Air Conditioning Capacitors

     After having had a problem with my home air conditioner leaking water repaired the next thing that happened was that it quit blowing cold air! This time it was the capacitor. 
     An air conditioner has many parts and one of the essential components is the capacitor. The capacitor is a small cylindrical container inside the air conditioner and its primary job is to store and supply energy. That is because when the air conditioner starts up, it requires more power than your home electrical system can produce—and that’s where the capacitor comes in. 
     While the air conditioner is running, the capacitor collects and stores energy sort of like a rechargeable battery. That way, when it’s time for that big burst of energy the air conditioner needs, the capacitor can supply it. 
     The air conditioner’s compressor, blower motor and fan motor all rely on the capacitor.  If the capacitor isn’t working, that can lead to all sorts of problems. Sometimes, your air conditioner will be running, but the fan isn’t moving. Other times, the fan may be running, but the air isn’t cold, or the AC doesn’t stay powered on for long. In these cases, it’s likely you have a non-functioning capacitor and it can’t provide the kick start of energy the fan, compressor, or blower needs. 
    Capacitors aren’t prone to malfunctioning, but they do go bad and without a properly working capacitor, your system won’t function properly. The most common signs and symptoms of a bad AC capacitor include: 
# not blowing cold air 
# takes a while to start once you turn it on 
# humming sound coming from your air conditioner 
# shuts off on its own 
# won’t turn on 
# fan not spinning 
# copper tube leading to outside unit is very hot 

     When the air conditioner is not working properly, all sorts of questions come to mind and if you’re the type of person who likes to try to troubleshoot problems on your own, diagnosing the a bad capacitor is fairly easy. 
     It’s not a bad idea to have some idea of what the problem is even if you are going to have a professional make the repairs just to make sure you don’t get scammed for unnecessary repairs. While you could do the repairs yourself, it is infinitely safer for both you and for your air conditioner to contact an HVAC professional! 
     The capacitor for my home air conditioner costs $15 on Amazon, but it would take a few days to get it in the mail and most HVAC contractors won’t sell you parts...they don’t want you making repairs yourself! Besides, I do not like messing with something that may cost thousands of dollars to repair if I mess up something, so I paid $151 to make sure it was done correctly. 
     If the fan on the outside unit isn’t isn’t running a simple test to tell if the capacitor is bad is to take a stick and spin the fan while the air conditioner is running. If the fan starts moving, your capacitor is most likely damaged. 

     If you’re up to removing the access plate and actually looking at the capacitor, if the top of the capacitor is starting to bulge or if there’s leakage, that’s a sure sign that it needs replaced. Be careful monkeying around with the capacitor...remember it stores a charge and needs to be properly discharged!
     Capacitors are subjected to a high strain over its lifetime and having an air conditioner run more than usual increases this strain. Most capacitors are built to last for about twenty years. 
     Generally, the common causes of failure are: 
# Heat exposure - the hotter the area is, the higher the risk for capacitor failure. Overheating it can damage the unit and shorten its lifespan. Keeping your air conditioner shaded and well ventilated can help reduce the risks. 
# Voltage Rating - different AC models have different voltage ratings and using the wrong one (usually because lower voltage ones are cheaper) will shorten their life. 
     A major problem with an AC capacitor failure is that it can lead to damage to other parts that it powers, so once you notice the capacitor is the problem, it’s best to shut down the system and call a repairman.