540i Heater not very warm

[Leigh2007]

Hi all just got my self a 540i 1996 auto (what a car :eek: ) but the heater is really only luke warm at best, the temp gauge is bang in the middle all the time, the left heater dial is broken and feels like its not connected to anything but the right seems ok (RHD car) but as I said the heat output is very poor at best, any one experienced this before? Any ideas what could be wrong? Surely at least the right side should produce reasonable heating.

(I live in UK so heat is required this time of year lol )

[chrisdaph]

Hi all just got my self a 540i 1996 auto (what a car :eek: ) but the heater is really only luke warm at best, the temp gauge is bang in the middle all the time, the left heater dial is broken and feels like its not connected to anything but the right seems ok (RHD car) but as I said the heat output is very poor at best, any one experienced this before? Any ideas what could be wrong? Surely at least the right side should produce reasonable heating.

(I live in UK so heat is required this time of year lol )

The cooling system might need to be bled and/or the heater control valves aren't functioning properly.

[m60power]

Check your heater valves, they could be stuck. Check them by applying 12 volts to each harness input and listen for them to actuate when you apply the voltage.

Check the aux water pump as the plastic impeller gets brittle over time and breaks off from the motor shaft.

Could also be your heater core, although probably not.

If its not the heater valves then its most likely one of the stepper motors broken off from their mounts. you can check this by feeling if there is heat from the floor or defrost but not the mid-level/center vents.

As mentioned before, also check to make sure the cooling system is properly bled. The 540s are self bleeding i think...

As for the dial, I'm pretty sure all the passenger temp dials are looser than the driver's side, mine is, and i have no idea why.

[sachmo12345]

Can you smell coolant with the heat on?

[tonyroc14]

Check your heater valves, they could be stuck. Check them by applying 12 volts to each harness input and listen for them to actuate when you apply the voltage.

Check the aux water pump as the plastic impeller gets brittle over time and breaks off from the motor shaft.

Could also be your heater core, although probably not.

If its not the heater valves then its most likely one of the stepper motors broken off from their mounts. you can check this by feeling if there is heat from the floor or defrost but not the mid-level/center vents.

As mentioned before, also check to make sure the cooling system is properly bled. The 540s are self bleeding i think...

As for the dial, I'm pretty sure all the passenger temp dials are looser than the driver's side, mine is, and i have no idea why.
plus one on everything. the 540 is self bleeding. Also the passanger dial is looser as it doesn't have the overide feature that the driver side dial does, i.e. all hot, or all cold

[Leigh2007]

Thanks guys, sachmo12345 no there is no coolant smell at all, now before I start pulling things apart is this the aux water pump and heater valves?
http://xs136.xs.to/xs136/09071/heater192.jpg

[chrisdaph]

This post and pictures may help you:

http://www.meeknet.co.uk/E38/E38_Heater_Valves.pdf

And so might this:

http://www.bimmerboard.com/forums/posts/59836/

[Leigh2007]

http://www.meeknet.co.uk/E38/E38_Heater_Valves.pdf
That says M67 only, sure mines M60, right?

http://www.bimmerboard.com/forums/posts/59836/
Can't find anything under bonnet that looks like that?

[raceyBMW]

Your heater control valve is going to be on the driver's side near the firewall. It has a plastic "shelf" on top you will need to remove to see the valve.
http://www.realoem.com/bmw/showparts.do?model=HK41&mospid=47398&btnr=64_0114&hg=64&fg=18

[sfgearhead]

Another quick and easy check is to replace your microfilter. Even if you're getting heat, without airflow you won't get much in the car.

Good luck!

[m60power]

Thanks guys, sachmo12345 no there is no coolant smell at all, now before I start pulling things apart is this the aux water pump and heater valves?
http://xs136.xs.to/xs136/09071/heater192.jpg



Yes, this is your heater valves and aux water pump.

[Leigh2007]

OK I put 12v across the valves (1) and I can hear a click either way, so I guess they are working, next I put 12v across the aux water pump (which I assume is the plug circled 2) and nothing, so if number 2 is the pump plug im guessing its that, right?
http://xs536.xs.to/xs536/09072/untitled1845.jpg

[Leigh2007]

OK got a second hand aux water pump for £10 fitted it now the heater is HOT :) thanks guys :)
Now........ the air flow is still poor even with the fan on full, checked the microfilter seems clean, kinda white/grey colour, any other filters that may be blocked?