'84 944 fresh air blower

pholdredge · 04-26-2002, 10:10 AM

Hi all,

I am trying to debug a faulty fresh air blower relay circuit.

Can anyone tell me if the fresh air blower relay should normally get 12v at all times, even with the key off?

Also, where might I find the "fresh air blower interlock relay" shown on the AC wiring diagrams?

Thanks...

Paul

drew1 · 04-26-2002, 03:15 PM

Hi Paul,

I think fresh air blower relay gets 12 V when the key is in the switch.

I think interlock relay is behind the control panel in the center dash.

drew1

pholdredge · 04-26-2002, 06:44 PM

Thanks Drew.

I found and pulled the interlock relay and it did stop the problem. However I still have 12v to the fresh air blower relay with the key off - basically the entire voltage rail X (on Pelican's wiring diagrams) have 12v at all times (with all relays & fuses pulled, and key/lights/wiper switches disconnected).

Argh...

Paul

drew1 · 04-27-2002, 09:29 AM

ignition switch?

drew1

pholdredge · 04-27-2002, 12:38 PM

is the ignition switch different from the connector at the back of the ignition key?

I have recently found that with the AC blower lockout relay disconnected I have about 7-8v to the blower relay...which slowly creeps up in voltage to 12v...

are there any relays in the engine bay?

thanks...

Paul

pholdredge · 04-28-2002, 05:11 PM

I did, in fact, find the solution to my heater blower problem. At some point a
non-factory mobile phone was installed in the car and evidently some function of
it was in the trunk. The installer pulled +12v from the ignition wire loom in
two places (always-on 12v and switched 12v) and sent them both to the trunk via
a small ribbon cable. When they removed the phone bits they left the cable in
the small luggage box behind the right rear wheel - it is spring here and this
box flooded (about 150cm of water)...the connector eventually corroded and then
conducted the 12v onto the switched circuit which made its way to the blower
relay. I found this by removing all three connectors to position H on the back
of the relay board (quite obvious to find) and tracing which connections still
had 12v. The electrical conduction through the water in the luggage box explains
the very odd 8v I was measuring - and the fact that if you left it all unplugged
long enough it crept up to 12v.

suggestions to others with problems on this circuit:
-with key off, measure voltage to the heater blower relay (coil side) - will
probably be 12v.
-remove all other relays and fuses and re-check. If it is now zero, reinstall
one-by-one and then trace the circuit that pops it back up to 12v. There will be
a short there somewhere.
-if it is still 12v, remove the AC relays behind the glove box and measure
again.
-if it is still12v, remove all three power connections to the relay board
(position H in my car). two should have 12v and one should only have 12v when
the key is switched.
-if the switched one has 12v, there is a short between the ignition switch and
the relay board on the switched cable.

lastly, download and print the elec. diagrams offered on Pelican's site (they are more accurate and easier to follow than the Haynes ones). However they are missing a few areas and must be compared to the Haynes diagrams.

Paul