alright......i thought i had everything together and installed on my EATC, but now for some reason my A/C wont work.......

before i installed the EATC, it worked like a dream....i just had it serviced and all new seals put in it......

alright, i have 12v power at BOTH electrical connections at the compressor.....i just put on a brand new clutch, pulley, and coil.......when i jump a wire from the battery to the clutch coil, it engages the clutch, but when the plug is pluged in, the coil wont engage.........the compressor is free and turns........i have tried to by-pass the safety switch and it still wont engage......

if i read the EATC How-To instructions properly, the Y/BLK wire from the EATC HU is susposed to go to the R/O wire in the trucks wiring harness to engage the A/C relay......i was told that it would show 0v when the A/C was selected to be on, and it would read 13v when the A/C was off.......it is reading 13v both times............

anyone know what i could try besides a new compressor....i think i just went and spent $85 on a new clutch and didn't need it.....

any help would be great....

 

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thanks bob......i will try that tomorrow when i get off work.......hopefully that is all it is....

 

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whenever i stick both of my voltmeter leads into the plug that goes to the clutch i see 12v.......i didn't mean to say i had 12v on both sides.......sorry for the confusion.......

i also have 12v on the electrical plug on the back of the compressor........

 

The EATC yellow/black to the truck's red/orange is how the EATC tells the HVAC blower motor that it is OK to operate. It has nothing to do with the compressor clutch.

For 2000-back like yours, the purple wire controls the clutch directly. There are a series of switches that all must be closed for the power to get from the purple wire to the compressor clutch solenoid. However, you are seeing 12v difference across the clutch solenoid, so that all appears to be working. It also means that the clutch should be operating.

 

why did you delete that i was going to try that when i got home....

 

could it be a bad A/C relay? it sounded like it was chattering when i opened the power distribution box under the hood......could that do it?

you would think that the clutch would be operating.....espically since i have put power from the battery to it directly and it engages......

 

This is what is confusing me. Basically, you're saying that putting ~12v across the clutch from the battery makes it operate but ~12v across the clutch from the harness does not. How can that be?

 

Because it was based on the idea that you had 12v on both sides of the clutch connector. However, in a later post, you corrected that to say that there is a 12v difference between the 2 wires.

So, I saw it as no longer relevant and deleted it to avoid confusion.

 

ahhhh ok i understand now! sorry....

 

i dunno.....doesn't make sense to me! i will double check it when i get home, and i will put a meter on each side of the plug to double check.....

this a/c thing is bothering the **** out of me.....

could the compressory be bad.....and how would i tell if it was bad?

 

It doesn't matter if it's good or bad if the clutch can't engage to drive it. You need to resolve that before throwing any more parts at it.

 

ahhh true that.....

could it be a bad A/C relay? it sounded like it was chattering when i opened the power distribution box under the hood......could that do it?

 

There is a WOT cutout relay on your 97 that must be closed for the clutch solenoid to get voltage. If the relay is chattering, it is either a bad relay or there is a wiring error somewhere. You could try swapping it temporarily with an identical relay in the box. That should tell you if the relay is at fault or not.

 

alright i will try swaping that out.......it looks to be a SPDT relay......

would you know were the wiring error could be by chance?

 

Can say because I can't see it.

 

true that......man i wish you lived closer

what gets me is the efan and everything else comes on like it is susposed to when the HU demands a/c....

 

Bob, in looking over the relevant '97 wiring diagram I was wondering something: could a blown A/C clutch diode either affect or prevent proper clutch operation?

 

I'm no expert but I don't think so. Here's the way I see it. If it's shorted, it will take out the fuse. If it's open, it will just pour a bunch of current into the circuit every time the coil field collapses. That's not a good thing (arcing) but the clutch should still function, at least in the short term.

 

I follow you (I think). As far as you can tell, the diode is there essentially just to protect the rest of the circuit when the clutch coil field collapses. It does not have a role in execution of the circuit (i.e., clutch engagement).

 

i pluged the connector in and then jumped a + wire off the battery to the B/Y wire and the clutch engaged.......i also OHM'd out my ground wire from the clutch to the chassie ground and it was good.......so that at least means it is a power problem right

 

i also swapped out the A/C WOT relay with a like SPDT relay and it still didn't do anything different...

 

Yes, I think it provides a circular path to allow for the dissipation of the induced current to protect the WOT relay and other switches from excessive arcing.

 

If it engaged when you jumped B+ to the black/yellow and it doesn't engage otherwise, then there must not be any voltage present on the black/yellow from the clutch control circuit. However, I'm sure that you said there is 12v across the compressor clutch coil from that circuit with the A/C on. How can both be true?