Heater fan operation, troubleshooting Options

[malcolm2]

The only thing installed on my car that is associated with HEAT would be the exchangers. Nothing else. I need to get the heat working so I started with the Heater fan in the engine bay.

SO FAR:
successfully bench tested the fan with 12v.
Put a known good headlight relay in the fan relay socket
Successfully checked continuity of the wire from the lever to the 14-pin connector (GRN/wht). Connector attatched, and unattached
Successfully checked continuity from the relay (87) to the fan (green wire), car was not running.

Strange thing I noticed. Checking continuity from the lever to Pin #9 was good. I then checked continuity between the lever and pin 13, 11, 7, 5, 3, 2 & 1. With the 14-pin connector connected they all showed continuity to ground. THIS CAN"T BE RIGHT, can it? The car runs fine, all the lights work. Seems like a ground short, but it is not affecting anything else.

My goal here was to (as designed) get 12v to the green wire on the fan, but I can't. I have read several posts that gave me some direction. But I am lost.


Thanks,

Clark

[Dave_Darling]

Correct, the switch on the DEFROST lever grounds pin 86 on of the blower relay. Pin 85 of the relay has "switched power", and is hot when the ignition is on.

When 86 is grounded, the relay connects #30 to the "output", 87. Pin 30 gets its power from the rear-most fuse on the relay board.

The relay is just a switch. If you put a jumper wire between 30 and 87 on the relay socket, you are doing the same thing that the relay would when it was triggered (through 85/86).

That's one way to temporarily test; put a jumper wire there and see if the blower runs. If not, check the fuse on the relay board.

If it does run, then make sure that pin 85 on the relay socket has power when the key is on. Also make sure that 86 gets grounded when the lever is up.

--DD