Well, here it is March 3 which places us in meteorological SPRING. (And, for those in the U.S., don’t forget that Day-light Savings Time starts THIS WEEKEND ). I know that those of us up north and out east are still dealing with the last of winter but soon, we will be starting air conditioners and changing heat pumps over to cooling. So now is the time to start thinking about what needs to be done to get those units cooling.
Over the years, I have seen all sorts of “check-lists” for doing air conditioning and heat pump maintenance. Some are simple 10 point checks. Some get into more detail. Some go the whole distance and make sure everything is checked. What I will be presenting in the next few posts is what I always felt should be part of PROPER MAINTENANCE on any air conditioner or heat pump. This applies to both split systems as well as packaged units. Feel free to separate out the air conditioning stuff from the heat pump stuff if you don’t deal with heat pumps. Feel free to use any of these suggestions to create your own check list. Remember that air conditioners and heat pumps are SYSTEMS. There are “indoor and outdoor” components.
For those of you who do deal with heat pumps, remember that these unit are operating year round and need a little more attention.
Keep in mind that SAFETY SHOULD ALWAYS BE FIRST! A lot of these checks will be performed on LIVE equipment and it is imperative that you practice proper safety measures and have the proper PPD (personal protection devices) and properly functioning meters.
Whether dealing with just an air conditioner or a heat pump, one of the first things I always check is the disconnect switch. When you pull the handle to the OFF position, does it really shut off the power to the unit? Over time, disconnect switches can wear out and may not “kill the power to the unit”. Always verify, with a meter, that the power is off before putting your hands into any electrical component or control box. While you are checking the disconnect, it is a good time to recorded the Line Voltage. At the same time, check and record the Control Voltage. Now, with the power off, check and tighten all the electrical connections. Through normal operation, electrical connections can become loose or corroded causing potential failure of the connection or a components. This little step alone can save motors, contactors, capacitors, compressors, etc. so don’t omit this step.
With the power still OFF, now is a good time to inspect components. Check out any contactor in the unit. Look at the “contacts’ to see if they are pitting or show signs of “arcing”. Is there “black” showing on the contacts? Do the same for any relay or contactor in the control panel. This is also a good time to check capacitors. Inspect and take readings on the “herm” capacitor, “fan” capacitor (keep in mind that some units have dual capacitors with both the herm and fan in one can) and check the micro-farads and make sure the readings are within the tolerance (+/- %) listed on the capacitor. Weak or out of range capacitors will cause the compressor or fan to eventually fail or the unit to not always start. Today, with more units using Expansion Valves for better efficiency, and as a result have either full start components (start capacitor and potential relay) or have “super boost” start assist kits on them. These should also be checked at this point.
It is very important to check the compressor at this point. Open the cover on the electrical connections of the compressor. Make sure there are no loose or corroded connections at these terminals. Replace questionable connections as necessary. Remove the wires and ohm out the windings and check them to ground to make sure the compressor does not have any internal electrical problems.
It is also good to see if the unit is equipped with a crankcase heater. If it is, ohm it out to make sure it is good. This is especially important on heat pumps since they are operating in the winter.
Now, all of these checks were performed with the power OFF. In my next post, we’ll start the unit and do some further electrical check and look at the refrigerant side of the system. We’ll also do some “visual” inspections.
Stay tuned — more to come!