doug928

Well both cooling fans are not working and I'm at a loss as to why. I went out on a 200 mile trip last weekend and the passenger side was working and today both sides are not working . I even jumped out the fan circuit to see if I could get them to run - no luck. Would the temp sender cause this if it went bad? or could it be the "ecu" at the passenger side going bad? I'm at a loss as to why this is happening. Any help would be greatly appriciated.

ErnestSw

When you say you "jumped the fan circuit" what do you mean? Where did you put the jumper?

WallyP

Each fan has a fuse. It is not unusual for the fuse connectors to develop high resistance - in fact, I pulled a melted fuse from my '90 GT today!

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doug928

Ernest - On the passenger side fan control unit there are two connectors which control the fan and a/c operation. on the bottom plug there is a blue wire. If you pull this wire out it will simulate a fan fault and cause the fans to run continuously when the key is turned in the ignition.

Wally - I checked the fuses and they're both fine.

wds928

Does the A/C work? Had your problem and no A/C a couple of months ago and solved it by cleaning the battery terminals, especially the positive at the battery, plus the 3 wires that come off the battery terminal.

The fan controller needs 7+ volts at connection 6 and 8 I believe (with 7 as a ground). Mine measured 3+ when I started, no fans, no A/C. Once I cleaned the battery terminals, I had 7+ volts and everything worked. The testing procedures are in the WSM, Section 19 I believe. Good luck.

doug928

Bill the a/c works great now - I just can't run it because the car will overheat eventually. I think it might be the output stage of the fan system but I need to check it further. I have gone through section 19 of the WSM's and when I checked all a couple of weeks ago things were fine. I just puzzled as to why everthuing suddenly stopped working.

Dennis Wilson

Did you leave the fan that wasn't working plugged in? If yes, it could have an internal short that has cooked the other components such as the relay.

Dennis

doug928

Well I may have found the problem. The plug which attaches to the output stage box had a loose pin - I say had because as I was doing the diagnostics shown on page 19-25 of the WSM's pin #4 fell off I also noticed that I was reading voltage between pins 3 & 2 with the ignition on or off ( about 12v and pins 3 & 4 which are supposed to read battery voltage were only reading about 7 v. Does anyone know if only the plug can be replaced. I know that the plug is part of the wiring harness but I thought that if I had a new plug I could resolder the leads together without removing the entire wiring harness.

ErnestSw

Check the voltage to the output stage. Start at the battery to fuse leg, across the fuses, out of the passenger side controller, and check the ground on the passenger's side near the jumper peg. You might want to jump from the peg to the fans just to make sure the fans work properly, but it's unlikely that both fans would fail at the same time. See whether there's someone near you with an output stage you can swap for testing.

doug928

Ernest - I was starting to check these voltages again when the female pin on the plug going to the output stage sheared off Pin # 4. It sheared off at the base of the connector so the only way I can test the output stage is to somehow make some temporary connections between the pins. Unfortunately I don't know which wire (from the harness) goes to Pin #4 unless I try and pull apart the plug end which I don't want to do yet. I first want to see if one of the Big 3 can sell me this connector - somehow I think this is going to hurt my wallet.

ErnestSw

Doug, would it be possible for you to take a picture of the connector in question? Many of these connectors are designed to come apart.

doug928

Here it is:

ErnestSw

Pin 4 is a battery voltage hot lead for fan # 1. Have you checked voltage between pins 3 and 2? That should be battery voltage also. 3 is ground for both fans. Looks like you'll have to replace the connector or at least splice in a new one. Bummer!

aircooler

Doug,

Call 928 INTL, or 928 SPEC. They may have a damaged/burnt harness that they may sell you the plug from.

BTW, I have been dealing with a one fan operation for a while. I have checked all the wiring and connections. When I came to diagnosing the control boxes, I just went down to my local Porsche dismantler and he let me swap out boxes. The first control unit I tried was the fan/flap control box under the pass side amp cover.

Voila! Both fans at low speed at operating temp.

Best of luck,
Mike

doug928

Thanks Mike, I plan on calling Dave/Jeannie tomorrow and see what's available. I hope it was the loose pin causing my problems and with some luck and some splicing work I can get the fans to run again.