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

 

What is the problem? Is the compressor turning on at all? My temp probe had what seemed like ok resistance but when the a/c blew cold the compressor would shut off after a few secs. Turned out the resitance changed as it should but then all of the sudden dropped out completely. I can't tell you where that stuff is but a manual off ebay should.

 

Compressor does not come on at all, no fans on the condensor either. I have found everything but am still needing wiring diagrams to find out weather all the paramaters are being met before the PCM and if so.... which wire is the output FROM the PCM triggering the compressor clutch relay? Just being able to test the high/low pressure swithes, which there happens to be 2 of on this truck one being a trinary switch, would help alot. What a pain in the *** without schematics. My code reader doesn't check ac on/off so I'm pretty much running blind. I think I'll just put a toggle switch in her cab for her with a big red wire running to the compressor, LOL!

 

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