Advanced air conditioning troubleshooting for the homeowner.

 In this previous article, we talked about basic air conditioning troubleshooting. Read it first before jumping into this one.  Advanced air conditioning troubleshooting takes more knowledge, more tools and a keen eye to safety!

So far we have worked our way to the outside unit and are looking for issues. The next step is to check capacitors. Think of capacitors as electronic batteries and keep in mind they have a potential charge that can hurt! There are plenty of guides on the internet for checking capacitors. Due to space limitations we won’t cover those here. Capacitor failures are a common issue.

After you have checked the capacitor, return power to the unit. Check that the contactor for the unit closes. This will be an audible click as the solenoid pulls the heavy contacts closed. If the unit does not start, look for a reset button as some units have a high pressure cutout reset switch. If need be, use your voltmeter to check for voltage to the unit and to the contactor. The contactor probably has 24v and the unit either 120 or more commonly 240V. Be careful! Problems here could be the contactor, wiring from the electrical panel or breakers, thermostat and low voltage wiring to the contactor.

When the compressor starts, the cooling fan should be running. If not, check the cooling fan motor as this is another common failure. If the fans is not working the compressor will cut out due to high pressure. If you have a fan running but no compressor, there could be several issues including low refrigerant, overheated compressor or even a bad compressor.

Is there ice or frost anywhere? Ice or frost is a symptom of refrigerant issues. If your unit has ice, shut it down and wait several hours for all the ice to melt. Restart the unit and check to see if the ice is forming again. If so call us!

So now we have a running compressor, with the cooling fan and the blower in the house all working but the air does not seem to be cool. We can check the operating efficiency by simply measuring the temperature difference between the cooled air and the air entering the return duct. Make sure the unit has been on for at least 15 minutes. Look for about 20 degrees for a high efficiency unit and more like 15 degrees for an older unit.

Still not right? Make sure the air flow is good through the blower, filters and ducts.  Air flow can be improved with better blowers, or increasing blower speed, and even enlarging ductwork.

Still not right? Save yourself the headaches and call us. We will let you watch as we demonstrate advanced air conditioning troubleshooting. After all we have had 40 years of practice!