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Ac problem wiring check

7K views 10 replies 4 participants last post by  agatto2 
#1 ·
Hey All... so the 02 2500 ac is not working . Heres the question and heres where i am at in trouble shooting
all fuses ok
The relay in the engine compartment is working and getting proper signals
Low pressure switch jumped out
Clutch is engaging when wired direct to battery
proper voltage
High pressure switch is good
Getting ground from pcu

i jumped the wire from terminal 30 to 87 for the relay in the engine compartment and still had no voltage on the green (compressor positive wire )

I have no breaks in the green wire up to where it enters the large bundle near the fuse box

So heres the question or the direction i am going.... i have a malfunction from the relay terminal 87 to the clutch on compressor and i have to

a: take apart that relay box somehow and find the real problem... or
b: solder wire in on that side of the relay and basically kinda hot wire it which should work.

I prefer to fix it proper however i am at a loss as how to chase that wire down inside the relay box in the engine compartment
 
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#2 ·
Take a close look at the connector on the compressor. Both wires on mine were frayed and touching/shorting right where they go into the connector. I had to peel back the wire loom and some tape.

Not enough slack to tape em, and I don't have access to another harness to butcher, so I separated them as best I could and lathered it in liquid electrical tape. Seems to be ok for now.

Sent from my LG-H831 using Tapatalk
 
#4 ·
Have you swapped the A/C clutch relay with another to see if that cures it? Also there is a 10 amp fuse to the right of the A/C clutch relay that may be blown. It provides the trigger power for the A/C clutch relay.
 
#6 ·
I have a 2007 2500HD and the clutch is not engaging... is it likely the compressor (clutch?) is bad and needs replacing, or is it more than likely a fuse or wiring problem? I was going to follow the mechanic 101 rule by replacing the easiest and cheapest first, but thought I would ask. Thnx
 
#7 ·
You should be able to ohm out the compressor clutch... there are probably specs somewhere on this site...
However the easy way is to hot wire a ground an positive wire to the compressor... if it pulls in pretty solid it is more than likely good
 
#9 ·
This is great advice... thank you... would you please give me a “search” suggestion, since I have combed through 20+ pages of possibilities with no success. I’m not one to start a thread without first trying to search, but the problem is getting frustrating.

The clutch does spin freely with my hands, so I don’t think its frozen... it seems more likely that there’s some sort of electrical problem... unless its own brains are fried. 'dunno;
 
#8 ·
I had a both wires frayed right at the compressor connector. They were touching ever so slightly. I just separated them and globbed on some liquid electrical tape and let it dry overnight. No problems in 10000kms.
If it happens again, I'll have to splurge and buy a new harness pigtail. Or butcher my LB7 harness.

Sent from my LG-H831 using Tapatalk
 
#10 ·
I had a both wires frayed right at the compressor connector. They were touching ever so slightly. I just separated them and globbed on some li
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quid electrical tape and let it dry overnight. No problems in 10000kms.
If it happens again, I'll have to splurge and buy a new harness pigtail. Or butcher my LB7 harness.

Sent from my LG-H831 using Tapatalk
More great advice, thank you... I looked at all the wires and they are aged and what I would consider “brittlish” but will take a closer look to see if there’s any breach in the coating... will also try wrapping them in electrical tape as a trouble shooting attempt.

Again, thank you.
 
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