924Board.org

Dean47 · Joined: 02 Nov 2012 Posts: 13 Location: Idaho

I have a 1977.5 924 na. Can I bypass the cooling fan resistor or would that cause other problems? Fan turns very slow unless I bypass it.

Ozzie · Posted: Sat May 25, 2013 5:43 pm Post subject:

The bypass is supposed to happen via a relay when the ignition is on.
Check the relay first.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Dean47 · Joined: 02 Nov 2012 Posts: 13 Location: Idaho

Ok thanks, fan stopped working altogether unless I bypass resistor. Would it be ok to relocate resistor cause it is always wet when it rains, or does that matter

Paul · Posted: Sun May 26, 2013 12:40 am Post subject:

The fans when the ignition is on have two paths to ground, one through the relay which is a low resistant path and one through the resistor.

When the ignition is off the fans only have one path to ground through the resistor. This allows the fans to run slower and quieter when the car is parked and the radiator fan switch is calling for cooling.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Dean47 · Joined: 02 Nov 2012 Posts: 13 Location: Idaho

Grounds are all good. ( first thing I checked) fan only works if I bypass resistor car running or not. I don't care about the noise so would it be ok to replace relay and just bypass resistor?

Paul · Posted: Sun May 26, 2013 2:15 am Post subject:

Replacing the relay will probably fix it, no need to bypass the resistor.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Dean47 · Joined: 02 Nov 2012 Posts: 13 Location: Idaho

Thanks for your help. I can re build motors, but I've never been good with electronics! This is off the subject but how do I put up a pic of my car by my name like everyone else? I know stupid question!

Mudd · Joined: 27 Aug 2012 Posts: 78 Location: Cincinnati,Ohio

How about replacing the resistor. My resistor on my 78 discintegrated because of its location above the radiator. The replacement was pretty cheap.
_________________
1978 924
1987 944

Dean47 · Joined: 02 Nov 2012 Posts: 13 Location: Idaho

I'll replace resistor too then and relocate it's in a bad spot water soaks it everytime it rains or I wash it

Ozzie · Posted: Sun May 26, 2013 8:04 am Post subject:

Paul · Posted: Sun May 26, 2013 9:08 am Post subject:

2 paths, one through the relay and one through the resistor. J26 is the relay, V7 is the fan motor, N39 is the resistor, and F18 is the radiator fan switch. Note there are separate fuses. You are correct the relay and the resistor is on the + side of the fans.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Dean47 · Joined: 02 Nov 2012 Posts: 13 Location: Idaho

Thank you that was very helpfull, I understand it now. Thanks