Engine Fans Stay On (FIXED) - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 07-24-2007, 05:30 PM   #11
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I believe the A/C system has two different pressure switches. The correct one will have a Red/Black & Black/White wire going to it.
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Old 07-27-2007, 09:08 PM   #12
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Ok, I disconnected the low and high side pressure connectors, one on the drier and the other just past the compressor by the condensor and fans. I got code 530 I guess from doing this.

Reset code and still have fans on and PCM reading high pressure. No more code.Coolant at 194. Do I need to get new high side switch or do you think it is PCM malfunction? A/C system is empty. I will swap PCM this weekend but I don't believe this is the problem.
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Old 07-28-2007, 07:13 PM   #13
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Swapped pcm and same problem. I suspect now highside pressure switch went bad. It looks like it should be easy to unscrew the switch from the line. Anyone know how it is exactly removed?

Off to the junk yard tomorrow!
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Old 07-28-2007, 07:43 PM   #14
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Did you disconnect the wires going to the switch?
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Old 07-28-2007, 07:46 PM   #15
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Quote:
Originally Posted by Technical Ted
Did you disconnect the wires going to the switch?

Yes I did. Fans still on and got code 530 after doing that.
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Old 07-28-2007, 07:50 PM   #16
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Was that the switch with Red/Black & Black/White wires going to it?
If so are those the only wires or are there more?
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Old 07-28-2007, 10:53 PM   #17
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I disconnected a red connector going into the back of the compressor as well as a connector(Blue) going into what I believe to be a switch on top of one of the freon lines. This was to the right of the compressor by the condenser and engine fans.They both seem to be connected as the wiring runs to both of them. I din't take notice to the actual color of the wires but this is the only ones I saw other than the one on the drier (low side).

I don't know how this switch works and wonder why it would tell the pcm that there is high pressure when in fact the system is empty except for some air. I even tried banging on switch with hammer to see that that would do the trick. It didn't.

I just need to know how I replace the switch. Does it screw out by hand or do you take it out with a wrench. I looked at it and I can't really tell. Looks like it is welded into the line but maybe the switch is removed by twisting.
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Old 07-30-2007, 01:49 PM   #18
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I think I'll try one more thing. I'll reset pcm and before powering back up I'll disconnect connector going to high pressure switch. This way on power up I'll probably get code 530 but pcm should not see high head pressure.
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Old 07-31-2007, 08:06 PM   #19
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I disconnected battery and all a/c pressure switches and wiring. Reconnect battery and I fire it up and fans still come on and high head pressure. At this point I am stumped!

I start thinking, both relays can't be stuck on. Then I try to get compressor clutch going by jumping the connector at the drier. PCM see a/c request and clutch engage, but no compressor clutch engagement. Then it hits me, must be a wiring problem to high pressure switch.

I follow wiring and find a cluster of wires rubbing the belt. Not good I think. I look closer and I see metal and melted wire housing. WTF. One wire is totally broken, a black one. That must be the problem. I wrap the other wires as they were so close to being destroyed and repair broken wire. I wrap with electrical tape and place back in what is left of the plastic housing. I position the wiring harness so it is not going to be struck by the belt or anything hot.

I fire up and no fans. Check PCM and head pressure is normal. Case Closed!

So apparently by default, the PCM will activate the fans when a signal is lost from the high pressure switch.
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Old 07-31-2007, 08:21 PM   #20
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Good find.. Glad you finally got it fixed

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