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So, about 4 months ago, at the beginning of summer here in Phoenix, my AC wasn't working properly. After doing a bit of research on the internet, I was able to replace the capacitor and voila...the unit has worked great up until this point.
Now, suddenly this morning...same symptoms as before- air handler is running, blowing air but not cool, fan sounds like it's running (up on my roof, so haven't had time to check it yet...waiting on borrowed ladder to arrive), but the compressor doesn't seem to be turning on (it makes a louder noise than just the fan, so that's why I suspect the compressor not turning on).
I'm just an average home-owner, not an expert, but even though I've heard that capacitors don't last the way they used to, assuming that this is the same issue as before (a blown capacitor), I'm a bit concerned that there may be an underlying issue that's causing the capacitor to blow earlier than normal. I did buy this one on the internet for about $13...super-cheap compared to the retail which is about $45 (at Grainger)...so it makes me wonder if I just got a capacitor that was already a bit weak (I did get the same exact microfarad and voltage, so I don't think that's the problem) ? Or should I be concerned about something else going on that's causing the capacitors to fry earlier than normal?
Without getting too technical (and I am not sure if this is really your problem...) the kind of circuits that HVAC systems typically are divided into two categories. Many residential systes rely on a "permanant split capacitor" they use for the blower motor typically has the capacitor setup as "run capacitor" that is energized whenever the blower is supposed to operating. If it fails it is usually just wear / age of the capacitor / bad luck. Get another one, either from a more reliable company OR substitute two capacitors that properly wired together will have the same capacitance -- assume the original capacitor was rated at 25 mfd, use two 12.5 in parallell and that will give you a little better thermal dissipation.
If the failing capacitor was from the compressor that may be a "start-up capacitor" that is also often used in bigger commericial air handlers where a belted motor can generate more torque. Typically these are rated 100 mfd or more. If the motor is nearing the end of its life (due to bad bearings which get noisy, or windings with increased resistance due to accelerated heat related age...) it is not safe to use an overrated capacitor to give it a bigger kick to start (though I have seen goofy repair people suggest to desperate / cheapskate property owners).
Thanks, Chet. Just to clarify, my capacitor is the type that has the 3 terminals...one for herm, common, and fan.
I just went up there to take a look and the capacitor isn't bulging, but then again I've heard it doesn't always necessarily bulge when going bad. As I suspected, the fan is running fine, but the compressor just isn't turning on. There's no sign of ice on the pipes...it's super hot outside here in Phoenix so can't really tell if the pipes are cool...they seemed kinda cool but not overly so. Since the capacitor is a relatively cheap fix, I think I'll try that first and then see if that fixes the problem.
Note: It's difficult to reach into where the compressor is without having to take off a bunch more bolts (basically taking off the cage/coils that surround it, which would be a pain)...otherwise I would touch it to see confirm it's running or not. But I am able to see it and I didn't see any signs of leakage or whatever, so I suppose that's good.
One of ours died at 7 years of age with no signs of bulging or anything else, and it was a fan+compressor variety but it was easy to diagnose since the fan on the outside unit wouldn't start. A little help from a stick got it going so that was all the diagnosis that was needed. $8.00 and a trip to Ferguson's later, we had ice cold a/c again.
They're easy to replace so why not have a go at it? Just remember to discharge the old one and shut power off to the unit completely first.
One of ours died at 7 years of age with no signs of bulging or anything else, and it was a fan+compressor variety but it was easy to diagnose since the fan on the outside unit wouldn't start. A little help from a stick got it going so that was all the diagnosis that was needed. $8.00 and a trip to Ferguson's later, we had ice cold a/c again.
They're easy to replace so why not have a go at it? Just remember to discharge the old one and shut power off to the unit completely first.
Well, good news! I replaced it this morning and it's working just fine- nice and cold! Yay! Let's hope this one lasts a bit longer than the last one. I bought it at Grainger for $45...not cheap as what I could find on the internet if I had the patience to wait...but, it's just as well. My lesson learned is: since there's no way to test a capacitor long-distance, then it's probably best to buy it locally, and if any doubts, you can even have Grainger test with a voltmeter prior to purchasing to make sure you don't have a dud.
Thanks for the input!
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