It always happens on the worst day. It is July, 95 degrees outside, the AC is running, and the air from the vents is barely cool. By noon the house is 84 and climbing.
There is a reason it happens on the hottest days. A system can limp along at 80 degrees outside with a small problem. Push it into the mid-90s with Georgia humidity and that small problem becomes the difference between cool and not.
Check these four things first
- Thermostat. Set to Cool, fan on Auto, a few degrees below room temperature, fresh batteries.
- Filter. If you cannot see light through it, replace it.
- Outdoor unit. Is the fan spinning? Is the coil caked with pollen or grass?
- Breakers. Check both the outdoor unit and the indoor unit breakers, and the disconnect next to the outdoor unit.
If you see ice on the copper lines, turn the system off and set the fan to On for a few hours to thaw it before we arrive. Running a frozen system can damage the compressor.
The eight most common causes
1. Failed capacitor
The capacitor helps the motors start, and heat is hard on it. Signs: the outdoor fan does not spin, the unit hums, or it works on and off. A quick repair, usually on the truck.
2. Dirty outdoor coil
Spring pollen bakes onto the coil and the unit cannot get rid of heat. Signs: the outdoor unit runs constantly and the air inside is only cool. A coil cleaning is part of every AC tune-up.
3. Low refrigerant
Usually a slow leak. Signs: the house will not drop below 78 to 80, the air is cool rather than cold, ice on the lines. The leak should be found and repaired, not just topped off.
4. Frozen indoor coil
Caused by low airflow or low refrigerant. Signs: no cold air at the vents and frost on the larger copper line.
5. Clogged filter
A filter that looks a little dusty can block a lot of airflow, freezing the coil or starving the house of air.
6. Failed contactor
The switch that powers the outdoor unit. Pitted contacts cause the unit to run intermittently or not at all.
7. Blower motor
The indoor fan that moves air through the ducts. Signs: the outdoor unit runs but little or no air comes out of the vents.
8. Compressor
The heart of the system and the most expensive repair. On an older AC, we will show you the repair price next to a replacement estimate.
Typical prices
| Repair | Typical total price |
|---|---|
| Capacitor | $150 – $300 |
| Contactor | $150 – $350 |
| Refrigerant leak repair and recharge | $200 – $1,500 |
| Blower motor | $700 – $2,500 |
| Evaporator coil or compressor | $2,000 – $3,500 |
Small repairs are the $89 diagnostic plus the repair price. Large repairs are quoted as one price that already includes the diagnostic. You approve the price before we start.
How to avoid the July emergency
- A spring AC tune-up in March to May catches weak capacitors, dirty coils and low charge before peak heat. It is $135 for one system.
- Change the filter every 30 to 90 days.
- Keep 2 to 3 feet clear around the outdoor unit and rinse pollen off the coil in spring.
- Plan members ($229 a year, $189 the first year) get priority scheduling during heat waves and no diagnostic fee.