odonnell

I took off my cooling fan so I could put on a 6-bladed one, and after realizing the new fan wouldn't clear the lower radiator hose I reinstalled the old assembly for now. Of course, I had to reattach the wiring. And you would think that it wouldn't be a problem...

Nope, I have a battery drain problem now. Anyone know of any common failures relating to the cooling fans staying on? They come on at temperature just fine.

V2Rocket

fan switch in rad or the relay

odonnell

Damnit, I replaced both less than a few months ago. Any good way to test the relay with basic tools like a multimeter?

After a few mins the fans come on. So wouldn't that rule out the fan switch?

Sorry for the barrage of questions, but I guess the most important one is... could either of these fail just by me unplugging/replugging the fans?

EDIT: answered a few of my own questions
http://www.clarks-garage.com/shop-manual/cool-01.htm

Dougs951S

Michael, I had an issue similar to what you are describing last time I swapped my fans due to trashed bearings. At first they were not coming on at all, and then I couldnt get them to turn off. I ended up resoldering my fan relay which fixed the problem for good. Make sure you press the connector onto the radiator temp sensor REALLY well, and also plug and unplug the fan relay to make sure its seated well. We can check it out this weekend and get it taken care of.

LP944

Im having the same issue with mine, just started to run until the battery dies. Its been 3-4 years since I replaced my thermoswitch butI doubt thats the gremlin.

As for replacing the relay, which relay would be the one to fit in the early cars? Hopefully not the $200+ option!

I have heard you can unplug the relay, take the cover off and clean the contacts?

V2Rocket

If you are really having wiring trouble, it's really easy to make a new fan circuit with stock functionality...did it recently for a customer's car whose wiring was trashed. Few feet of 14 ga wire, few feet of 18 ga, few spade connectors and a relay are all you need.

LP944

Ill see what condition the relay is in and see if it is salvageable.
Does anyone have a definite on which cooling fan relay to get? All I can find is this :

http://www.944online.com/cgi-bin/ASI...lectrical-9441

LP944

Doug,

What exactly inside of the relay did you need to solder, going to give it a try now. It was a small white box like relay correct?

odonnell

Sounds like a plan. If I have time this week, I'll go through and test the relay/thermofan switch using a 12v source and a multimeter. It seems straightforward.

The $200 one is for late cars, no worries there. You can test the relay by following the steps on Clark's Garage.

Keep us posted if you find a good source for a new fan relay for early cars. PP didn't have one and I'm wary of a lot of those online auto part storefronts that claim to have every which part...

LP944

I believe the part the PP is selling and 944online are correct, but apparently another updated version of the original small ones. The most confusing relay to find..

odonnell

The PP relay ($200+) is for late cars. I couldn't find the early relay. The 944online part looks right, but that's still pretty pricey. Doug, I might have you walk me through repairing my relay if in fact that's the problem....

Dougs951S

I'm pretty sure somewhere in my slew of past threads I documented the repair of the relay. If not, its really easy and I can show you how to do it in 5 minutes. I'll bring my soldering stuff when I come up. As far as sourcing the relay, yeah they are pricey. The one on 944online is the correct one, (still less than half the cost of one for a late car!) and they are the only ones who carry it as far as I know. Best bet, if it is the problem and we can not repair it, might be to try to source one from AustinVeedub or baring that, making a whole new fan circuit using a cheap *** 4 dollar generic relay and some wire. In any case, I more strongly suspect the thermoswitch, despite it being new.

william_b_noble

I have the complete central electronics unit with all the relays from an 87 S, if you get desparate

odonnell

Thanks guys. Here's an update:

I reattached the connections for the fans, and made sure the wiring itself was kosher. Had a friend jump me and then went for a spin.

Usually I can hear the fans come on, but I really didn't this time. Temps were between 50 and 75% which confirmed this. When I parked, the fans were only at low speed.

Doug's thermoswitch theory is looking better and better. I'm just 99% sure that whatever the problem is came from a result of my tinkering the other day, and I don't see how the fan switch was affected.

EDIT: It sure as hell is the switch. I went out 15 mins after the car was shut down (usually the fans quit at that point) and the driver's side fan was still spinning. I quickly jacked up the car and pulled the contacts on the switch, immediately stopped spinning. I guess I'm going to be limited to short commutes for the next few days.

Would you guys recommend the 75C or the 92C switch? I'm in Texas and it gets up there, especially in the summer months.

V2Rocket

75c.