AC Troubleshooting: “Why Is My Central Air Conditioner Not Cooling?”

Posted 04-07-15 in Air Conditioning

Is your home’s central air conditioner not cooling your house? Perhaps it’s blowing luke warm or hot air.

There are a variety of things that could cause your AC to not cool your home properly.

But for your convenience, we’ll categorize the problems into ones YOU can solve and ones only a professional air conditioning repair technician can solve.

AC problems that you can solve

Problem 1: Thermostat set to “ON” instead of “AUTO”

Does your AC blow out cool air sometimes and lukewarm air other times? Then the fan setting may be set to “ON” which just runs the fan 24/7—even when the air isn’t being cooled.

Solution: Set the thermostat to AUTO.

Problem 2: Dirty air filter

A dirty air filter reduces airflow into your AC, causing several problems:

  • AC struggles to circulate enough cool air to get your home to the desired temperature (e.g. your thermostat is set on 74 your temperature never drops below 80).
  • Evaporator coil (the part that cools the air) literally freezes, turning into a block of ice that blocks air, meaning that your home gets very little cooled air at all.

Solution: Check the air filter and change it if it looks like the filter on the right

Dirty HVAC air filter

Problem 3: Dirty outside unit

Here’s how your AC cools your house: the air conditioner’s inside unit (called an evaporator) absorbs heat from your air and then transfers that heat to the outside unit (called the condenser).

But the condenser can’t dissipate heat if it’s dirty or crowded with debris. This causes your air conditioner to struggle to cool your home.

AC condenser needs cleaned

This condenser could use some cleaning.

Solution: Spray the outside unit with a garden hose on a gentle setting. DON’T blast it on a high setting or you’ll bend the fins that allow airflow to cool the condenser off.

Also, remove any weeds growing around the AC unit. Give it some breathing room!

Problems an AC professional needs to solve

Here are just a few problems that a professional air conditioning contractor may need to fix:

Problem 1: A faulty or broken condenser fan motor

If the fan motor is bad, then the outdoor unit’s fan can’t help dissipate heat, meaning that the AC can’t cool your house.

Problem 2: Low refrigerant charge/refrigerant leak

Refrigerant is the liquid that absorbs the heat from your air. When you don’t have enough, your AC can’t absorb enough heat to cool the air. A low refrigerant level means one thing: you have a refrigerant leak.

Signs you have a refrigerant leak include:

  1. Ice buildup on the refrigerant line and the outside unit
  2. Bubbling or hissing noise
  3. AC can’t cool home on especially hot days, but cools fine on cool days and at night

If you see these signs, turn off your AC and call a professional ASAP. Running the AC in this state can cause slugging in the compressor and damage it beyond repair.

Speaking of compressors...

Problem 3: A bad compressor

The compressor is the heart of the AC system, circulating refrigerant like blood between the inside and outside unit. If it’s damaged, then the AC can’t cool your air.

If there’s an issue with the compressor, then it may need replacing. Unfortunately the compressor is uber expensive. So unless you have a warranty on it, you’ll probably need to replace an entire outside unit.

Live in the Atlanta, GA area? Contact us for help

Did you try solving the problem yourself? Is your AC not cooling your house after checking these possible issues?

If you’re in our service area, then contact us for an air conditioner repair—scheduling online saves you 10%. Whether your air conditioner is a Carrier, Trane, Rheem, Goodman, Amana, Bryant, Lennox, York, or any other brand, we can help!

Save 10% when you book service online

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