MY COMPRESSOR WONT COME ON BUT THE FAN WILL RUN. UNIT IS NOT SHORTED.CAP. ARE GOOD
If it is an older unit, the compressor may not start (anymore) with the ''correct'' capacitor. (BTW, after checking everything below you should try _new_ caps anyway).
You don't state if it is a window unit or central air. It matters. If it's central air, check the relay inside the air _handler_ (where the fan is). It tells the compressor to turn on and off. The wall thermostat tells the air handler to ''do it's thing'' (so to speak), and the relay inside the handler tells the compressor to turn on. Some older units use what is called a ''sequencer'' (which is just a type of ''timed'' relay switch).
Be careful. There is 220 volts running through it. Make sure _all_ circuit breakers are off. (I mean ''all'' that have anything to do with HVAC in your house, and sometimes there is a breaker outside near the compressor. Make sure it is _off_).
The relays are cheap enough to just go ahead and buy one and replace it. They can go bad after about 5 years depending on usage, humidity levels, etc... It's a good idea to have a spare anyway, so it's not wasteful to replace it as a ''guess''.
If you're certain of _all_ other parts, then you can try a compressor capacitor ''booster.'' They give extra life to compressors that cannot start with just the correct cap anymore. However, be aware that such a situation is highly energy inefficient. Such a compressor would be eating excess energy just to run itself.
Note however, if the ''start'' winding in the compressor is bad, the booster will not work.
Sometimes the ''run'' winding is bad. If so, the compressor will try to start and then fail. (i.e. it won't just sit there dead doing nothing). If that's the case, you _could_ rewire it to actually start _and_ run on only the start winding. However, it will be extremely energy inefficient and will only last a couple of months (at most). You can find info on how to do such things on the web.
It's not particularly dangerous (once it set up that way), but is _is_ the definition of ''jury rig'' and I would be remiss to not caution you against doing it. I only mention it because I know what it's like to not have AC and also not being able to afford an entire replacement system.
Do not attempt _any_ of the above unless you really understand what you are doing. Unfortunately, you _will not_ find a professional willing to do such a thing for you. I even doubt you could find a pro willing to install a start booster.
Ps... Hopefully it is just a bad relay. However, if it is not a relay, and if the cap ''booster'' thing works, you can leave it that way until it fails. It may even last for a few years. Just be aware your energy bills will be about 1/3rd higher.
In closing, the ''start winding'' solution is an extreme ''jury rig'' and it _will_ fail (the winding will burn out) within days to months; there is no way to tell how long. So, if you do go _that_ route, understand that it is _very_ temporary.
May 18, 2015 |
Heating & Cooling