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A few weeks ago (over a month) I posted regarding my A/C not kicking on when it was supposed to, then staying off for long periods of time (in 100 degree weather). It all happened after I had an oil change at Wallyworld.

They do the 15 pt check or whatever they call it, and test your battery. Within 20 minutes of them doing all this, the problem started. I had a few stored codes, which I cleared (EPROM read access error, etc).

I found that if I stepped on it the AC would work (clutch would engage), and so I did a lot of unnecessary WOT$ when gas was higher.

The dealership wanted $700 to replace compressor.

I had read about some folks on here finding out the little box that was taped on the line to the AC compressor clutch power cord was the culprit. I could not find it. Then one day I felt it in those cords.... tiny little white box wrapped in black tape: the A/C clutch diode. Sure enough, I took it off the line (it had alligator type clamps cutting into each line) and the AC clutch was engaging like a champ. Determined to replace it, in case it actually had a function I went to O'Reilly autoparts, and even to the Cadillac dealership and they knew nothing of it. Finally got a Chevy parts counter to give me a part number.

I ordered it, and when I received it I realized there's no way to know which way it goes? I should've taken notes.

The two lines in the cord that plugs into the AC compressor are green and black. The two lines in the diode... are white.

There's an X on one corner of the box, and a Y on the other corner (opposing). Knowing the function of a diode is to restrict current to one direction only I guessed it was from X to Y. but each of the two lines has one of the letters. So in essence I could assign X to black and Y to green, in one direction or another, and viceversa (4 possibilities).

So, I tried X to Y (flow), assigning black to Y [green to X], and the compressor stopped engaging. My check engine light came on too. I thought it was from me tugging on wiring. PCM P1660 Fan Circuit fault, I found out. So I looked and sure enough both of my fans were not turning.

This is at 11 pm folks. I traced all wiring, looked for fuses to the fans, and only found the relays and MaxiFuses. Distraught I was.

So I redid the wires to the AC clutch without the diode, and it still didn't work. I was very frustrated late at night.

In the morning I'm trying to figure out what I'm going to do to get to work, and I thought to look in the service manual for the electric chart to the cooling fans. In the little box eplaining the maxifuse for the cooling fans, was another circuit breaker: the AC compressor fuse 10Amps. I went to look for this fuse, and sure enough it was blown. I replaced it and cleared the codes (fans were working as they should).

So I'm running the AC without a diode. I have the diode, but need to purchase at least 3 10 Amp fuses, in case I need to find out the hard way which way the diode connects. My likelyhood of success each shot is 1:3 (assuming the one that blew the fuse is out of the way).

Help is wanted and appreciated!
Can someone send me a picture where the diode is located. I can't find it and need to replace it.

Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
19,658 Posts
Can someone send me a picture where the diode is located. I can't find it and need to replace it.
this thread is from 2005 - and died 15 YEARS ago
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