Troubleshooting Your Central Air Conditioning System


The worst time to find out your central AC system is on the fritz is during late spring or early summer when the high cost and long wait times for a repairman will have you sweating bullets. So, checking that your AC system is in running order before you need it is highly suggested. This way, you can address any issues you find immediately, saving you both time and money. You can check out some of the companies dealing with heating repair in Dallas, TX

HVAC Direct’s guide will help you quickly and efficiently troubleshoot your AC system for some of the most commonly seen issues by heating and cooling service companies. If you find a problem that you cannot diagnose, seek help from a professional. In the meantime, follow the troubleshooting guide below to see whether a call to an HVAC professional is needed.

PROBLEM:  The air conditioning unit is running but is not blowing cool air.

TRY THIS:              

1. Switch off the power.

2. Change or clean the air filter.

3. Check to see if ice has formed on the power coils? If so, turn on the fan to melt it.

4. Check to see that the condensate drain is clean.

5. Check to see that the outdoor condenser coil is clean.

6. Turn the power back on to the unit and set the thermostat to cooling mode, then set the room temperature as desired.

7. If the unit is still not blowing cool air, contact an HVAC professional.

PROBLEM:  Thermostat indicates the house should be cooled, but the AC unit won’t turn on.


1. Make sure the power to the AC system is turned on by checking the ON/OFF switch located on the air handler or furnace.

2. If you have a battery-powered thermostat, change the batteries. To do this, turn off the power to the AC unit, then take off the thermostat cover and change the batteries. Make sure all wires are secure and replace the thermostat cover. Then switch the power back on to the AC unit.

3. Check to make sure the temperature on the thermostat is set to at least 3 degrees below the room’s temperature, and that the thermostat is set to cool.

4. Check the electrical panels (both main and secondary) for a blown fuse or tripped breaker. If a fuse has blown, replace it. If a breaker has been tripped, reset it by switching off the breaker then switching it back on. Then turn the power on to the AC unit. If the circuit breaker continues to trip, you may have a short in the capacitor, fan motor, or compressor. If this is the case, call a licensed electrician to fix the problem.

5. If the AC unit will still not turn on, contact an HVAC professional.

PROBLEM:  The air conditioning unit is running but is not cooling effectively.


1. Check to see if something is limiting or blocking air flow at any of the key points in the system (air filters, condenser coil, or the return air registers).

2. Check to make sure water is draining from the condensation drain. If no water is detected, this could be a sign of low refrigerant or a system malfunction. Contact an HVAC professional.

3. Check to see if the fan is blowing. If not, consult an HVAC professional.

Troubleshooting an Indoor Air Handler

Dealing with an indoor air handler that has stopped working is fairly straightforward. In fact, there are really only two issues that will cause an AC system’s indoor air handler to freeze up:  low refrigerant levels, which will need to be addressed by a qualified heating and cooling specialist, and limited air flow caused by sluggish fans, dirty air filters and ice buildup on the coils.

PROBLEM:  Your AC system’s indoor air handler has stopped working.


  1. Turn off power to the furnace or air handler unit. If your air handler is a gas furnace, you must also cut the gas supply by closing the gas valve.
  2. Remove the door to the air handler. This will give you access to the air filter. Remove the old filter and clean it, or replace it with a new filter.
  3. Check to see if there is ice on the coils. If you see ice, close the unit and turn on the power to the unit AND the fan. Any ice buildup should melt within 1-2 hours.
  4. If the blower fan is still not working, call your HVAC professional.

Cleaning Your AC System’s Condensate Drain

Air conditioning systems routinely remove moisture from the air using the condenser unit, eliminating the excess water through a plastic drainage pipe located on the side of the system’s indoor air handler. In time, algae may grow, blocking the drain pipe and preventing the AC system from working.

Some systems feature a float switch that automatically turns off the AC if the drained water backs up. To avoid inconvenient shutoffs, make sure to regularly clean the condensate drain by following the steps below:

1. Locate your AC unit’s cleanout port (in line with the drainage pipe).

2. Pour 1 gallon of white table vinegar into the port.

3. Follow up with 2 gallons of hot water to flush out the vinegar.

Doing this just twice a year (once before the heating season and once before the cooling season) will keep the drain clear and your AC system running smoothly.

As you’ve seen, troubleshooting your AC system is an easy and economical way to make sure your home is kept at a consistent, comfortable temperature year ’round.


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