On Fri, 29 Nov 2019 11:02:59 -0500, Ralph Mowery
wrote:

In article ,
says...

I'd also inspect the relay on the control board that drives the compressor unit,
if possible. Maybe the relay is sticking/failing and sometimes it will not close to activate. He should also measure the voltage at the control board
that goes to the compressor when it's having the problem, see if it has
voltage or not. That would help determine if it's before that point or an
intermittent wiring problem going to the compressor unit. But it doesn't
seem like a wiring thing, since recycling the power restores normal operation.
So far, it sounds most likely a control board problem.

If it looks like that's it, he could buy a new one. If it turns out that it's
not that, very good chance he can sell it on Ebay and get most of his money
back. Very cheap compared to what it would cost to call out an HVAC guy.
the compressor.



I worked for years as an electrician and instrument person at a large
plant, so doing the actual work and measurment ( I have all kinds of
test instruments at home) is no problem. I dealt with computer controled
equipment and some 480 volt 3 phase heaters that pulled about 300 amps.
Just knowing what to look for on this simple controller is my problem.

That thing just will not stay screwed up long enough to find the
problem. It only does it a few times in the winter. Just started a year
or two ago.

I did check the relay that powers the compressor and fan. It did not
have any power going to them. Pushing it in by hand (screwdriver)
starts them.

I may buy a control board off ebay. Seems that I looked into it last
year but did not follow up when I bought a spare capacitor and relay
just so I would have them at hand.

The board would be cheap compaired to calling the man. I learned my
lesson on that a few years back when I was charged about $ 350 just to
have the capacitor replaced.

Since you do seem to have skills, it might be worth making up a test
light with an LED and a 2k or so resistor and hanging it on the white
wire and maybe another one on the green.. Then if that is OK start
moving it closer to the relay that is not getting the pick shot. You
can leave it connected and look at it when it is working, again when
it is failing. In a few failures, you should be able to find the bad
part.