Hissing or bubbling sound from the indoor unit
- Higher electric bills
- System cools fine for an hour then stops
This is where we come in. We pressure-test the system, find the leak, repair it, evacuate, and recharge. Just "topping off" refrigerant without fixing the leak is illegal (R-410A is a regulated refrigerant) and pointless — it'll leak right back out.
Run this checklist before calling anyone:
1. Check filter — replace if dirty
2. Check outdoor unit — clean if matted
3. Check thermostat — confirm COOL, low setpoint, batteries good
4. Check breakers and fuse disconnect
5. Listen for hissing, look for ice
If any of those reveal the problem, you might save yourself a service call.
When to Call a Pro
Call us if:
- You've checked everything above and it still won't cool
- The system is making strange noises (banging, screeching, gurgling)
- You see ice on the lines or coil
- Burning smell from any part of the system
- Water leaking from the indoor unit
- Breaker trips repeatedly
- The unit is 12+ years old and acting up — may be time to talk replacement
We answer 24/7 in summer. Don't suffer through a 95° night.