Evans/Tempcon Dash AC Question 1995 Itasca Sunrise P30

[JedtheCamper]

P30 Evans AC question 1995 Winnebago

Problem-no power to Compressor.

Follow my thoughts and process here for a complete picture.

Dash control issue or low pressure switch?

The new compressor is properly charged. The compressor can be "jumped" at its harness-- a hot wire can be ran direct to the battery and will engage and cool properly.

The compressor voltage at the harness running through the firewall is inconsistent on a multi meter. My thoughts are this is why the compressor is not powering when properly connected compared to when it is not jumped.

Turning the key on ACC and switching on air conditioner engages the blower and gives the multi meter reading right below 3 volts.

Cranking, which should show 12 plus volts, throws the harness numbers all over the place and sometimes negative numbers.

The harness is black wire and green, and in this case, black should be hot and not ground...which is weird.

The low pressure switch does not show voltage. It also does not "bing" for continuity.

I replaced the relay and the cooling fan works.

How do I know if this is a low pressure switch issue or a dash controller switch issue?

Everything, including the vacuum system works on the dash controller. The bowden wire did not work, but I have the manual blend door zip tied forward for now.

The defroster, vents, etc all change. I was unsure if the voltage issue lies here with the old school push buttons or with the low pressure switch on the dryer.

Thanks!

Dr. Jed

[JedtheCamper]

Update from today's work.

I did Multimeter tests on the dash switches and the compressor harness. The Dash Switches were fine. I checked the 30amp rectangle block fuse and it was fine. The harness was not showing voltage.

I then checked the low pressure switch and it could not be jumped. The relay that I replaced yesterday was working properly. I found a chart that showed the next in line was the thermostat compressor cut off switch. it is the next square block next to the relay on the right.

I did a continuity test on it and it did not show continuity. I jumped it across wire to wire bypassing the thermostat.

The compressor fired up, but it squealed like a pig. I am currently working from here.

I am thinking maybe the low pressure switch or high pressure switch could be bad. It possibly could be over or under charged.

The belts are new and tight. the compressor is new.