OK..I'm working on a 95 RR 4.0Se and I am trying to troubleshoot my AC but have no idea where to find any kind of schematics on it. First I checked all fuses and relays.... All good. Then I check the Freon level...... good. I jumpered the compressor and checked that with my guages. Now I am down to the High/Low pressure switches which I believe I just found hidden behind the bumper and the thermal switch located on the evaporator.

So here are my questions... Does anybody have wiring and pinout on the High/Low pressure switches so that I can test them and can you tell me where the connector would be located to the thermal switch on the evaporator so that I don't disassemble the whole dash trying to find it. Also an ohm range related to temperature on the thermal switch would be helpful.

Thanx in advance
Steve

 

Ok..... I found the Evaporator Temp Sensor (Dash is pretty much in the back seat, LOL) and it measures 3.75 K ohms at 88 deg F. I'm not sure what it should read but it seems to adjust smoothly when a temperature change is present.

If that is fine then I bet there is some sort of seperate control unit that reads this sensor that could have a problem. Or it could still be the High/Low pressure switch on the lines. I'm at a loss and in the mean time I am sweating my @$$ off!

I have been all over the internet for the last 2 days and can't find crap for wiring. I purchased a manual and for $150 you would think that schematics would be included. HA!

If there is anything else that I may be missing please offer any suggestions.
Thanx again
Steve

 

LOL...YOUR NOT GOING TO BELIEVE IT!! I traced and traced and in the back of my mind I knew that there was nothing wrong with any one particular component in this AC system. An hour or so ago I realized that a new relay was put in my fuse box that is not listed in the book or on the Fuse Box cover (relay 10) Come to find out this was later put in as a retrofit to fix another problem that certain P38's were having with the compressor not engaging,(I think it is a low impedance problem or something like that) This relay ohmed out to the compressor so that really got me excited. I noticed that the signal wire to the relay was not working so to me, that was showing that the PCM was not giving me a signal. All paramaters were met going into it so what could it be? The PCM? LOL nope ...... a damn mouse or something had gotten up under the fuse box and chewed the wire. The tape was chewed up on the wrap and the shielding was chewed all up around the wire and the wire was frayed in two. It was the only wire damaged in the bundle coming from the cab, thank god, so after 2 days of wire chasing I finally found it and got a good laugh at the same time.

Thanx guys
Steve

 

Nice, I have found a lot of strange things wrong with my 94 RRC LWB, but I have you to run into a rodent issue. Thanks for the run down; it should come in handy for the rest of us when trouble shooting our A/C.