Compressor stopped temporarily

Here are my symptoms, which are close to, but not exactly the same as other posts I have read...

During a thunderstorm last night, I noticed that a buzzing noise was coming from my coolant line in the basement. Sounded like someone had replaced my A/C compressor with my noisy little pancake air compressor. An hour later, the noise was gone, but so was the cooling. Duct trunk was room temperature, coolant return line wasn't even slightly warm. Outside, the fan was blowing full speed, compressor was silent.

I thought maybe a momentary loss of power earlier had stunned the compressor into an auto-protect mode, so I tried flipping off the breaker, pausing, and flipping it back on. No change. Next I thought that the delay switch may have gone bad, as the last one did back in 2002. About 90 minutes later, however, I noticed that the compressor had come back on. The duct trunk was cold, the line was warm (but not hot), and I could hear both the compressor running and the coolant flowing in the lines.

This morning, the weather has cooled off considerably, so the thermostat is not calling for cooling. I turned down the temp just to test, and the compressor came on as normal.

Is it possible that the delay board is going, but not yet gone? That wouldn't explain the buzzing, though, would it? Could the power dip have damaged the compressor?

Thanks in advance for any suggestions!

 

I would go ahead and replace the capacitor.

 

Ok...makes sense. You think the compressor was buzzing because it was unable to fully start on its own? Today, everything is working just fine, btw.

I looked for specs but the outer casing of the capacitor is completely rusted. The serial plate doesn't say, either. Is there a reliable place to find such info online? It's a Bryant 597CN036-B.

Thanks again.

 

Check the schematic sometimes the capitance may be on there, if not you have a tough search ahead. Remove the old capacitor and gently wipe the rust off maybe you can see it if you are careful. I have had the factory reps give me bad info at times on the correct capacitor, especially on older units the information seems to evaporate or something.

 

The capacitor on my 1993 Copeland Compliant was not labeled with anything to identify it. I did a web search of the compressor part number and was able to locate the capacitor requirements. I just kept clicking sites until the info popped up. Good luck.

 

Ok, I'm halfway there. In the photos below, you can see that I have two single capacitors hooked together (it's a little hard to see but that one black wire loops around from the small capacitor to the large one). How lucky am I that the capacitors never slipped and shorted each other out??

I have identified the small capacitor as an Aerovox SuperMet 370V 7.5uF. I found it online for $8. The other is much harder to read. I have posted a photo of that, too. I haven't yet found anything online that I would say is an exact match. It looks like it says 35UF, but the SuperMet of the same physical size (3.75" tall x 1.75" base) is listed as 45uF.

Finally, there are very few references to my Copeland Compliant Scroll model number online. One is actually in another DIY forum about my exact problem, but the thread ended with no resolution.

Any guesses on what the larger of the two capacitors is?

 

In your first photo, right next to the 18 is marked 35u. u=mfd

 

While cleaning out my inbox, I came across DIY's reply notifications for this thread. I just want to report that it's been a year and everything is still working fine. I did not replace the capacitors, and I have not heard any buzzing sounds since the original incident. So, if anyone else is having a similar problem, I'd suggest:

1) Turn off the breaker for a few minutes to let the system calm & cool down.

2) Be patient after turning the breaker back on because the unit might be in a time- or temperature-based self-protect mode.

3) If things still don't return to normal, I guess you really do have a problem.