Heater (or lack of) problem

[Gad-Westy]

I used my recently acquired E46 330 for it's first long journey over the weekend. It seems I have a problem with the heater. On short journeys, it seems to be working ok but on longer journeys it seems to go through long spells of only blowing cold air in. This happens in both auto and manual modes regardless of the temperature that is dialed in.

The engine temp looks fine so I don't think this is a thermostat problem. A quick trawl around google seems to suggest this may be a problem with the Heater Control Valve but I want some reassurance before shelling out for a new one.

Any basic checks I can do?

What's involved in replacing the Heater Control Valve if that is my issue?

Edited by Gad-Westy on Sunday 7th November 21:23

[Red&WhiteMonkey]

Could be the final stage resistor, commonly called "The Hedgehog". Have a look at http://www.motormec.co.uk/aircon.html and http://www.motormec.co.uk/aircon.pdf.

[Gad-Westy]

[quote=Red&WhiteMonkey]Could be the final stage resistor, commonly called "The Hedgehog". Have a look at http://www.motormec.co.uk/aircon.html and http://www.motormec.co.uk/aircon.pdf.
[/quote]

Cheers, I was under the impression that "the hedgehog" just controlled the fan. Is this not the case?

[Red&WhiteMonkey]

I'm not an expert on the matter but I think its all connected and a faulty hedgehog can confuse the whole heating system. A replacement part isn't too expensive and it is possible to change it yourself (although its fiddly and you'll probably lose some skin on your hands!), so I think its worth a try.

[phelix]

Symptoms of a faulty FSR are a heater fan that isn't doing what the display says. Pretty easy to check out - just turn the fan all the way up and then all the way down and see if the airflow changes to suit.

The thumbwheel on the dash centre vent controls the temp of air coming out of the dash vents - BMW's philosophy is to give you the option of cool fresh air on your face and warm air in the footwells to keep you warm *and* awake. If that wheel is set to blue you will only ever get cool air out of the centre vents; the system will modulate the heat out of the footwell vents in order to achieve the requested temp.

[Gad-Westy]

Cheers, fan works just fine. Should have said, centre vent is turned up to max heat, but all vents blowing in cold air regardless of temp set on control.

[Fox-]

I dont think this is the hedgehog. I think its something wrong with the cooling system. Check your coolant level.

[Gad-Westy]

Fox- said:

I dont think this is the hedgehog. I think its something wrong with the cooling system. Check your coolant level.

Yeah, pretty much ruled out hedgehog as fan working normally. Coolant level fine and I've tried bleeding any air out of it. The engine temp is rock steady so it seems that there isn't a thermostat issue. I'm almost sure it can only be one of only a couple of things (the other being a blocked heater matrix) but the intermittent nature of the problems makes me most suspicious of the control valve. Just want to seek verification before splashing out £100 on a new valve.