AC Conundrum

[Ck2hans]

Had Featherlite rebuild my HVAC basement unit about 4 years ago (new compressors, new fan motors, new capacitors, new control board, new thermostat), everything ran well afterwards. About a year ago I was at a site that had very low voltage and it fried my fan motor and the control board. I replaced the fan motor and control board then installed the Micro-Air soft starts on the units. The system has worked flawlessly for just short of a year, but now the 1st stage compressor is dropping out after a couple of days of use. I can restart the system and it will work fine for a couple of hours then 1st stage drops out again. It can be immediately restarted but then only runs for a 1/2 hour or less.
Compressor is running at 7-8 amps (well within normal range), shot relays on circuit board with thermal gun, everything is within normal range, unit cools fine when running. Start and run capacitors tested within range but weak so I replaced all of them (fans & compressors). System went back to running normal for 3 days (cycling off & on), but now 1st stage is starting to drop out again yet still restarts immediately without any issues.
It’s got me baffled, everything operates normally within parameters but then 1st stage suddenly drops out, yet will restart and run without issues immediately. Doesn’t make sense, something should be showing out of normal operating range before failure.
What am I missing?
Chuck

[Fratto]

Chuck, does your unit have two compressors or a single two stage compressor?

Could it be a control issue? Control board / sensor sees something that it does not like, takes the compressor off line. Then when you restart it resets the controls?

For grins have you put gauges on it. Unlikey you will be reading them when it goes off line, but still it may be another clue

[RichardE]

Chuck,
can you be more specific on dropping out? The whole unit shuts down? The compressor shuts down? You will have to follow the voltage to diagnose this. If the comp has voltage coming out of the board but comp is not running I would check thermal overload. If voltage is not present check to see if board is getting signal to close relay.

[Ck2hans]

Mark:
Unit has two compressors. I do not have gauges, plan on taking to a shop for that part of diagnosis.

Richard:
Clarification of systems operation - System starts; outside and inside fan run on low and #1 compressor cuts in, after 3 minutes inside fan and outside fan switch to high and #2 compressor comes online. When temp is within 2 degs of set temp inside and outside fan go back to low and #2 compressor stops (#1 remains running). If set temp is achieved #1 compressor, inside & outside fans stop, and system remains in standby for next cycle once temp rises. If temp rises 3 deg above set point when system is on #1 compressor, low inside/outside fan system will then bring #2 comp back online and fans will return to high.

What is happening is I notice the interior temp rising when system is in high fan operation (meaning both compressors should be running). I check the amp gauge and can see the #1 compressor is not running, BUT #2 is still running and both fans are still on high speed. With the blue tooth connection on the Micro-Air soft stops I can also see zero amps on #1 compressor.

I understand your recommendations and will follow through with that testing, my current obstacle is Featherlite put the HVAC basement unit in the middle of the bay and the generator box on the passenger's side with the generator radiator and squirrel cage fan on the driver's side and in front of the HVAC basement unit, so to access the control board and wires I have to drain the antifreeze from the generator and remove the radiator and squirrel cage fan. Been there and done that before, problem is we are in the middle of a trip right now and that's not really an option as necessary as it is. Good old Murphy's Law gets in the way again.

Chuck