Heater works in accesories mode, but not while car is running.

[jasonsnoddy]

So yeah. 1990 325is, m20 motor.

Heater and blower work fine before I start the car. Then when the car is running. Zilch, nada. Even the lights for the buttons down on tht panel don't come on (i.e. a/c, recirculating air).

Yup, searched.

Yup, checked fuses.

Possibilities?

[Holland]

Well... Haters gonna hate...

[jlevie]

Could be a problem with the unloader relays

[jasonsnoddy]

Ignition switch maybe? Swapped out relays and nothing is different. Also the windows do the same thing. Work in accessories, not while engine is on.

[b*saint]

Unloader relay related of course. I dont have the schematics but it sounds like something is not energizing the coil after starting, only before. And of course I mean the "A1 A2" terminals of the relay not your starting coil. Have you checked the schematic or were you banking on us?

[jasonsnoddy]

Spent a good half hour trying to get the bentleys charts and shit, just making sure there isn't anything glaringly obvious I'm missing. Which it looks like there isn't, I just gotta figure this shit out.

[mr walker]

The power windows and HVAC receive power from relays K5 and K7 respectively.

Could you check to see if there's anything else that doesn't work, such as the power door locks, lights, radio, etc.?

I'm not totally sold that this is a relay issue. I guess the question is: what's changing on the power distribution side of things when the engine is running vs. the key being in the run position?

[jasonsnoddy]

Everything else works as normal, and now the windows are back to normal. Weird as hell.

[Kershaw]

The power windows and HVAC receive power from relays K5 and K7 respectively.

jump the k5 and k7 unloader relays. just to see.

its very possible that this is ignition switch related as well.

[mr walker]

I'm thinking it could be ignition switch related (what else switches power before the relays??), but it seems really strange that a faulty switch would only be affecting 2 (or it looks like just 1 now) circuits...I would expect all or nothing.

But yeah, do what Kershaw said.

[KenC]

A bad ground on the starter will affect the windows and blower motor as well.

[jlevie]

I don't see this being a problem with the ignition switch. The Acc contact in the switch closes when in Acc and remains closed for Ign & Start. There is only one wire from the Acc contacts. With only the heater and/or windows affected the Acc circuits are hot, meaning it isn't the switch.

But the HVAC, windows, and mirrors are run through the unloader relays. If one of those relays is not working correctly the things it controls will be affected. Off hand I don't remember for certain where the unloader relays get power, but I think it is off the accessory circuit. The relay coils are grounded on early cars (up through 8/87) or grounded through the starter's unloader circuit on later cars.

While this could be a simple fault in the unloader relays or their wiring, if aftermarket electronics has been installed I'd look at that first.

[jasonsnoddy]

A bad ground on the starter will affect the windows and blower motor as well.

Well fuck, just looked at the starter and the smaller ground is in half. Now I owe you a handjob.

[Kershaw]

did it fix your problem?

[jasonsnoddy]

Well I'm at work right now, so I haven't had a chance to reconnect it. I'll update when necessary.