924Board.org

[Schwami]

Greetings fellow 924s
Repaired A/C by putting R134 into system. success
Day later, left running 15 minutes and it pegged the temp gauge.
Drove home(engine cooled) and ordered a new coolant fan switch for top left of radiator.

System Tests:
1. looked at all fuses in main and aux fuse boxes. all good
2. jumpered the fan switch(by grounding) and only 1(drivers) came on low speed.
3. put 12V on passenger side fan and it ran at full speed. tested good
4. idled the car until the cooling fans SHOULD come on. Only the drivers side ran at low. checked the leads and no power to passenger side
5. ran A/C only the drivers side came on low. again tested leads, no power for passenger side.
6. I'm not getting 12 volts to the passenger side fan.

The fans came on previously with the warmer temps satisfactorily BEFORE I charged the A/C system.
When i turn on the A/C only the drivers side fan comes on(low). I believe that both should come on as before.
I read most all of the other fixes on here but the main fix seems to be the fan switch, but by jumping it to ground only turns on the 1 drivers side fan, not both as before.
I didn't mess with any A/C wiring nor cooling wiring.
Which relay is responsible? where?
Thanks for the answer to my puzzle!

summer is coming here and it will be one less worry.
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1979 924 Diamant Zweischicht.
Serial # 9249201031
XG 309 543 engine code.
2012 Golf Sportwagon TDI

[morghen]

Funny, having the EXACT same problem with my 931.
My 931 behaves exactly like yours..its just that I don't have an AC relay installed...the car overheats in traffic too as only drivers side fan turns on slow.
Problem is the relay missing in my case...and the drivers side fan only comes on because it draws power trough the command circuit with the relay missing or being broken.

I'd say you need a new AC relay.

http://www.pelicanparts.com/More_Info/94461511302.htm?pn=944-615-113-02-M504&SVSVSI=944M
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https://www.the924.com

[Schwami]

OK i got the relay (really FAST) from pelican.

I looked under the glove box and there was a not a relay there.

Looking at the Haynes manual I am guessing that it is above the fuse box. The closest that i can get is the blower relay#5. So i pull it(silver color) and notice that the relay i got from pelican has an "A" and "B" connection(black). this cant fit.
am i missing something here?
Thanks greatly
_________________
1979 924 Diamant Zweischicht.
Serial # 9249201031
XG 309 543 engine code.
2012 Golf Sportwagon TDI

[morghen]

Fuse box, third one from the top left.
I'm still waiting for mine from Rose Passion...it needs to be delivered to Italy to a friend(15 eur shipping), then he ships it to me for free...otherwise it would have been 80eur like 100 bucks shipping directly to me..crazy shit its like the would have to send someone on a horse to deliver the damn thing.


_________________
https://www.the924.com

[Schwami]

After i pulled out the suspected relay, I plugged in the new one and did all the tests again to see if i was successful. Alas, no change. no power to the pass. fan.

I'm thinking that i could route a wire from my foglights with a fuse and turn them on with aux switch.

Frustrated and tired. This shouldn't be so difficult
_________________
1979 924 Diamant Zweischicht.
Serial # 9249201031
XG 309 543 engine code.
2012 Golf Sportwagon TDI

[morghen]

Dont give up, dont botch the elecrics.
With the new relay the drivers side fan should kick in at full speed and when AC is on the other fan should be on as well. Make sure your AC can be on, meaning the compressor can operate.
Take a look at the glove compartiment relays as well, give them a clean and reinstall, thats what i plan to do on my 931 today reading that for you a new AC relay did nothing.
_________________
https://www.the924.com

[brian19600]

Schwami read this post, it talks about '79 A/C. It may help as I posted some electrical diagrams that are 79 specific.

http://www.924board.org/viewtopic.php?t=42191&highlight=
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78 924

[Schwami]

Wow, thanks for the link! This will help. Totally missed that post.

The A/C works good (Brrrr) with the exception of the Pass fan not getting ANY power.
I've put a multi meter on it and tested the ground.

The driver fan only works: (low only)
on thermo switch, A/C operation
after shutting down when hot.

Thanks for the support and inspiration guys.


Morning update.
Double checking the testing and I'm not getting a GROUND to the passenger fan. I think that it is the problem. According to the schematic in the other post, these wires connect in the loom or in the relay? That is my best guess where because the pass fan comes on when the radiator switch goes to ground.

on the schematic, where are the relays? i am not finding one behind the glovebox..???

[brian19600]

I would probe around both a/c relay and cooling fan relay and see what is coming in and out of them. You did check fuses I assume.
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78 924

[brian19600]

Here is a reference of the various relay part numbers and what they do. It's handy to have. It's good to make sure that the right part numbers are in the right places! I assume it's fairly accurate, but there were numerous changes in the early years in fuel pump relays and changes with a/c systems. So it may not be perfect.

https://web.archive.org/web/20090321193134/http://jenniferandjon.com/ABRacing/index.php?option=com_content&task=view&id=16&Itemid=51
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78 924

[Schwami]

Ahhh Mother's Day
And a beautiful day to work on your car!
I just replaced #3 so let's say it is a good unit from pelican.
From The schematics from above it looks like I need to test #1
I'm guessing, but to test I need 12v to the leads and listen for the "click".
Let's keep the frustration levels low today.....

Thanks Morgan and Brian. You at helping me and a new generation of 924 kids. Kinda like Mom's.
_________________
1979 924 Diamant Zweischicht.
Serial # 9249201031
XG 309 543 engine code.
2012 Golf Sportwagon TDI

[brian19600]

Not just a click, but you want to verify that ground is coming and leaving the a/c relay, and power is coming and leaving the cooling fan relay.

I'm guessing that this is not the case in one or both relays. Using a 12v test light/probe would be easiest.
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78 924

[Schwami]

http://i1383.photobucket.com/albums/ah283/schwami/IMG_1850_zpscabe0inb.jpg?t=1494693302

AS reading a book!!!1-11 relays.

I replaced #3 with the replacement from pelican. The old one is non recoverable because it was damaged during removal.

In other posts there isn't a relay in position #7 but i have one there.

Is position 1 the other relay for fans or blower?

The haynes manual is different by numbering and locations. go figure...
_________________
1979 924 Diamant Zweischicht.
Serial # 9249201031
XG 309 543 engine code.
2012 Golf Sportwagon TDI

[Paul]

Perhaps your car has a dealer installed A/C system. Post a picture of your system.
_________________
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.

[Schwami]

Problem solved.
i went to a salvage yard and pulled 3 of the relays out of other 924/944s brought them home and did tests on them.
BINGO.
Grabbed a few other relays for spares.
it was the relay in the #1 position.

Thanks to all who helped and hoped i could do this.
_________________
1979 924 Diamant Zweischicht.
Serial # 9249201031
XG 309 543 engine code.
2012 Golf Sportwagon TDI