daveo90s4

Hi all,

Car is a 1984 3.2L Carrera with the rotary **** between the seats (no auxiliary red heater **** in that area)

I've been reading up on the intricacies of this overly complicated and trouble prone system so suspect I have quite a way to go before I get it all working properly.

So I've decided to bite off little chunks and attend to them one by one.

1st thing is to get my engine compartment heater blower working properly. It does work and spin properly when I put an external 12v power supply to the two prongs at the back. But I am not getting any voltage from the female connecting terminal, no matter what I do with any controls (engine off, ignition on).

The three engine bay fuses are good, as too are all fuses under the hood. The problem could be the (expensive) engine bay relay?

So I think my first issue to to determine if the relay is the problem. Please how do I test if the relay is the problem ("apply 12 v to blah and blah and you should get continuity between blah and blah)? (I do not know anyone with a good relay I can just swap in).

PSI can hear the servo controller when I rotate the between-seats **** but the cables don't move. I suspect the rod linkage underneath so will check that tonight. But could that non-moving linkage have any impact on the engine compartment heater fan not seeing power?

Thanks - trying to keep the complicated stuff simple!!

DaveO

Mark Salvetti

Can't help you myself, but start here. The link includes additional links to threads over at Pelican.
https://members.rennlist.com/imcarthur/Heatrelay.htm

Mark

daveo90s4

Hi Mark,

Thanks for the reply. I had seen that very informative article and various links in my research.

However this link is mainly about how to get the footwell (slave) blowers to work if the engine (master) blower is not working.

That's a bit downstream from the crux of my problem - which is figuring out why I'm not getting voltage to the engine compartment heater motor.

As I say, thanks for the link but I'm still keen to figure out how to text the relay (maybe I'll re re re read that artcle and other links to see if somewhere there is a relay test mentioned (as opposed to a reed switch bypass methodology)).

Any more help from anyone gratefully accepted.

Cheers

daveO

daveo90s4

Hi again,

I've edited a diagram to show, I think, the power supply sources to the engine compartment heater control relay.

I think there are two two prime sources:

1. Fuse 8 in the hood to pin 12 with ignition on (blue line below); and
2. The three fuses in the engine bay to pins 8,7 and 3.

The three fuses in the engine bay are 'bridged' at the power side.

So a good initial test would be to see if indeed the three fuses in the engine bay are receiving 12 V. Yes? No?

I would think with ignition on and auto heat **** rotated to some heating position I should be able to put my multi meter on to the power side of this three-fuse block and see battery voltage (all this on the upstream side of the problematic relay) - as indicated by the green line.

Thoughts??



DaveO

Mark Salvetti

Sorry Dave. I did see the emphasis was on the front blowers, but figured somewhere in there was something that would help. I guess the relay they were talking about was for the front.

Sounds like you've already done some searches, but did you find these two?

http://forums.pelicanparts.com/porsc...ituationt.html

https://members.rennlist.com/imcarthur/heattrouble.htm

Both seem to have a way of testing the relay (see Pelican post #15), and the Pelican article actually has a relay repair (although I'm not sure it keeps the rear blower).

I think the Pelican thread confirms your pin analysis, but it also tells you which ones to jumper to get your blower to work if the front controls are working properly, leaving the relay as the only remaining culprit.

http://forums.pelicanparts.com/porsc...ituationt.html

https://members.rennlist.com/imcarthur/heattrouble.htm

Mark

daveo90s4

Hi again Mark,

The additional info you posted was invaluable - all of the electrics work exactly as they should without the relay and nothing works exactly as it should with the relay.

I suspect (!!) it is that expensive relay.

I think I will try the "Replacing Heat Controllers with 2 (5 pin) relays option and see if that gives me a cost effective fix. I see that it says in the wiring schematic "The front footwell blowers will always run regardless of rear blower" - I'm assuming this means they are independent of the rear (formerly master) blower and that it does not mean that they always run and can not be turned off.

A job for the weekend.

DaveO

theiceman

Yes Dave you are correct , it was poorly worded, according to the schematic orange heat lever has to be pulled to complete the circuit for the coil in the left relay that pulls over the contact to start the footwell blowers.

I would use heatshrink however to cover the solder joints in those pics. Unless you can somehow separate the board from those relays.

1986 Targa

FYI:

daveo90s4

Does anyone know if the '2-relay' option (as per above) is still applicable in an auto heat car - i.e. A car that does not have the physical orange lever?

I suspect it will, since I also suspect that with auto heat the physical orange lever has been replaced with an electrical equivalent.

Thanks all for your replies to date

DaveO

theiceman

Just not buying this.

daveo90s4

But Mr Iceman, do you have any views on the 2-relay option? Anyone else?

Cheers all,

DaveO

theiceman

im not sure what you are asking me . is that your design ? what views are you looking for . In the original schematic it shows an engine compartment controller.
if the internals of that controller are simply those two relays it looks easy to build and I would have It done by now.

My comment on the later thread is a don't believe having the exchangers at positive or negative pressure makes a hill of beans difference. if there is Co there , then its coming in , getting sucked in or getting blown in. Inner exhaust pipe is way thicker than exchanger metal anyway ensuring the outer exchanger skin would corode first by a long shot.

daveo90s4

I have implemented the solution I posted at #6 above and am very pleased to find that it all works perfectly on my autoheat car.

Thanks to all, especially Mark Salvetti, for your help.

Regards

DaveO

Mark Salvetti

You're welcome, Dave! Glad I could help. And great job building that new relay and getting it fixed.

Mark