bonnogo

Hello folks, I got a strange one for my 1983 944.

I'm having random electrical bugs and my hypothesis is that there is a bad common ground somewhere around the fuse box/stearing column.

Symptoms: cooling fans only work intermittently. I've gone through all the testing with relays and switches and etc. Sometimes they work perfectly and sometimes they don't come on high when the engine gets hot. I always test this before driving by seeing if switching on the AC activates the fans. If it does, I'll be fine, if not, it's a no go. I can take it out and drive it around with the fans working, park, and come back the next day and they wont work, then maybe a day later they spontaneously will. Possibly related to this is my wipers. They are possessed. They like to come on when I use my turn signals or even just when I turn. Sometimes they'll wipe for no reason at all. At the moment, they are stuck on low wipe no matter what so I pulled the fuse. I recently discovered that I have no wiper issue when the fans aren't working, but the wiper issue comes back when the fans are functioning. I have replaced the ignition switch in the last year or so as an early step to trying to fix the fans.

I'm hoping someone with experience with these electric systems can point me in the right direction before I lose my mind. I can barely see the fuse/relay box without jacking the car up. Everything in the cooling system is functioning. I had been thinking the issue was the relay seat for the fan relay since previously jiggling things around down there would get them to come back on, but that doesn't seem to be working anymore. The connection (no pun intended) between the wipers and the fans is a new realization.

There must be some other common circuit or something, right? Maybe a common ground? Would it be under the dash or behind it?

Dan

walfreyydo

Have you tried testing the fan relay, thermo switch, resistors and fans/wiring? This is where I would start before jumping to any conclusions about your wipers, as it may be coincidental.

You should read through clarks, specifically the cooling fan troubleshooting guide and test all the components of the cooling fan system that I listed above. I always recommend people read through clarks before posting.
http://www.clarks-garage.com/shop-manual/cool-01.htm

You wiper issue is probably related to the stalk, a separate issue likely
https://www.pelicanparts.com/techart...eplacement.htm

Google searching "Porsche 944 <question/issue> forums" will reveal alot of other threads and information without having to post a separate topic. These cars have been around a long time and there is (usually) a ton of already previously answered threads. It just requires some reading and research.

If your fan relay tests bad, F9Tech makes a solid state fan relay which is much less failure prone. They also make DME relays and DME computers for our cars.

Dr. 914

I would first replace the fan switch in the radiator

bonnogo

Thanks. I did follow Clarks Garage guide extensively and do a lot of forum research when I originally tracked down the issue. Based on his guide I'm 99% sure the issue is/was the relay (drivers side runs on low, high speed doesn't come on with high temp or when AC is on). I took the relay out and tested it and it's fine. I strongly suspect something in the wiring to/from the relay. I was going to replace the relay seat but moving those wires around doesn't help so I think the connection problem could be anywhere from there to the fans.

I'm open to the idea that the issues aren't actually related, but they do co-occur. I'll check out the wiper stalk though.

bonnogo

Clarks says a bad thermofan switch would cause the fans to run continuously. My symptoms are described by a bad relay, but I tested it and it's fine. Might be worth replacing anyway (even though the PO said he did) but I remember eliminating it when I was really having this problem last year.

orig944

When you test with the AC before driving and it fails, does zero or one fan turn on?

bonnogo

I never have any issues with the one fan (drivers side I believe) running on low.

orig944

Just to clarify, with a cold engine, AC off, and ignition on, the fan does not run. You turn on the AC and the left fan runs at low speed. And if you run the car until hot, the left fan comes on at low speed. This, of course, when it is not working correctly. Do I have this information correct?

Tiger03447

Way, wayup under the dash on the drivers side, there are two receptacles for a multitude of grounds. There must be about 10 on each receptacle . I haven’t removed them from the dash on my car yet. BTW Ftech 9 does NOT make a relay that will fit our early cars. The later cars use a completely different relay setup than ours. I have the dash out of my car, due to an under dash fire, and I’m still intimidated by the multiple ground set up. Good luck😀

Tiger03447

I may be wrong about the Ftech9 fan relay. Ours is a small relay. I think his is much larger and only made for the 86 and up cars. Mea Culpa if I’m wrong.TIA

bonnogo

Nope that's not right. Left fan runs on low with engine on and AC off once it warms up - it turns on and off as normal. When everything is working, both fans will come on high if either 1) I turn on the AC (happens with engine cold, warm, or hot) or 2) both fans will also switch on high when the engine gets hot. On the other hand, when it's not working I can't get the fans to run on high by either 1) turning on the AC or 2) letting the engine get hot, but the low fan always functions.

A few times I have been caught in traffic on a hot day and noticed the engine getting too hot and the fans not coming on high. Whenever this happens, I can't get the fans to come on by switching on the AC either. Previously, I could reach down and push on the relay and/or jiggle things around and that would sometimes get the fans to switch on, but that's not working anymore (and it was never a sure thing). As a result, I always check whether the AC will get the fans to kick on high before leaving the house. So far (knock on wood), the fans have never stopped working in the middle of a drive. It's always either they work or don't. Recently I've had a long streak of no problems, but they just started reoccurring in conjunction with the wiper issues.

bonnogo

I really hope I don't have to go through all that trouble for an intermittent issue, but it might be worth it. Is that by the firewall? Do you have to remove everything including the instrument cluster and center console to get to them?

orig944

Got it. Getting close now, but another question. Does the inside AC fan come on when you turn on the AC?

bonnogo

If you mean the blower for the AC in the interior then yes, that works too. Although only when the fans work. If the fans don't work the blower wont work either.

orig944

So the single point of failure that I can find that would cause the symptoms as I understand them is a connection on the back of the fuse/relay panel at location G7. That is terminal 7 in plug-in block G on the back of the panel. It has two black with violet stripe wires connected to it, and these both must be disconnecting intermittently. There is another test to confirm this. When the system is not working, with ignition on and A/C off, check the fresh air fan (heater fan) to see if it works. If it does, I'm wrong for sure. If it doesn't work, put your chiropractor on speed dial. I've never had to pull down the panel, but I'm sure it is a total PITA.