M52 problem heating fan (sometimes..)

Post Tue Dec 10, 2013 7:31 am

My m52 runs for a couple of weeks, didn't drive that far yet untill yesterday when I went for the MOT.
The heating fan always worked, while venting the coolant system it worked while the engine ran, but when the mechanic tested it, it didn't work.
When I started the engine after he was finished, the fan worked again... Turned the engine off, started and no fan.
I don't get it, anyone got an idea?

Post Tue Dec 10, 2013 9:12 am

Do you mean cooling fan?

Post Tue Dec 10, 2013 10:24 am

No, the interior blower.

Post Tue Dec 10, 2013 2:39 pm

When its not working, try the mirrors, if they dont work it could be unloader relay problems.
What was the previous engine, and is it a pre or post facelift car?

Post Tue Dec 10, 2013 4:32 pm

It's a post facelift, original m40, then I dropped in a M42 and now the m52.
Rear view mirrors don't work either when the blower refuses to work. I'm going to switch the relais, maybe it's an easy fix(in my case it's useally not).
What happens if pin 15 is not connected? The blower isn't turned off while cranking, or doesn't work at all?

Post Tue Dec 10, 2013 7:23 pm

You need to earth the wire (Black/Green Pin 15) to make the circuits work, its probably just a bad connection, most likely at the starter

Post Tue Dec 10, 2013 7:25 pm

Need to know if the electric windows are also included in the list of non working bits before any diagnosis can be made.

Post Tue Dec 10, 2013 8:56 pm

I have electric windows, but they have their own supply.
Pin 15 is connected, just want to make sure that the blower stays in 'off' if the connection is faulty, so I don't have to open the loom just yet.

Post Mon Dec 16, 2013 4:26 pm

Changed the relay, so far so good.
New item; sometimes the engine quits on me, after slowing down till stopping. Fires right up after this.
The engine didn't run for about 2 years, I renewed all the hoses.
Idle is ok, runs a bit rough till 2500 rpm, after that it's fine.
I think the fuelpump can be the problem, lack off pressure/duty.
Other options?

Post Mon Dec 16, 2013 4:33 pm

Speed signal to ECU will be missing

Post Mon Dec 16, 2013 4:57 pm

But then it should be a problem everytime, it only happens 1 out of 10 or less(?)
I did wire the speedsignal, shouldn't be a problem. I'll check it anyway this week.