cooling fans, '83 944

air_head · 11-13-2001, 10:41 AM

I can't seem to get the cooling fans to operate correctly. When the engine heats up (only in traffic) I have to turn on the a/c to get the temp back down. Both fans function (when a/c on), new coolant (properly bled), new temp sensor, new cooling fan relay. If I bypass the temp sensor, the fan(s) rotate at a very slow speed. A reply from the PP tech guy suggested that maybe a resister had failed, but he couldn't remember the details regarding location, etc. Any clues? Yes, I have looked at previous posts, but they didn't seem to address this particular situation.

Thanks for your help.

jwolk1 · 11-13-2001, 12:50 PM

I feel for you, I had a problem on my 83' that took 2 months to fix - so needless to say, I became pretty much an expert on an 83's cooling fan circuit. You may have already reviewed some of my prior posts (if not you should). You do not have the same problem as I did, but perhaps I may be able to help.

If both motors are working when then thermoswitch is bypassed, and both fans are turning on with the A/C then you may want to look closely at your thermoswitch (with a lower temp thermoswitch the driver's side fan should go on when the temp gauage reaches the 1/2 mark, with the higher temp thermoswitch I believe it turns on around the 3/4 mark).

You should check your relays, as the picture and diagram in the 1983 owner's guide is not correct - here is my prior post on this www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=14445

Also, it could be one of the additional relays that are located under the glove box. You need to remove the piece below the glove box to get at them. Don't hesistate to contact me if I can be of any further assistance -

Jeremy
1983 Guards Red

air_head · 11-13-2001, 01:00 PM

Thanks for the feedback. My thermoswitch is the 92 deg (c) model, and the fan doesn't come on up to and past the 3rd mark on the gauge. As I recall (I've been casually chasing this problem for a few weeks), when I bypassed the themoswitch, it was the d/s fan only that rotated veerry slowly. I have looked at your previous posts, and I was surprised to learn about relays under the dash on the passenger side. I'll have a look. The wiring diagrams that I've looked at (Haynes, Pelican Parts info) confirm your views about relays, but I see a resister in the cooling fan circuit that I'd like to locate. Any ideas?

Ehab · 11-13-2001, 01:28 PM

92 degrees is 10 degrees hotter than stock ... you are literally overheating all the time. That happened to me when my stupid old mechanic put in a 90 degree thermostat ... I replaced it with the 72 degree one, and used a low temp thermoswitch as well, and now the car is much happier.

As for your fan ... if you get slow roration when you bypass the switch, that implies that the relay is dead or malfunctioning, try replacing it or swapping it with an identical one, and see what happens when you bypass the thermoswitch, the fans should kick in at full strength.

The resistor is there for the slow rotation, so it that IS happening, then your resistor is fine. Resistor are very very hard to burn out ... it is easier to break them physically than get them to malfunction.

Good luck.
Ehab

air_head · 01:55 PM

Is my thermoswitch/thermostat description unclear? My thermoswitch (the sensor at top d/s of the radiator) is 92 deg, same as the one that came out. Don't know about the thermostat, as I haven't replaced it just yet. And I have replaced the relay, and swapped back new/old/new. No difference. If I'm reading the wiring diagrams correctly, the d/s fan only should spin when triggered by engine temp, and both fans should spin when the a/c is on. And when I say slow rotation when the thermoswitch is bypassed, I mean *really* slow, say less than 100 rpm.

jwolk1 · 11-13-2001, 02:10 PM

Ehab's resistor statement is on the money. My mechanic and his electrical expert explained that it was unlikely to be a resistor when I started trying to track them down. I am assuming this problem just started, and that in the past the car ran fine. My d/s fan ran slow when bypassing the thermoswitch prior to fixing my relays (I didn't check it after - so I am not sure if it should do this). Obviously, something is keeping your d/s fan from turning on at the proper temperature. As I stated before the most likely culprits are a faulty thermoswitch (i.e. two prongs out of radiator) or likely the relays under the glove compartment. Good Luck -

Jeremy
1983 Guards Red

air_head · 11-13-2001, 02:51 PM

Well, things didn't work right when I bought the car. The fan(s) used to come on as soon as I turned on the ignition. I thought this was normal. Then, during our first trip in the car, it/they stopped working entirely (at least in response to engine temp), which wasn't a problem unless in traffic. And I realized I could turn on the a/c to cool things down when needed. So, after fuse replacements, and the other things I mentioned in my initial posting, we are at this point. The thermoswitch is new, so I'll root around behind the glovebox this weekend and see what I can find.