W124 heater dial problem

[MotardMan]

I noticed, or rather my wife noticed, that the temperature dial on the left of the heater cluster just goes round and round and round! It does not appear to be doing anything on its travels either, we just get permanant cold air. The dricvers side control works just fine.

Are the controls easy to remove and work on? Has anyone had any experience of this at all?

Best,

Jim

 

[andy_k]

they are easy enough to get at -

remove the facia by pulling the heater controls off, removing the two large retaining nuts and the 2 screws above the ashtray.

Then, the whole section with the switches in is fixed with 4 cross head screws, slide it out and disconnect the multi pin connector from behind.

The temperature switches have their travel limited by a sprung ball bearing (as far as I am aware) it sounds like this has popped out - possibly by over zealous use of the switch.

I'd suggest replacement would be the only option here. Something else to do whilst you are looking at that rear wiper switch

HTH

Andy

 

[MotardMan]

Hi Andy,

Cheers mate! :wink:

I'll take it out tonight and have a wee look at what has happened. I assume there is only an elctronic link to the heater matrix then, that must be what the wiring is for. Sorry dumb question.... :?

If I can get the thing to operate correctly, then maybe it is saveable? It seems to me that the electronic link, or rheostat that sends a signal to turn up the heat is not getting to the bits that actually do turn up the heat. Does this make sense?

Anyhow, I wonder, worth risking a second hand one?

Best,

Jim

 

[andy_k]

the multi pin wire connects all the electronics on that panel - heater fan etc. there's a printed circuit housed in there so that's a non serviceable part at a guess

the temp control may be salvageable but i'm guessing that without that little ball bearing to constrain movement it's been "forced" past the end of it's travel so the components of the rheostat will very probably be stuffed.

If you've got access to a second hand one then no harm in trying it. Most of the breakers offer a "warranty" on their parts - "mercman" gives 7 days and "the garage" gives 3 months as a rule.

in order to test

Each valve closes at +12V. Pins 1 & 2 take 12V from fusebox. Temp wheels at min give 0V on pin 3 (right) and pin 4 (left). You can test valve by:
- pins 1 & 2 to a known +12V (e.g. a fuse)
- pins 3 & 4 to a good earth

With engine warm and running, this should give ambient temp air through the heater. Best doing it with full blower and giving it it time to run cool.

this information was originally posted by Malcolm Brown on another heater related thread
Andy

 

[MotardMan]

Brilliant, a top bit of advice. I'll whip it out tonight and take a look. I need the part numbers B4 the Garage will sort me a price for the parts anyway.

Thanks again,

Jim

 

[andy_k]

this could be the answer to all your problems

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2416215788&category=10398

A wild guess would be that it's this unit that is at fault on your car - and that the heater/rear wiper problem may well be linked.

Happy bidding

Andy

 

[MotardMan]

this could be the answer to all your problems

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2416215788&category=10398

A wild guess would be that it's this unit that is at fault on your car - and that the heater/rear wiper problem may well be linked.

Happy bidding

Andy

Thanks Andy, but that unit is for a car with A/C, and mine just has the plain old fresh air cooling.... :lol:

I love eBay though. I could spend hours browsing......

Jim

 

[MotardMan]

Fixed!

I bought the spare heater control module from euromerc, it took a long time to arrive, but was worth the wait. It took me just 15 mins to fit the thing and test it. All working now!

Hurrah! I am happy, the SWMBO has stopped whinging, but has not thanked me yet :wink:

Jim