OK Back at it. Here are the results.

AC Switch Test with AC on and the thermostat plugged in again -
I get the Beep at presure switch!

DC Volt reading a second time on P/S connector plug and have:
Red/White = 11.59
Blue / Yel = 3.87

Light Test from Battery Ground AC on & Thermo plugged in

Grounded test light at bat and on red/white = Aux fans go on ?
Grounded test light at bat and on yel/black = Nothing

I will look for test trace back directions in manual for trouble shooting as recommended.

 

If you did the voltage test correctly, there is a ~8V drop across the pressure switch. There should be negligible drop. Suggest rechecking, as replacing pressure switch will require refrigerant removal.

Another check is to check resistance across pressure switch contacts. If there is a measureable resistance, the switch is bad.

When you grounded the red/wht through the test light you provided ground path and enabled the cooling fans to run.

Possible problem w/ the blk/yel (to thermostat?). It should have read 12V if the keyswitch was On. Either fuse 8 open or wiring fault. Again, check your results.

good luck

 

Is the switch good? the reading on the presurre switch was a -4.36 when meter set on ohms.

 

Switch resistance should be near zero, < 1 ohm. Note, when you zero an analog meter or check a digital meter w/ shorted terminals, note the resistance. This should be subtracted from digital readings.

good luck