I have an older Rheem central AC unit at my house, I'm afraid I can't find the model number anywhere. The compressor quit running but the fan still runs. I've played around with the unit, the contactor is working and if I bypass the capacitor for the compressor I can get it to run for about a second or two. Could it be the capacitor or is the compressor itself defective. Any help would be greatly appreciated

It may be the capacitor, you can either take it and have it tested or replace it, they are not to expensive, Good luck, Mike

You say you can get the compressor to run for a second or two. Are you sure it is running or is it just making a buzzing noise? If it is buzzing it might be the capacitor like acetc said but I would bet that it is the compressor itself.

If you have an ohmmeter, you can do a rough check of the capacitor. Short across the terminals and disconnect one. Connect the ohm meter. It should show a high reading at first and then quickly climb off scale. Any other reading means it is bad. If it seems to be good, may as well call a technician to evaluate the compressor, although it could be something such as a high pressure switch.

I have an older Rheem central AC unit at my house, I'm afraid I can't find the model number anywhere. The compressor quit running but the fan still runs. I've played around with the unit, the contactor is working and if I bypass the capacitor for the compressor I can get it to run for about a second or two. Could it be the capacitor or is the compressor itself defective. Any help would be greatly appreciated
Hey everybody thanks for all the info. I'm sorry but I haven't had a chance to investigate the issue any further. I took the capacitor out of the unit but haven't had a chance to get it check out or buy a new one. As soon as I get a chance I'll look at it and post the results. This is an awesome site and I appreciate everyone's assistance

Update it is the compressor, I was wondering if there was a way to find out if I can just replace the compressor or does the entire outside unit need to be replaced.

You have to get a service man with a freon certificate to do the compressor work. And when it comes time to replace a compressor there are a lot of things you need to think about. How old is the unit? How efficient is the unit? If you put in a new compressor be sure and buy the extended four year warranty.
A service man it going to jump the price up for changing the compressor because it is a harder job than changing the complete unit our side therefore he will try to up his profit a bit to make up for the lost time of changing the compressor.
Then if you do change the compressor you still have an old AC unit, a fan motor that might go out, contactor/s that might give trouble, hundreds of solder joints that have been vibrated for years that could be ready to start leaking, plus the efficiency has to be very low if it is a very old unit. Let me know if I can help you anyway.

Do you have any idea how expensive it will be to replace it. Do you need to change both the outside and inside units?

Inquiring minds want to know, Thanks for your input

You don't have to change both units. It is mostly a question of can you afford it. Of course it would be best if you could afford to replace both at the same time. But if you have to you can change the outdoor unit and then sometimes later change the inside coil and the furnace.

The price depends on the size of your unit and the area you live in. Plus what S.E.E.R you but, this has to do with the efficiency. The higher the number the higher the efficiency.

Also some energy companies give rebates you need to check into this.