Fans running after engine is off?

[Gawernator]

So, today while dealing with my cooling system I was paying attention to the fans as well. I wasn't sure if they were on while idling but after turning off the engine could hear and see them stop, so that's working. However even with the engine at the max allowed temperature the fans were not running afterwards? I remember on my 1983 944 the fans would sometimes run for up to maybe 30 seconds after I turned off the engine. I don't think this has ever happened on my 86. The words "thermo" and "switch" pop into my head, but I'm not sure lol

[Dave Colangelo]

both my 88 924S and 87 944 run afterwords depending on outside temp and engine temp. I will say that I have never had the situation where the car and fans go off at the same time, the fans always run a bit after I shut the car off no matter how short of a time it exists.

Regards
Dave

[Gawernator]

So do I have a switch or something to replace

[John_AZ]

You could replace the radiator thermo fan switch.

There are 3 different temp ratings-75*, 85* 92* -usually just get the one now in the car.
Porsche 924S/944/968 Cooling System Miscellaneous - Page 1

The early 924s had a problem that the radiator fan switch would keep on too long and drain the battery.

It can be changed by just removing a bit of coolant and getting a tool to turn it out. Do not cross the threads!

GL
J_AZ

[Gawernator]

Thanks John

[pfarah]

That's also on my to do list (this spring).

[Jfrahm]

I think there is an interlock with the hood switch to shut the fans down if you pop the hood. You might check that switch in case that is your problem. Being a German car there might be separate hood switches for the alarm, light and fan so check all that you can find.

[Gawernator]

Are you sure? I was under the impression the fan could operate anytime the battery has power, which is why the Hayne's manual often recommends disconnecting the battery

[Panzer909]

Yep, sounds like the thermo switch. Easy fix.

My fans still run even if you turn it off & lift the hood.

[ernie9944]

[QUOTE=Jfrahm;7271501]I think there is an interlock with the hood switch to shut the fans down if you pop the hood.

No such thing on 944s/968s as a fan interlock when you open the hood.That why peoples working around their fans are advice to disconnect the battery when doing so.

[Jfrahm]

Ahh OK. There is one on the 928, when it decides to run forever you just pop the hood. Good to know.

[Panzer909]

One more expensive & overly-complex do-dad to break on those 928s.

[Gawernator]

I'm really lazy right now. Does anybody know the right part number for an 86

http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=951-606-481-00-85-M2&catalog_description=Thermo%2Dfan%20Switch%2C%20For %20Radiator%20Cooling%20Fan%2C%20%38%35%2F%39%33%2 0degrees%20C%2C%20%39%34%34%20%28%30%32%2F%38%35%2 D%38%38%29%2C%20%39%34%34S%32%20%28%31%39%38%39%2D %39%31%29%2C%20%39%34%34%20Turbo%20%28%31%39%38%36 %2D%38%39%29%2C%20%39%36%38%20%28%31%39%39%32%2D%3 9%35%29%2C%20Each%20%20

[nightheart]

Originally Posted by Gawernator

I'm really lazy right now. Does anybody know the right part number for an 86

Pelican Parts - Product Information: 951-606-481-00-85-M2

Get the one already in the car, so it matches the thermostat. I ran a lower temp fan switch than my thermostat for a while and it played havoc with the cooling system. The car runs cooler now, with a higher temp fan switch that matches my thermostat. 2 cents and all......

[Gawernator]

How do I know what temperature? PO replaced my thermostat in 2011 with a genuine Porsche one

[nightheart]

If you have the receipt for the thermostat, it might list a part number. Surest solution would be to replace them both. I'm sure thats not what you wanted to hear. It wasn't a disaster running a different temp thermoswitch, just not right. The fans kicked on before the thermostat opened to allow cooling.

The fans are auxiliary cooling if the antifreeze can't do the job alone. When they kick on before the thermostat opens all the way, its like putting the wagon before the cart. If you know who did the work, you can call them ask them what they normally use. Also if it was done with porsche parts, they probably stuck to OEM cooling and replaced the waterpump with the "normal" one for the car.

[nightheart]

My fans used to kick on at 2 and half bars (early car). With a higher temp thermofan switch, they kick on at 1 and 3/4's bar. When I do the waterpump at the next belt change, I'm replacing both with the lowest temp setting thermostat and thermofan switch. As for right now, getting the thermostat out just sucks too bad with the waterpump still on the car.

[John_AZ]

Originally Posted by Gawernator

How do I know what temperature? PO replaced my thermostat in 2011 with a genuine Porsche one

You could remove the fan shroud and possibly see the temp number on the side of the thermo fan switch. (my replaced early example shown)



J_AZ

[Gawernator]

Thanks again. Well my invoice is missing but I remember the thermostat being replaced and the Volvo shop used genuine parts. I'll go look on the side but I have a feeling already that I know which one it is

[Gawernator]

Okay, apparently this is moot because after making it through some insanely bad traffic today the fans came on after I parked and turned the engine off. So maybe it does work after all lol but the engine must need to be pretty hot.