Air Conditioner Repair Checklist
1. AC Won’t Turn On
There can be several explanations why your AC unit won’t run: a triggered circuit breaker, inaccurate thermostat settings, a turned off switch or an overflowing condensate drain pan.

Overloaded Circuit Breaker
Your AC won’t turn on when you have an overloaded breaker.
To see if one has blown, find your house’s main electrical panel. You can find this gray fixture on the wall in the basement, garage or closet.
- Make sure your hands and feet aren’t wet before you check the panel or breakers.
- Find the breaker marked “AC” and make sure it’s in the “on” location. If it’s overloaded, the lever will be in the "off" position.
- Steadily transfer the breaker back to the “on” spot. If it instantly triggers again, don’t touch it and call us at 573-635-3547. A fuse that keeps tripping might indicate your house has an electrical problem.
Wrong Thermostat Settings
If your thermostat isn’t telling your system to start, it won’t turn on.
The key part is making sure it’s on “cool” and not “heat.” Otherwise your AC might not start running. You could also receive warm air coming from vents since the heater is going instead.
If you have a regular thermostat:
- Replace the batteries if the screen is empty. If the screen is displaying garbled numbers, replace the thermostat.
- Make sure the right program is showing. If you can’t update it, reverse it by dropping the temperature and pressing the “hold” button. This will make your AC start if programming is wrong.
- Try setting the thermostat 5 degrees below the space’s temperature. Your AC won’t start if the thermostat is identical to the room’s temperature.
Once your thermostat is set accurately, you should start getting cool air promptly.
If you’re using a smart thermostat, including ones produced by Nest, Ecobee, Lux, Honeywell or Bosch, check the manufacturer’s website for troubleshooting. If it still won’t work, contact us at 573-635-3547 for support.
Shut-Off Switch
Your cooling equipment typically has a power-cutting lever around its outside unit. This switch is generally in a metal box mounted on your home. If your unit has recently been repaired, the switch may have unintentionally been turned off.
Clogged Condensate Drain Pan 
Condensate drain pans catch the additional liquid your system takes out of the air. This pan can be situated either below or within your furnace or air handler.
When there’s an obstruction or clogged drain, water can accumulate and prompt a safety control to turn off your system.
If your pan includes a PVC pipe or drain, you can drain the surplus liquid with a special pan-cleaning tablet. You can buy these tablets at a home improvement or hardware store.
If your pan has a pump, look for the float switch. If the lever is “up” and there’s moisture in the pan, you might have to install a new pump. Call us at 573-635-3547 for help.
2. AC Blows Warm Air
If your equipment is on but not cooling, its airflow may be obstructed. Or it could not have adequate refrigerant.

Blocked Airflow
Your system’s airflow can be reduced by a clogged air filter or filthy condenser.
How to Replace Your Air Filter
A filthy filter can create countless troubles, such as:
- Limited airflow
- Frozen refrigerant lines or evaporator coil
- Inconsistent cooling
- Larger utility costs
- Causing your system to stop working faster
We recommend installing new flat filters monthly, and pleated filters every three months.
If you aren’t sure when you last replaced your filter, shut off your system completely and take out the filter. You can find the filter in your furnace or air pump’s blower compartment. It may also be found in a connected filter case or wall-mounted return air grille.
Angle the filter up to the sunshine. If you can’t see any light, you need to buy a new filter.
4 Steps to Cleaning Your Cooling System
Weeds, vegetation and bushes can block your condensing system. This could limit its airflow, impact its energy efficiency and affect your comfort. Here’s a way you can get your equipment working smoothly again.
- Switch off electricity fully at the breaker or outside lever.
- Get rid of plant rubbish around the air conditioner. Once you’ve removed bigger refuse within a two-foot space, you can use a fine-bristled brush or vacuum to slowly clean the equipment’s fins. Crooked fins can also hurt capability.
- Use a hose nozzle to gingerly clean the fins from inside the equipment. Make sure to avoid getting liquid on the fan motor.
- Restore the power.
Leaking Refrigerant
When air conditioning units don’t have enough refrigerant, they’ll have difficulty removing heat and humidity from your home.
Here are a few signs that your system is losing refrigerant:
- It takes an extended amount of time to refresh your residence and you’re continually turning down the thermostat.
- Air coming through the registers isn’t as chilly as it should be.
- You’re noticing whistling or gurgling noises when the air conditioning works.
- Your evaporator coil is iced over due to having difficulty absorbing heat.
Suspect your equipment is leaking refrigerant? You need a licensed heating and cooling service specialist to fix the leak and restore the right measurement of refrigerant in your system. Reach us at 573-635-3547 for support.
3. AC Not Blowing Enough Air
When it appears like you’re not receiving ample amounts of cold air, there’s probably an obstruction or detachment inside your AC equipment.
- The beginning step is checking your air filter. Get a new one if it’s dusty.
- Make sure the registers are open across your house.
- If you’re still not receiving adequate chilly air, you should have your ducts inspected by a professional like Stieferman Heating Company Inc. Your ductwork might need to be repaired or relinked in limited space locations like your attic, basement or crawl space.