Coolant issue....how to troubleshoot

[daveimme]

Well, wife got back into town last night around 7 (still daylight) and the temp was over at 3/4 (of course, she had a/c on). So, I popped the hood and played some hoop with the boys while it cooled. 20 mins later got to it, cranked up and it was at the 1/4th mark, no fan on......temp went up to just past midway (at the normal rate, not real quick) before the fan kicked in. Prior to that, no fan on at all (normal, right). I could see it was cooling a little....*but* then I flicked on the a/c, and while it was working (cooling the interior), the second fan (left one, when standing in front facing engine) did NOT come on. Not normal.

This morning, had to hurry to drop off one of the boys at football practice, and forgot to check coolant level (when cold) just to be safe.....and drove off....traffic was crawling on the interstate for about 6-7 miles and though, I did not use the a/c, the temp went up to 3/4th, and I think the fan came on (I'm deaf, but think felt it), and after traffic picked up got back down to about the 10:00 position, which has been the normal position.

So, what do I look at? Did the fan die? Can someone tell me where to look to troubleshoot?

[Lawrence Coppari]

First thing I would do is determine whether the left fan is getting voltage or not when it is supposed to be on. Get a voltmeter and see if the line going to it is hot. You probably can do this test by merely turning the ignition to on (don't start it) and turning on AC. It is either not getting voltage or the motor is shot. Another thing you could do is run 12v directly to it and see if it runs. That would be an alternative to the voltmeter test.

I don't know how the fans on a 944 NA work. With my 951, they are either both on or both off. I understand this is not necessarily the case with NA 944's. Do the fans have separate fuses?

My fans will come on with the ignition off if the coolant temperature in the radiator is high enough. There is a thermostat in the radiator on the driver's side. If I pull its leads and short them together, both fans run.

[daveimme]

Well, I went by my mehanics since I was going that way on an errand and, though, he was not there, a mechanic that works in the shop next to him was. He knows a little, so hooked a wire from battery to fan and it came on fine, so fan motor is good. He looked at the thermoswitch and wiggled the plug a bit. I then cranked it and with the ac on, the other fan came on.....Temp was up in the 3/4th mark area; it's so dang hot out there!!!

So, I left the ac on for the drive back to the office, and the temp slowly rose up, so I shut it off and sweated it back to the office, and the temp did go down a little (maybe to the 1-2 o'clock position), back to the office. Still not where it should be.

What I changed about 2-3 months ago:

Lower temp thermostat (160 degree) and lower temp thermoswitch.

This kept the temp down for a good while...til, of course, let the wife take it out of town. Pure coincidence, but these things appear to always work out that way. I'm going back over to the shop after work and maybe bleed it and see if that helps. The coolant level is fine. Yes, the fans appear to have different fuses as my fuse box wiring diagram shows (#3 radiator fan, #5 air conditioner condensor fan).

Correct me if wrong......

When crank from cold; no fan comes on, right?

Temp get to certain temp, right (drivers side fan) comes on, right?

When A/C turned on, left (passenger side) fan comes on, right?

I know fans work, but still wonder if the passenger side fan has a faulty connection OR air in the system, right???

It's so dang hot out there, it just ain't funny!

[SoCal Driver]

Was a remark in a recent thread about the fan relay being replaced with the wrong relay.

In looking at the wiring schematics (Pellican has the 83 electricals in it's tech section) there are two fan relays available. One single pole for non AC cars and a double pole single throw for the AC cars. Four pins verses six pins.

Each fan has it's seperate fuse. The fuse/relay listing again in the Pelican tech section will tell you which and the amps.

Both my fans come on and off at the same time without the AC on. When the AC was working one fan would come on with the AC and the other would cycle with the engine temp.

If you can find them get a set of the six bladed fans and replace your three bladed units.

[daveimme]

I thought about the 6 bladed fans, but don't know where to find them, because down here it's hotter 'n hell! 102 degrees right now!

I've not touched a relay nor fuse in this car related to the fans or cooling system. I do know the fans do work, and it appeared after wiggling the plug to the thermoswitch, it came on when I first checked it. Do relays fail outright...or do they fail slowly; working intermittenly? I would guess relays would be the place to start.....I did print out the fuse box and relay schematic, so will look at that again (looked at fuse schematic a bit ago, but not the relay).

Thanks for the tip, and will check it out this evening...

[SoCal Driver]

Pull the connectors to the temp switch on the radiator and remove the rubber cover. Take a pair of pliers and squeeze the slip ons a bit so they are tight on the temp switch's pins.

Yes remove the rubber cover or what is left of it.

Had the same problem -- once.

[daveimme]

Rubber cover and connecter were quite solidly attached....Checked for power to the cooling fan (the manual refers to 'cooling fan'...is this the one on the passenger side, or should it say 'cooling fanS'?) I checked the connection of the 'cooling fan' relay and then the passenger side fan came on. Drove home from shop and the temp reading was as accurate as it has been. This morning, get in for the drive to work and I can feel the second fan come on as I ran the ac....so.....

I have to say that the 'cooling fan' relay is going out...they do go in and out, unlike a fuse, correct? Guess I will find a new relay and try that. One problem....how does one test a relay, besides plug in and see if works? Second, where do I find a relay for the cooling fan, since I've never had to buy one? I will check pelican parts here first, of course.....

So, I think I got it pretty much narrowed down to the relay being the culprit....anyone disagree? Agree?