E38 1994 Heating issue, 740i standard

Hi all I'm getting towards my wits end over my heater.
I've read loads of posts etc
I have changed the aux heating valve and pump, then bled the system a number of times and after doing so have heat it's not hot but warm, the next day such as today I started up and it gave me medium heat for the first 20 minutes and then slowly got colder, I noticed that the centre vents that while the drivers was medium warm the passengers was cold and it does not matter where the controls are set it's the same, there is also an audible clicking sound coming from what seems to be from the passenger side bulkhead area, this can be quite regular at times, any ideas ???

The engine is running at normal temperature and whatever revs the car is at does not seem to make any difference, the other day I had hot air coming through to the rear and the car was warm which was nice ! Now it's minus 3 it goes cold again.

These cars can be tricky to bleed sometimes. I would make sure that there was no air in the system first by trying to bleed it a few more times. You should also try going out and really pushing that motor for a few minutes (safely) to dislodge whatever air may still be in the system.

If bleeding the system does not work, then I'd be looking at the blend door under the dash that switches from cold to hot air. But most of the time, it is just air in the system that causes cold air to come out of the vents.

My wifes 02 Jeep Grand Cherokee did this on her dual climate zone and it turned out to be a cheap plastic piece on the blend door. Whole dash had to come out. Then it would'nt give any heat after repair. This was cause by a resistor around the fan motor area in passenger floorboard. I smacked it with my hand and it works fine! Then the heat exchanger went out.....so on and so on. Not sure what the blend doors are made of on BMW's but Jeeps are junk. My 98 740i has not had this issue, but maybe the Jeep story helps?

Thanks for the replys I'm off tomorrow so going to do some trying around!
I'll let you know how I get on.

Well I've been cracking the cap and took her up some steepish hills today and on auto she seems to be giving me some warmth!
The test will be in the morning when I start and go to the dentists see if she still keeps blowing warm, it's not as warm as you'd expect but a drastic improvement, think I'll just keep doing the same and see if she comes hot.

Thankyou for your replys they are greatly appreciated, daren.

Check out www.E38.org for the bleeding procedure, and after a few times, enough air should be out of the system to cause heat to come out of the vents. You should bleed the system with the heat on full blast (front windshield defrost), and the front of the car on an incline.

Hi just wanted to say thankyou for your tips and it is now resolved!

I sat it with the nose up high running and since keep cracking the cap until the air sound stops and I have a heater!
I still have it set on high running around and it gets hotter and hotter, I've also run the air con today to make sure I don't get the oposite in the summer, thankyou all so much.

No problem, just remember that as the air comes out of the cooling system, the coolant level will get lower and lower. You should check the coolant level periodically to make sure that the expansion tank with the coolant is full.