E39 540 - help with air con - drivers side!

[E1DJH]

The aircon sytem, which i run all the time, has suddendly stopped working on the driver's side, and blows very hot air.

The passenger side works just fine.

So, is it possible that a hose has become disconnected or something similar.
If so, can you suggest where i should start looking (can you tell i'm not very good with these things ? )

Many thanks for your help

[B'stard Child]

E1DJH said:

The aircon sytem, which i run all the time, has suddendly stopped working on the driver's side, and blows very hot air.

The passenger side works just fine.

So, is it possible that a hose has become disconnected or something similar.
If so, can you suggest where i should start looking (can you tell i'm not very good with these things ? )

Many thanks for your help

Sounds like a heater valve failure

Copied from another forum

Well as covered elsewhere the blackbird developed a couple of faults recently one of which was chuffing annoying as it was no heat to the drivers side of the car (worked fine on the passenger side)

A few searches pointed to the heater control valve assembly and it's not uncommon for them to go at 100K mark so I bought a new one having rulled out looking for a second hand one or trying to take the one i have apart to fix it and finding that I can't. If it can be fixed it can sit on the shelf just in case

So heater control assembly purchased and a few other bits



engine cover off



Think I found the cause of my slight water loss



I didn't undo that jubilee clip

Anyway solve that little issue later meantime

Old one



It was a little bit sludged up



other side



It's not a nice job to be honest but I've known worse!

I had heard that people have had some success with repairing these things

So I took it apart

Plastic casing (lots of crusty build up)



Motor unit (this was fine)



Valves



Seals were shot to bits and water had been getting into the valve motor



Move the spindle in and out and horrid gritty water came out



Valve seats pitted and chipped



Past repair and I think a new one was the right choice for me

[E1DJH]

B'stard Child said:

Sounds like a heater valve failure and some helpful stuff

Many thanks for that BC. It seems that this was resolving a "no heat" problem, and mine is a "too much heat, no cool air" problem, this looks like it will be a good place to start.

Anyone else got advice please?

[SJobson]

There are temperature sensors behind the little grilles in the centre console, one for each side. I could imagine that if the driver's side stops working but the passenger's works OK, it'd have the effect you describe.

[E1DJH]

SJobson said:

There are temperature sensors behind the little grilles in the centre console, one for each side. I could imagine that if the driver's side stops working but the passenger's works OK, it'd have the effect you describe.

Thanks for that, i'll have a poke around in the morning.
Do you happen to know if these sensors are easy to get to?

[B'stard Child]

E1DJH said:

B'stard Child said:

Sounds like a heater valve failure and some helpful stuff

Many thanks for that BC. It seems that this was resolving a "no heat" problem, and mine is a "too much heat, no cool air" problem, this looks like it will be a good place to start.

Anyone else got advice please?

Only that it's a whole heap more accessable on a 540!!!!

And I have heard that the valve can be jammed fully open or closed so full heat or no heats are both possibilities

You should be able to feel the temp of the pipes in the engine bay on a 540 and that will confirm heater valve seizure

[E1DJH]

Well, thanks to the help here i removed the heater control valve assembly chappie, and took it apart.
The two smaller cylinders, mounted vetically, seemd to be in perfect condition. Nice and shiney, with plenty of movement.

When i took the bottom, horizontal cylinder apart, i found a black plastic impeller (BC you refer to this as teh motor unit) which on first sight seemed ok. Then i found three bits of flat plastic floating around, and discovered that these were blades that had snapped off the impeller ( i couldn't find the fourth one).

So, it seems as if this is broken, so i hope it is the extent of the problem.
Does anyone know if i can get a replacement impeller, or do i need a complete unit; and either way, where do i get one from?

The other problem is why did these snap. Something must have got in there! What, how, and how do i know where it is now?

Many thanks again

[B'stard Child]

E1DJH said:

Well, thanks to the help here i removed the heater control valve assembly chappie, and took it apart.
The two smaller cylinders, mounted vetically, seemd to be in perfect condition. Nice and shiney, with plenty of movement.

Thats a good sign - doesn't mean the stepper motor on one side has failed but it's certainly good news if they are in good condition.

E1DJH said:

When i took the bottom, horizontal cylinder apart, i found a black plastic impeller (BC you refer to this as teh motor unit) which on first sight seemed ok. Then i found three bits of flat plastic floating around, and discovered that these were blades that had snapped off the impeller ( i couldn't find the fourth one).

So, it seems as if this is broken, so i hope it is the extent of the problem.

If the impellor blades are damaged and the pump is not working as effectively as it should then I believe that the symptoms would be lack of heat on both sides at low RPM's - the pump is in the system to boost the coolant flow around the heater unit at low rpms

It's a fairly simple system

Temp controllers in the car adjust temp based on temp sensors placed in the airflow on each side of the car - this feedback loop adjusts the water flow to the heater matrix(s) split one side driver other side passenger. And the cycle continues

Full heat on one side means either the water control valve for that side is fully open and not working or the controller system is getting wrong information from the dash setting or from the temp sensor in the airflow

E1DJH said:

Does anyone know if i can get a replacement impeller, or do i need a complete unit; and either way, where do i get one from?

Only avaliable as a complete unit motor and valve assembly - BMW dealer or Real OEM

E1DJH said:

The other problem is why did these snap. Something must have got in there! What, how, and how do i know where it is now?

Many thanks again

I would guess age and heat cycles may be a cause of failure but impact is possibility

[E1DJH]

Many thanks BC.

I'll get a new unit, and see what happens from there.

[E1DJH]

New unit purchased from BMW (they called it a water valve) - £150
Fitted last night, which was surprisingly easy really for a non-mechanic such as me.
Short test seemed to indicate problem is gone, so have a 300 mile round trip today to test the little blighter.

[B'stard Child]

E1DJH said:

New unit purchased from BMW (they called it a water valve) - £150

I forgot to warn you they aren't exactly cheap - £150 is a good price did you get some discount?

E1DJH said:

Fitted last night, which was surprisingly easy really for a non-mechanic such as me.

It's a lot hard when its at the back of the engine and not at the side like it is on a 5

E1DJH said:

Short test seemed to indicate problem is gone, so have a 300 mile round trip today to test the little blighter.

Phew - can I have your old one

[E1DJH]

Hi BC.

I paid list price from BMW. It seemed a bit steep to me, as i only really needed the impellor, but then i considered how much i have saved by you diagnosing the fault rather than them, and for me fitting it. I've just got back from a round trip down to Somerset, and all seems well, which is nice.

I rang the local dealer, Coopers in reading at about 11:00 am yesterday morning. Said they could get it delivered in to them yesterday afternoon, so i went for it.

In recognition of the help you have given, i would be delighted for you to have the old one , although i thought you had got yourself sorted? If you want it, i'm in Berkshire -where are you?

Are you planning to go to the PH Sunday Service next week end?

[B'stard Child]

E1DJH said:

Hi BC.

I paid list price from BMW. It seemed a bit steep to me, as i only really needed the impellor, but then i considered how much i have saved by you diagnosing the fault rather than them, and for me fitting it. I've just got back from a round trip down to Somerset, and all seems well, which is nice.

I rang the local dealer, Coopers in reading at about 11:00 am yesterday morning. Said they could get it delivered in to them yesterday afternoon, so i went for it.

Well that was good service - I had to wait a week for mine it's a common fault for the motor or solenoids to fail but they didn't have one in stock at my local dealer

E1DJH said:

In recognition of the help you have given, i would be delighted for you to have the old one , although i thought you had got yourself sorted? If you want it, i'm in Berkshire - where are you?

Norfolk but I'd be happy to pay for postage

I have got a brand new one on mine but I'll be honest with you I'd like to test the solenoids on yours - I don't think the pump failing could cause your symptoms - I have a good pump from my old unit and had I thought that would fix your problem I would have sent it to you

I'm just a curious chap and whilst I am happy as I can be that your fault is cured I'd like to find the root cause - I'm a die hard DIY'r and my experience is limited with 5' and 7's cos I've only had my 7 for a year but I've already done most jobs that are required on a car that has done 100K like transmission fluid and filter change as well as spark plugs and rocker cover gaskets and documented all the work with pictures on another forum - I like to share

[E1DJH]

If you PM me your address, i'll be happy to post it over to you.
If you stick the impellor from your old unit into this one, you should have a good spare.

My car, well it is wife's actually, has only done 63k miles, so it seems a little early for this to fail. Looking at the impellor, i can't understand how the damage ocurred, but i'll keep my fingers crossed that it doesn't happen again. If it does, i will recognise the symptoms,and will have the whole system drained to see if anything floats out.

Thanks again for your inyterest and your help.
Cheers, David

[Lieta]

I have the same problem like E1DJH. How to check the water valve once it is removed?

[JFT520]

Comments: The valve is a solenoid which when not powered is by default OPEN. Therefore, if you have no heat in the cabin, try unplugging the power to the valve. If this restores heat to the cabin then you have a control issue i.e. the valve is being told to stay shut by the ECU - most likely cause is the cabin temperature sensor. If unplugging it makes no difference then it is likely that the valve is seized shut.