Heater not working when the engine is running??

[thisismatuuu]

So im having yet another problem with my just swapped m50b25. Heater works just fine when the engine isnt running (all speeds work). But as soon as i start the car, the heater fan stops working. I can get the heater fan working 1 out of 10 times i start the car. Where should i start diagnosing the problem? Ground wires are new and i have ground straps on both side of the engine block.

[paultv]

I'm sure Brian will give a more detailed analysis but I wonder if your K7 unloader relay is sticking/faulty...I'm sure it feeds fuse 20 for the blower motor...obviously check the fuse and its seating as well.

Paul

[Brianmoooore]

This appears to be an E30 that has just be fitted with a different engine, complete with different starter motor, so the first thing to establish is whether the unloader relays are working at all.
Do the electric windows an electric sunroof work with the engine running/not running and doors closed?
Do the electric mirrors work with the engine running/not running?
What did you do with the black/green wire that went to the 8mm stud on the original starter motor?

[thisismatuuu]

my car has only electric mirrors which dont work, starter has 3 wires behind it, engine came from pre facelift e34 without vanos so the engine to body connector was the same. wipers work (barely) regardless wether the car runs or not.

[Brianmoooore]

What did you do with the black/green wire that went to the 8mm stud on the original starter motor?

[thisismatuuu]

it just got bolted to the 8mm stud it goes to, no idea where it leads to in the loom.

[Brianmoooore]

Is this on the M50 starter motor? Any chance of a close up pic of the motor solenoid area?

[thisismatuuu]

i can get a picture of the starter motor after work, right now im running the original m40b16 starter and flywheel.

[Brianmoooore]

engine came from pre facelift e34 without vanos so the engine to body connector was the same.

Early E34 525is that were fitted with the M20B25 came with a loom that was electrically similar to that on a six pot E30, but I've never heard of a M50B25 loom that was fitted with the E30 type C101 plug. All the M50 looms I've dealt with have had a 25 pin X20 plug on them. If such a loom exists, then I've learnt something today.
You need to disconnect the 8mm ring terminal from the starter solenoid, disconnect the engine loom plug from its socket next to the fusebox, and use a meter to check for electrical continuity between the 8mm ring and pin 15 of the C101.

[thisismatuuu]

swapped out the k7 relay, and tried it 15 times last night and everything seemed working.

[Brianmoooore]

How about the mirrors?