Cold Air blows above 50mph
 

12 months ago I bought my first X5 2004 4.4i. 112,000 miles. Being a massive fan of the V8 I decided I would get her back to as good condition as I could. I've spent a small fortune (twice what I paid for the car which was £3500)(I know, don't go there - could have bought a much newer one!)

There are still some issues but the most immediate one is a heating one. I run the car with aircon on pretty much all the time - hot or cold weather. A couple of months ago I noticed on a cooler day there was no heating available. I took it to the garage and with some investigation they found a small water pump leak but also changed the heater control valve (only available from BMW and costing £200!) which regulated heating getting inside the car. They also replaced the thermostat.

Since then - heat is available and lots of it but only around town at slow speeds.

If I go above 50mpg for most that 5 mins or so the heating goes cold. If I stop or slow down to 20mph - it comes back on. Fan continues fine - it's just the temperature of the heating.

Its a local garage and not a BMW dealer I go to - I tried BMW when I bought it and they spent £4000 for me and took 9 weeks in their very posh garage (it only went in for a service.).

This cant be a unique problem - can someone tell me what the problem is from these facts please?

Assuming you have the IHKA (automatic climate control panel)...without knowing how you have things set...it could be something simple or something complicated.

The IHKA has a lot of different settings that can manipulate air temp from the 3 major locations (windshield/face vents/floor vents). How do you have the control panel set? Is it on AUTO...or have you removed it from auto to manual selection of air direction...as well as...do you have the air speed on AUTO...or do you have it set on manual operation?

There's also the stratified air dial (the rotary dial in the center of the middle dash vent)...how do you have that dial set? If it is in the "blue"...then only cool/cooler air will blow from the face/dash vents regardless of the temp you have set.

If you take the system out of AUTO air distribution and select one of the choices (floor/face/windshield)...what happens then? Does the same thing occur where the air temp blows cold when you drive faster?


Stratified air dial can temper the air from the face/dash vent warmer/cooler based on how the dial is set. This allows you to blow cool air on the driver's face on a long journey (to stay alert) while the passengers can remain warm and toasty:

Hello - thanks for that - yes all of those settings work ok - but all only at low speed. And all of them used to work a faster speeds too.

In general I keep it off auto as I don't like a load of fan noise - so it's generally on a manual setting - floor and screen. Ive tried changing all the settings on various longer trips - end up with the same outcome. More than 5 min above 50 or so MPH - heating blows cool.

Its had recently a new waterpump, caps, thermostats, heater valve. The engine temp remains completely static and it warms up nicely. It's never overheated since I bought it August 2017.

What would be your more complicated things to look at!? :-)

Someone recently had one of the Bowden cables that operates the flaps for stratified air pop off - that caused a similar issue - cold(ish) air no matter the setting. :dunno:

Sorry - yes forgot to add - when the wheel control is on blue at low speeds - only cold air comes through. But when above 50mph - even on full hot - only cold air comes through.

Definitely points to a bowden cable coming loose. There is a bowden attached between the wheel and the flap.

If it was the cables - I don’t understand why I still get hot air at low speeds?

Without the cable holding the flap valve, the incoming air pressure at high speeds closes the flap and directs cold air out the vent. At low speeds the incoming air pressure isn't enough to overcome the air from the blower and the flap valve stays in the warm position.

Or it may be the other way around, with the high speed air creating a venturi effect on the duct and sucking the flap valve closed. Not sure which way the flap goes to switch between hot and cold (never had it apart).

That's my theory anyway... :dunno:

Check your coolant level. If it's getting low you will experience what you have. The electrical valve inline on the heater hoses can degrade and partially block the flow. Its on the US drivers side near the master cylinder.

I have this exact problem too. My coolant levels are fine. Google and a search didn't turn up much for bowden cable heat issues.