NYFlapjack2

(I deleted - edited out of here my own misinformation and answered + questioned some more in my reply posted # 3 below....)

Original quest is almost:

1983 Cooling fan relay P/N's now are?

I have searched found many old topics close with some vagueness as photos are gone and the era of what car year-series missing... I plan to do a quick cooling fan relay check as it is easiest...then perhaps rad switch, then dig for the resistor under the gauge cluster in my era (1983 car) if required.
1983 N/A 944, 5 speed with A/C. 125k miles.

My coolant fresh (3 year old w/p, T & B belts), very clean, overflow jug clean, no - none coolant or oil leaks or usage...new rad cap too, I am thinking really don't have a cooling problem other than fan operation.

Re: Cooling Fans they both used to work fine. I could hear it run after shut off. Temperature gauge was always a little jumpy acting but seems accurate.

Recently low speed fan not working on key on or shut down hot.
No issues highway cruise temp gauge centered. Was seeing climbing gage
when sitting or in city driving. In garage last night confirmed gauge now will climb to 3/4 at gauge HIGH warning and then finally dual high speed fans turn on.

Those 2 fans on high will cool it in about 2 minutes to 1/2 way gauge mark and both fans shut off. No low speed until it cycles to high limit on high again-repeat.

Also with the dash A/C switch on, both fans instantly go to high (it is how I manually manage temp for commute in city for now). So that appears OK.

Question is the early 944 like my 1983...(photo my actual car part attached)
What is replacement now and common?

Pelican lists P/N 141-951-253-B-M5206 or the
141-951-253-B-M6206.... what is the difference?

Regards David
(name why?)

smokin_944

Have you tried the slow speed test as indicated on Clarkes? If you haven't, disconnect the thermal fan switch mounted in the rad, and jumper the switch. Driver side fan should come on at slow speed. If your driver side low speed fan doesn't come on (and you've checked the fuses) your problem is probably the slow speed resistor. That is what I think based on what you've said about the fans working at high speed. Let us know how you fare.

NYFlapjack2

Clark's a great help for sure, I already printed out the trouble shooting guide and wiring diagram had it with me. Yes I did do the jumper rad switch test in car...the low speed worked and the high with key on all OK...

I pulled the fan relay out of dash & did checks, it was and is normal operating ...so puzzled????

I see from the wiring diagram thermo rad switch grounds the LH fan.

I haven't read or understood this well is...
Does LH fan run at slow speed during driving at the low & medium temps and then a high temp set point kicks in both fans when higher level temp is sensed?

Then what signals the transition from low speed mode to high speed mode in normal car running operation?

Regards
David

smokin_944

Hi David, on the early air conditioning cars, only the driver side fan runs in slow mode, not the passenger side fan. What happens is that the high temp value of the thermal switch decides what the high temp condition is. By changing the thermal switch, you can change when the high speed setting is activated. There are 4 thermal switches that I know of for early cars: 823.959.481 a 75/70 degree, 823.959.481 D a 82/77 degree, 823.959.481 F a 92/87 degree and 823.959.481 E a 65/60 degree. In a high temp condition or when AC is activated, both fans work. You can lower the temp at which both fans come on by using a cooler thermal switch. I don't recommend the 65/60 which I used this year as it keeps the engine temps a little cool but the 75/70 Behr would probably work fine.

NYFlapjack2

Thanks for the P/N's....they have came in handy...
With the few things done/tested good.....
I have shook and pulled, reconnected each tab-spade terminal in these components. Plus I have sanded & contact cleaned the fan cooling relay too.

So I've probably engaged something better now....as I have it all working right for now ....high & low fans....but:

What I see is gauge temp climb all the way up to 3/4 or warning on dash gauge before the fans kick on. Then off at the 1/2 way mark.
This fan kick on point appears higher than in the past to me.

I am thinking perhaps the OEM Radiator fan switch is off...sluggish now..and/or perhaps the engine mounted coolant temp sensor (for my gauge snappy fluctuation?).

Regardless I have made a sponsor on here happy ordering both the 75 degree and 92 degree temp fan switch, a new Engine coolant temp sender too because I will have the system open so now a good time....

Another AC/Fan relay because the one I tore down is 25+ year old date code and a terminal is loose..OH and a DME relay........for combined shipping and you all have me convinced a DME relay in the glove box will keep me from needing a tow....

Thanks!

smokin_944

NYFlapjack2, I'm sorry I didn't read the first post properly... The fan relay Porsche p/n is 141 951 253 B (from 83-). It is the fan relay. It is a universal relay that is cheap to buy (5 or 6$ US) and also doubles as a rear defroster relay and a horn relay (only for the 83 year). The A/C relay is Porsche p/n 944 615 113 01 (as of 1984). The problem with these 2 relay units is their placement on the fuse and relay board in early cars. It seems most people don't know the difference between the two.

smokin_944

If you want the fans to come on earlier, you need to pick one of the 2 lowest value thermal fan switches, be it the 65/60 or the 75/70. Either of these will have the 2 fans in high temp mode before the first hash line on your gauge which is 80 degrees C (on an early car). My guess is that your present thermal fan switch is probably the 92/87 switch because the low temp fan comes on at 87 degrees C and the high temp condition is 92 degrees which is halfway between the second and third hash marks, 89 degrees and 97 degrees. This is probably the reason that the fans come on so late. The range of thermal switch temps available make it easy to solve this.