My AC clutch has no voltage to it, fuse is good, swapped clutch relay with known good one, clutch winding ohms out to5.5 ohms, (good I think, at least not shorted or open). I would appreciate an online wiring diagram, and any advice on this sort of problem. Thanks
nrsherman@hotmail.com

 

does the relay energize? using a scanner, see if a/c request signal is coming from the pcm to energize the relay. and while looking at scanner data, see what the computer sees for pressures

 

I will try to check if relay energises, not sue if I can get leads on pins while plugged in--thinkg to ohm across normally opem terminals, see if they are closed. I have b+ and gnd across coil, i swapped relay with different identical relay.

I dont have a scanner thing. What is that, how much, where to buy, where to hook up, how to use, etc

thanks for the reply

 

well, see today's vehicles us computers to control just about evey aspect of it's operation. when you push the snow flake on the dash, you send a signal to a computer to energize a relay to turn on the a/c compressor clutch. however that's not all it is looking at. The computer is also looking at high side and low side pressures and it's looking at aspets of the engine running such as engine temp, throttle position, and engine load.

just because you are not getting power to the a/c compressor clutch doesn't mean it's the relay. it could be you are low on freon, or you have an electrical problem, or a sensor is bad, or etc, etc, etc.

proper diagnosis requires understanding how the system works, what things will interfere with proper system operation. There are certain tools that greatly enhance and improve the accuracy and speed in proper diagnosis and repair.

Say you fell off a ladder and hurt your arm. You'd go to the doctor. You'd want a doctor to diagnose the problem and verify that it is or is not broken. he could squeeze and pull and so on trying to determine if it's broken or he would use a 'scanner' known as an x-ray machine. which method would you think is faster and less painful

Being a novice hobbist trying to save a $ to fix it yourself kinda guy. buying a scanner probably would't be of much value with a one time use.. oh and you just cant get a real scanner at autozone. I'm talking the kind of tool a professional mechanic would own.

So the BEST thing to do is have a professional fix your vehicle. you wouldn't try to set your own broken arm?

oh and if your freon level is low, don't go and buy a can and a hose expecting to put it in yourself. It scares me that people can mess with a/c without any formal training. the danger of the high pressure and the fumes given off can cause severe injury or death.

 

nsherman:
Year/model?
It is true that these systems have many component sensors/signals. And if the 134 freon is low, the clutch will not energize. Also true that this fuse block being next to the battery, as well as the wiring harness and TransCM, causes corrosion and oxidation if the battery leaks any acid or fluids. Thoughtless engineering design.
If the relay is #05269988AA, terminal 30 is always hot, 85 is hot with key on. Get a short wire (1.5 inches or so) to cross 87 and 87c while you push down on relay to get it to make contact in its slots. The wire should be in a U shape. You may have to hold the wire with needle nose to make terminals contact from the side. That will activate the clutch. Don't remember-try with key off first, then if necessary with key on.

 

uh, NEVER jump those terminals. if you don't know which pins to jump, you can fry the PCM.
jump between horizontal line to bottom vertical line \

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