Home & GardenInteriorsVentilationTroubleshooting Your Central Air Troubleshooting Your Central Air Split-system central air conditioners, used with forced air furnaces, take hot air from the house and blow it through an evaporator coil located in the top of the furnace to cool the air. The cooled air circulates throughout the house via the heat ducts then returns to the furnace as warm air to be cooled again. Central air conditioners can work for years without problems if properly maintained and serviced annually. If they aren’t working properly, call a trained technician. But before you phone, see if the problem is caused by something else. The unit stops working If you have your system inspected and cleaned annually, it should run without any trouble. However, if it stops working completely and you aren’t sure why, troubleshoot before calling a pro: Check the circuit breaker or fuse box to find out whether the unit has power. Check the fuses in the disconnect box located outside, near the condenser, to make sure there’s power.

Replace or clean the furnace filter. If the condenser coils are coated with dust or debris, use a garden hose to wash them off. If the air conditioner still won’t work, make the call. A technician may have to recharge the refrigerant. The unit won’t quit running If the air conditioner runs constantly, here’s what to do: Turn up the thermostat. If you set the thermostat a few degrees higher, you will save energy and a lot of money when it comes time to pay your electric bill. And your significant other won’t have to complain about wearing a sweater indoors. Take the cover off the condenser and find out whether anything is blocking the air flow. Vacuum the interior of the condenser, and then flush it with a garden hose. If the fan blades are bent or dirty, straighten them out and/or clean them. While the cover is off, oil the motor on older air conditioners. (Newer units are sealed and cannot be oiled.) Take off the plastic covers — there should be two — and put a couple drops of lightweight oil, such as 3-in-1, into each.

Check the furnace filter and blower to see whether they’re blocked. Use a vacuum cleaner to clean dust and dirt on or around the blower. Replace the filter if necessary. The unit freezes up If the high pressure lines from the condenser to the furnace or the evaporator coil in the top of the furnace are iced up, then shut the system down: Either turn off the breaker in the panel or pull the disconnect switch outside at the condenser.Your system is probably low on Freon and needs to be recharged. Water pools under the evaporator When there’s water under the evaporator at the base of your furnace, the drain is probably clogged. You can clear it, but it’s probably easier just to replace the whole thing. If you want to try clearing it, however, here’s what to do. Take off the trap, and if it’s PVC (plastic) you can cut the pipe to remove it. Pour a vinegar-water or bleach-water solution (1 to 10 parts) into the drain. That will help remove debris and algae.

If you have flexible tubes, take them off and clean them by pouring the solution through them. You can also run a wire through the tube to scrape the walls. Do it gently so you don’t poke a hole. Reassemble the tubes and trap.Condensing Unit Frozen Wont Turn Off - What you can expect to learn from Condensing Unit Frozen Wont Turn Off article: this article is an answer from a question taken from our email by a visitor to High Performance HVAC. window ac unit best buyWe often use the questions we get in the email as a guide to write articles. new ac window unitThe topic is a condensing unit that will not turn off and it is freezing up. ac unit is 25 years oldFrom my experience in the field and using my HVAC knowledge I offer the readers a list that could cause this problem. 

We hope it helps you. What’s the possible problem with a frozen air conditioner condenser that won’t turn off except with the breaker?Condensing Unit Frozen Wont Turn OffThe Answer for frozen air conditioner condensing unit that won’t turn offRelated Link: Here is a similar but different problem with a frozen air conditioner.There are 3 possible problems with this unit and will probably need the attention of an HVAC Technician for repair. Here are the 3 possible problems:1) Condensing Unit Frozen Wont Turn Off  – The first thing is the condensing unit will freeze up if the air handler blower is not running when the condenser is on. The condenser is pumping liquid refrigerant to the air handler evaporator coil where air is needed to blow across the coil so the cold refrigerant can absorb heat. If the refrigerant is not absorbing heat because the blower is not blowing air across the evaporator coil then the condenser will freeze. This often happens when everything is working fine but the filter is plugged up, duct work is collapsed, or the blower motor fails.

In this case, the blower is working fine but the condenser will not turn off so the thermostat is cycling the air handler blower on and off but the condenser is not turning off. It is possible you have a defective thermostat but I would check two other things first.I would check the compressor contactor to see if it was stuck in the closed position. Under normal operation when the thermostat calls for cooling (heating in a heat pump) a 24-volt signal is sent to the compressor contactor inside the air conditioner condenser unit. This energizes and closes the contacts of the compressor contactor which is basically a switch controlled by the thermostat. This allows high voltage to pass to the compressor and the condenser fan motor. When the switch or compressor contactor closes and opens a slight arcing of electricity happens and over time this causes pitting of the contacts. It can also cause the contacts to stick so the even when the thermostat disengages the compressor contactor or stops sending the 24-volt signal the unit will continue to run because the contacts are stuck and will not release.

The compressor contactor needs to be replaced and this should be done by a qualified HVAC technician. When the compressor contactor sticks like this the only way the condenser will turn off is if you turn the main power off to the condenser as you have been doing when you need air conditioning. 2) Condensing Unit Frozen Wont Turn Off  – The other possibility for your problem is the thermostat wires are bad somewhere. These would be the thermostat wires that go to the air conditioner condensing unit. Old thermostat or damaged thermostat wire will cause the condenser to run and not shut off. Old thermostat wire loses the insulation and the copper which the insulation protects touches and feeds continuous voltage to the compressor contactor. Same thing with a damaged thermostat wire. Leave the condenser on and turn the power off to the air handler to test this. This will kill the 24-volts which feeds the compressor contactor. If the condenser turns off then you have either a bad thermostat or the wire problem described here.

New thermostat wire needs to be pulled from the thermostat to the condenser to fix this problem and I recommend you get a professional to do this job. Has some work been done lately around the house where someone was driving nails into the wall? If so then a nail could have pierced the wire and this is causing your problem. 3) The next thing it could be is a bad thermostat. If you have checked all the other things and nothing happens carefully disconnect the yellow wire from the Y terminal on the thermostat. If the unit shuts off then you have a defective thermostat and needs to be replaced.Related Link: Delve deeper into controls circuits and how control circuits work. Related Link: Here is a result of a similar problem with a frozen air conditioner that was not repaired and caused severe water damage.Condensing Unit Frozen Wont Turn Off - ConclusionWhichever problem you have it is probably best to call an HVAC contractor that specializes in service to repair this air conditioner problem.