HeyBub wrote:
Ken wrote:
HeyBub wrote:
We survived Ike in extremely good shape compared to others in the
vicinity. The only significant problem is the AC unit: the
compressor won't come on. My AC guy swapped out the start & run
capacitors, bypassed the
relay, and checked all the obvious stuff. No compressor action. He
theorizes that power-line chatter at the storm's outset could have
so confused the aged system that it committed suicide trying to keep
up. His best guess is a seized compressor piston on this 17-year old,
3-ton, Trane and he's checking with his buddies for a used
condensing unit. Observations and suggestions would be welcome.

Thanks.


Does the fan for the condenser unit start?

No.

Your condenser unit may be different, but many have the fan motor wired
in parallel to the compressor. In other words, when power is applied to
the compressor it is also applied to the fan motor. Having them both
fail at the same time is very unlikely. Check to see if they are wired
in parallel and make sure you are getting power applied to these units
when the contactor is latched.

Did he measure the voltage at the leads going to the compressor?

Yes

And it was 220/240 volts? See above comment.

Why did he bypass the relay
(contactor)? Was it not latching up?

Even if the relay latches, the points could be burned, preventing contact.

True, but one would only do this if there was not proper power applied
to the compressor and fan motor.




I know these are fundamental
checks, but you would be surprised at how some pros diagnose a unit.

Well, the first thing he did was test the start capacitor and pronounced it
"marginal." So he replaced it. No joy. That's when he went through the "try
this, test that" mode.