If your air conditioner isn’t cooling properly, making strange noises, leaking water, or triggering your home’s circuit breaker, chances are it’s suffering from a common ac problem that HVAC pros see all the time. In this blog, we’ll cover the top 10 most frequent air conditioner problems, what causes them, and how they can be addressed.
I compiled this list based on insights from a technician who kept records of the service calls he responded to over a summer season. Out of 242 total AC repair orders, he tracked the issues encountered and ranked them by frequency. These stats provide a fascinating glimpse into the problematic patterns homeowners deal with year after year. Read on to see if your AC woes match up with some of the most typical cooling system failures.
#1 – Bad Capacitor
By far, the most common AC repair was a bad capacitor, accounting for 52 out of 242 service calls. Capacitors help start the compressor and fan motor. They can bulge or leak dielectric grease when failing. Causes include normal wear and tear, very dirty coils, and power surges. Confirming a bad capacitor requires testing it with a meter. Replacements are inexpensive and straightforward. Just match specifications and wire exactly the same.
#2 – Low Refrigerant Charge
The second most frequent AC issue, with 28 cases, was low refrigerant or Freon level. Since ACs are sealed systems, any loss of refrigerant indicates a leak. Common leak points are coils, brazed joints, and refrigerant lines. Topping off refrigerant can provide temporary cooling but leaks need repair. Unfortunately, coils often require full replacement. Watch for frozen evaporator coils – a sign of low refrigerant.
#3 – Plugged Condensate Drain Line
In the #3 spot with 14 calls was a plugged AC condensate drain line. This causes water to overflow the drain pan and leak from the furnace. Debris from the coil fins or algae in the drain line are common clogs. Using a wet/dry vac, air, or wire to clear obstructions usually fixes this issue. Just be ready for some water spillage!
#4 – Failed Control Board
An air conditioner’s control board failed 13 times, landing it the #4 most common repair. Symptoms of a failed control board include no power to the outdoor condenser, simultaneous AC and furnace operation, or an non-functioning blower fan. This results in a frozen evaporator coil as coolant can’t circulate. Control boards must be replaced by a pro and properly calibrated.
#5 – Burnt Out Condenser Fan Motor
A seized or stuck condenser fan motor occurred in 12 calls. The fan blades won’t spin freely, causing hot air discharge and eventual tripping of electrical overload protection. Fan motors can sometimes be oiled back to health, but replacing the motor and capacitor entirely is the permanent solution.
#6 (Tie) – Bad Blower Motor
Problems with the blower motor accounted for 11 service visits. Blower issues prevent air from circulating through the evaporator coil, resulting in freezing. Bad bearings, stuck rotors or electrical shorts are typical causes. If just the capacitor is faulty, replacing that may get it going again temporarily.
#6 (Tie) – Compressor Shorted to Ground
Also occurring 11 times was an AC compressor internally shorted to ground. This causes immediate circuit breaker tripping upon startup. Proper diagnosis involves isolating the compressor and checking for resistance between windings and ground. Replacement is required if shorted.
#7 – Very Dirty Air Filter
Air filters prevent debris from accumulating on sensitive internal components. Eight homes had filters so clogged that airflow was obstructed, leading to frozen coils, limited cooling, and strain on the blower motor. Check and change filters monthly during AC season. Use proper sizing and pleated media styles.
#8 – Tripped Circuit Breaker
A tripped air conditioner circuit breaker happened 7 times. While debris or unbalanced power can cause nuisance breaker trips, repeated or immediate tripping flags a short circuit needing repair. Isolate the compressor and condenser fan motor to determine which has failed insulation causing the short.
#9 (Tie) – Common Condenser Problems
Five more issues tied for the #9 most frequent AC problem:
- Complete refrigerant loss indicates a severe leak requiring full recharge and extensive leak testing.
- Condenser coils blocked by dirt, cottonwood, leaves and debris require thorough spray washing to allow adequate airflow.
- Failed contactors won’t send power to the compressor. Burnt contact points or pitted surfaces indicate replacement is needed.
- Leaking evaporator coil drain pans cause water damage but require full coil replacement to fix. Condensate leaks out despite proper draining.
- Mouse nests full of shredded insulation indicate chewed wiring. All damaged wiring must be replaced. Clean droppings thoroughly.
#10 (Tie) – Compressor Problems
Our final two tied AC issues, with 5 appearances each:
- High locked rotor amp readings mean the compressor is drawing too much current. Hard start kits can sometimes get stuck compressors running again.
- Inefficient compressors don’t move refrigerant properly due to bad valves. Low pressures on gauges confirm worn parts. Replacement is required.
Don’t Sweat AC Issues – Now You Know What to Watch For!
Diagnosing and preventing common AC problems comes with experience. But armed with this background on what technician’s encounter daily in homes, you’ll have a leg up identifying issues before they worsen.
Don’t hesitate to ask an expert for advice if your AC starts exhibiting any of these common failure symptoms. Catching problems early saves money and hassle down the road. Stay cool out there!
Let me know in the comments if your AC ever suffered from one of these typical issues. And please share if this overview helps you troubleshoot future problems!
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