87 924S - My 2 radiator fans do not seem to come on unless the AC switched on.

Here is story. 1) I am in south Florida. PO I bought the car from did not have any thermostat in the water pump. I took the car to a Porsche tech in Miami to replace my hose to the water pump / upper radiator and he installed just a gasket. Said in South FL on these cars it is better to not have a thermostat in. He also told me I needed to replace the radiator fan switch which I did myself with a new fan switch.

2) I took the car last week to my regular indy mechanic for him to check the switch and tamp gauge to see if it was accurate or not. He used a laser temp gun checking hoses etc....and my fans did come on then with out the AC turned on. I thought I was OK. He also said my temp was normal (With the laser gun the reading was 186F pointed at the water pump, and hoses with the car idling for a good 10+ minutes on a hot Florida day.) but my gauge was not showing accurate readings which the PO also told me probably was so through the 5 yrs he owned the car. PO replaced the engine temp sensor while he owned the car in the past 5 years.

--- Since then I am driving the car quite a bit and have not seen the fans come on 1 time w/o the AC running. Per Clark's garage the fans should engage at around 92C degrees which they definitely do not do.

* I have not overheated. When my gauge reads 97C w/o the AC unit on, like at a stop light it will get this high, I turn on the AC for the fans to get going. If I do not turn on the AC then the temp gauge will continue to read hotter.

It would be nice if I could do this myself and not have to take it in. Any suggestions where to start? Does the missing thermostat have anything to do with the fans not coming on?? I do not have a coolant leak that is noticeable at all from any drips but I do get some coolant odor into the AC sometimes.. sometimes I do not.

Thanks...
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one of your fans could be dead (or could be the relay).... you should be getting low-speed during normal driving.... both cases are a pretty normal occurrence.

 

If they were dead would they still go on when I turn on my Air Conditioning? edit: * Both fans run when the AC is on.
..

 

are both coming on when you turn on the AC?

your late car has multiple speed fans which are activated by the thermoswitch.

one or both should be running at low or high speed depending on what the thermoswitch senses as the engine reaches normal temp (depending on outside heat, traffic, etc).... and after you shut off the car if the thermoswitch is getting enough heat.

when the AC comes on, both fans automatically switch to high.

 

Yes. Both with AC .

 

you most-likely have a bad fan relay (a very normal situation).

it's good that neither of the fan motors are seized ($$$).

 

Is that this part-> 141951253B
Wehrle

 

i'm sure that's the right one. one last thing; check for a fully grounded circuit and your connections at the fuse box. I forget where the high amp fans ground out, but it should be on the firewall near the box. there's a good chance you'll have some rust building up there as this area of the car gets a lot of drainage, leaves build up, rot and trap moisture. you would do well to remove the battery and do a thorough clean up with a hose.

 

How do I check for a grounded circuit ? Where? & good connections at the fuse box is nearly impossible unless there is a way to bring it down without disconnecting any of the harness wires .... This is where I am a little lost..

 

i can't recall. I had the same problem with my '87 944 in like 1992. but i lucked out by just changing the relay. the car was just a few years old then and didn't have any further trouble.

btw, in 116 k miles it was the only part that was changed out besides oil changes, a fuel filter or two, cap and rotor and the spark plugs. no belts ever changed !! i finally i blew up after about 7 or 8 k miles of not knowing i had a slow oil leak, and never checking the oil.

 

OMG Thanks. I think some of my wiring there may be loose since I am also having a problem with my dash gauge light fuse. It keeps blowing out.

 

OK so first time for me trying to remove a relay to check the #s . Are they welded in or what??? It is not easy getting a solid grip on any of the upper bank relays let alone the Fan Relay which is upper left corner.

I pulled on this with fingers on top and bottom as hard as I could without thinking I would cause any damage to wiring and it did not even budge out of place. Any easy way to remove relays I don't know about like the "relay release button" or similar???

 

if it' sticking, gently remove the 7 or 8 fuses closest to the relay with your needle nose,
then work a flat head under the relay and gently nudge it loose.

http://www.944online.com/cgi-bin/ASI...lectrical-9442

http://www.clarks-garage.com/shop-ma...tefanoperation

http://www.clarks-garage.com/shop-ma...#laterelaytest


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It's possible that your AC relay is bad (only the driver's side fan runs when AC is off IIRC).

My theory is this: you're fine. The lack of the thermostat is keeping your temps down, and the fan switch is simply not being triggered. Or perhaps the switch isn't working.

Test the switch by unplugging the switch and jumpering the leads (completing the circuit), which bypasses the switch. If the fans come right on, you have a bad fan switch. Assuming your connections are all good.

 

"odurandina", This is my relay & fuse set up. http://ehadesign.com/~dsmith/fuse_&_relays_924s.htm

The relay in question is upper left hand corner. Getting in this spot is very tight and dry weather permitting I will get to this sensor.


sausagehacker: Both fans run with AC on , not just one. How can I jump the leads on this sensor to test the fans to start up with a warmed engine above 92C ?

I am all for installing a thermostat and it will get done asap.

Thanks, Austin