2nd Gen Non-Engine/Transmission no ground @ac relay

[L BECKER]

Whats wrong when there's no ground on air conditioner relay coil on 1995 dodge. Is it computer? If it is is it possible to bypass the computer?

 

[BDaugherty]

It sounds funny, but check the horn fuse. That's what powers the dash controls.

 

[BLNRAY]

ground is most likely controled by the pcm,if you have power to the relay might want to check system pressure,low charge pressure will keep the comp from coming on as will high press.

 

[L BECKER]

Are the low & high pressure switches on the ground circuit. I seem to have continuity on both switches.

 

[DavidC]

This is for a 99, maybe some help

Dave

 

[DavidC]

The diagram that led to the previous

Dave

 

[L BECKER]

Horn fuse seems to be good.

 

[L BECKER]

It looks like the low & high pressure switches have continuity,wondering if I can bypass the pcm or if the only place to get one is the dodge dealer. Wondering how much $ a pcm is.

 

[L BECKER]

Diagram makes sense. Not no easy way to bypass pcm. Wondering if the dodge dealer is the only place to get a pcm or if their is aftermarket how many $.

 

[DavidC]

You really need a service manual for your truck unless you plan on not having it in the near future. What I sent you was for a 99. Are the wire colors and PCM pins the same ?, I do not know. I would not start jumping anything until I knew how the circuit operates. Could be as simple as a bad plug, broken wire etc. if you have an ohmmeter and the correct diagrams you can trace those out to verify. As far as I know replacing a PCM is big money and has to be programmed for your particular vehicle. techauthority.com or genosgarage.com probably has your manual either in paper, CD, or download. I have the paper and CD for mine. The cd is nice as you can print the pages you want and if they get messed up you simply print another. You may have a PCM problem or it is not seeing the inputs it needs to do the output for the relay.

Dave

 

[DavidC]

Does not look like techauthority has it but genos still shows it
http://www.genosgarage.com/Dodge-Factory-Service-Manuals/products/241/

Dave

 

[HHhuntitall]

Is the tach and alternator working? If you lose one of those, you'll lose the A/C clutch, too. Also, there is a common ground in the starter solenoid wire. If you unplug the relay for the starter, you lose the A/C clutch. I used to see guys who tried to wire in push buttons or anti-theft switches and lost their A/C with the switch activated.



The PCM has to have the signal from the tach that there is engine rpm for it to engage the A/C clutch.

 

[DavidC]

I dug up the rest of the diagrams for at least a 99

Dave

 

[L BECKER]

Thanks for the drawings. You tell me I don't know how it works. I changed the fan resistor & as of now the compressor clutch is working?????

 

[L BECKER]

Tach & alternator works fine.

 

[HHhuntitall]

Hmm, I'd wager the A/C clutch is powered through the fan, like the 1st gen trucks, and not the PCM. That may make sense, seeing as how it's a '95 instead of a late '96. There were many changes when they went to the OBDII system in the PCM. Just another note to add to the TDR and our own mental records. On a '97 I worked on this winter, I could hear the A/C clutch cycle, but had no power to the fan switch... . Finally found the relay under the dash had been unplugged, and everything was fixed once it was plugged back in... . I wouldn't have thought your '95 was any different, but appears to be. .

 

[Bob4x4]

the 95 ac clutch relay is supplied B+ from the horn relay ckt. The coil b+feed is through fuse #9 (10amp) The ground side of the relay coil is triggered by the pcm. (c13) 22db/or

 

[Bob4x4]

The pcm ac request signal comes from the hvac switch through the hi and low pressure switches (c90) to the pcm

 

[Bob4x4]

Hmm, I'd wager the A/C clutch is powered through the fan, like the 1st gen trucks, and not the PCM. That may make sense, seeing as how it's a '95 instead of a late '96. There were many changes when they went to the OBDII system in the PCM. Just another note to add to the TDR and our own mental records. On a '97 I worked on this winter, I could hear the A/C clutch cycle, but had no power to the fan switch... . Finally found the relay under the dash had been unplugged, and everything was fixed once it was plugged back in... . I wouldn't have thought your '95 was any different, but appears to be. .

lol I'll take that bet

 

[Bob4x4]

Hmm, I'd wager the A/C clutch is powered through the fan, like the 1st gen trucks, and not the PCM. That may make sense, seeing as how it's a '95 instead of a late '96. There were many changes when they went to the OBDII system in the PCM. Just another note to add to the TDR and our own mental records. On a '97 I worked on this winter, I could hear the A/C clutch cycle, but had no power to the fan switch... . Finally found the relay under the dash had been unplugged, and everything was fixed once it was plugged back in... . I wouldn't have thought your '95 was any different, but appears to be. .

lol I'll take that bet