Things To Check Before Calling For A/C Repair
There are several things you can check before calling for service. Checking a few things first may save you an unnecessary service fee.
Air Filter A dirty air filter can reduce the airflow to your system and cause a freeze up in the summer. It can cause your unit to overheat in the winter. Dirty air filters are one of the top 10 things that we get called out for. It seems such a waste to have to pay a technician to come out to tell you your filter is dirty! In the summertime, if you can hear your system running but no air is coming out of the vents (or very little air), then this may be the cause of your trouble. Try replacing the filter (click here for recommendations on what type of filter to use) and then turning the system switch on the thermostat to "off" and setting the fan switch to "on" for a minimum of 2 hours. This will defrost the system in the event that it was frozen up from a restricted air filter. After the 2 hours switch the thermostat back to cool and set the fan switch to auto and see what happens.
In the winter time, if you have a heat pump or a furnace, and the fan runs but only unheated room-temperature air comes out, then try replacing the air filter and resetting the circuit breaker. Some heat pumps and furnaces have a pressure safety or temperature safety that actuates when the airflow is reduced by a dirty filter and it can be reset by turning the power off briefly (for at least 1 full minute). Try it and see what happens. It may save the cost of a service visit.
Thermostat Batteries Many digital thermostats require batteries (usually two AAA or AA). Weak batteries can cause the thermostat to function erratically. Thermostat issues are one of the top 10 things we get called out for. If you are unsure of the age of your batteries, or if you just want to try this as test to see if it cures the problem, replace the batteries and see what happens. Some digital thermostats also have a reset button. You can research your thermostat model on the internet to see if yours has a reset, and if it does you can also try resetting the thermostat and see what happens.
Thermostat Programming Programmable thermostats are complicated and confusing sometimes. You can have the system selector switch set to the cool or heat position and even though you think it should be running, oftentimes the programming overrides the temperature you believe it is set to and the unit will not run. If you suspect this is the issue, try pressing the "temperature hold" button and selecting the temperature you desire. This will override the programming. If your unit runs in the hold mode then your programming needs to be changed.
Circuit Breaker A tripped circuit breaker will keep your unit from running of course. If you have the thermostat set for cooling or heating and you don't hear anything running, the cause may be a tripped breaker. Split systems usually have 2 circuit breakers, and it may be possible to hear the fan blowing air inside the house but the outside unit is not running. Sometimes a circuit breaker will trip and there is a cause (requiring a repair), but many times there is no known cause. A power surge can cause the breaker to trip. You can try resetting the breakers and see what happens. If it trips again right away then don't try to reset it again. Call a qualified technician to check it out, there is likely a serious issue that needs repair.
Fuses Some HVAC systems use fuses and some do not. For those people who are mechanically inclined (and you feel safe and responsible doing this), if your A/C system has fuses, you can go to the hardware store and buy replacements and try that to see if it cures the problem. Be sure to get the correct fuses if you decide to replace them. They must be the correct ampacity and of the correct type (dual element, time delay, type FRS or FRN). Beware, there are fuses at the hardware store that are for "general purpose" use and they cost only about $5 for a two pack, but these are the wrong ones (click here for a picture of the wrong fuses)! Do not attempt to use general purpose fuses, they must be time delay dual element fuses for an air conditioner or heat pump unit. The general purpose fuses will fail if you attempt to use them. Please note before replacing your fuses, if you can hear your blower running or you can see the propeller fan running on the outdoor unit, it is unlikely that you have a blown fuse.
Defrost Unit A unit can freeze up in the summer from a number of different causes. Sometimes just setting the temperature down to low can cause this to occur. A restricted air filter can cause a freeze up. If too many air vents are closed off it can reduce the airflow and cause a freeze up. Oftentimes a combination of these 3 things can cause freeze ups. If you can hear the A/C system running but little or no air is blowing out, it likely may be frozen up. Try replacing the filter (click here for recommendations on what type of filter to use), opening all the supply air vents and then turning the system switch on the thermostat to "off" and setting the fan switch to "on" for a minimum of 2 hours. This will defrost the system in the event that it was frozen up. After the 2 hours switch the thermostat back to cool and set the fan switch to auto and see what happens. To avoid freeze ups, don't ever set the thermostat below 70℉ in the summer.
Vacuum Condensate Water leaks are sometimes caused by a dirty or restricted air filter (which causes a high negative pressure on the return side of the blower, which in turn causes air to be drawn through the condensate drain preventing the water from freely passing through the line). It is also sometimes caused by a plugged or partially plugged condensate trap. Sometimes it is a combination of the two things that causes condensation water leaks. Try replacing the filter (click here for recommendations on what type of filter to use) and then try attaching a wet-n-dry vacuum (VERY important, do not use a regular vacuum, as water will be coming out of the line!) to the end of the condensate drain line to try to clean out the line and trap. If you are mechanically inclined (and you feel safe and responsible doing it) you can find the vent tee on the condensate line and put a piece of tape over it before using the wet-n-dry vacuum. This will much more effectively clear the line of its contents. After the vacuum is completed be sure to remove the tape. This simple procedure may stop your condensate leak!