Heater Control Fault

Sounds like a transistor to me.

I reckon if you stop driving into things you may affect the longevity of parts of your misunderstood vehicle.

Hello everyone - this is my first post!

I just acquired my first XM (details in signature) and have no heating / fan as discussed in this thread. The car does not have A/C - it has the "Auto, 0, 1, 2, 3, 4" fan control and 2 other dials.

I've removed Fuse 2 as described and replaced it (it did look slightly corroded at the contacts). But I still have no fan / heating.

Question:
Should I take the fuse box off (it's bolted to the air filter housing)? Will this help me clean inside and find wire connections? It looks like it might be a fiddle to get it off so I thought I'd ask bfore I started!

Thanks if you can help - and thanks for a great forum and site (much nicer to have forum then the Y! XM-L list which is SO hard to search).

Tom

If the fuse is OK and showing no signs of corrosion the most likely problem is the regulator transistors on the blower motor itself. Check and see if you have 12 volts on the thick red and black wires connected to the motor unit, if you do, the transistors are probably u/s.

You should find instructions for changing them on the forum somewhere, if you cant, just shout.

Peter.N.

Thanks for your reply Peter (and the other replies too).

I've found Noz's heater pdf - looks like fun! But first - very naive question: where are the red and black wires you speak of? (I need to get a manual soon!)

Also, my original question still stands - should I be detatching the fuesbox under the bonnet to look for loose connectors?

Thanks, Tom.

Check for a supply on the blower before you do anything else. The motor assembly is fairly easy to remove. Take of the cover under the glove box and you will see it. You will find a thick red and black wire connected by a plug, check the voltage across these leads. You really need to have a load on the supply as a high resistance in the circuit will still give you 12v which will dissapear when you load it.

Ideally you need the fan in operating mode when you check the voltage, but note that switching the ingition on is not sufficient, the engine needs to be running. Alternativly, check it with a 12v bulb with a couple of wires soldered to it, if the bulb lights normally that will establish the integrity of the supply.

To remove the motor assembly, remove the electrical plug/s and then the three screws that go upwards through the unit and the motor assy should drop out, with maybe a little assistance.

Peter.N.

This post has been edited by Peter.N. on May 22, 2006 10:05 pm

Thanks for the directions Peter. I've just had a chance to test things out.

I got the blower out and did the following tests:

1. Engine on, fan switch on. Test the 4wire brown connector with voltmeter. (Tested thick red and thick black connectors.) I get 12V.

2. Engine on, fan switch on - test across red + black single connectors (as described by XMExclusive on the previous page). I get no volts.

I wasn't able to try the test XMExclusive suggests of trying to run the blower from a 12V supply direct as my spare battery is flat.

I suspect from the above that it is transistors?

My girlfriend is borrowing the car for a few days so I won't be able to do any more tests until next Tuesday, but if anyone has any thoughts on this I'd be grateful.

Perhaps I should just get a whole blower from someone who's breaking an XM as I need some other bits too.

Thanks again for your help.

This post has been edited by knitatoms on May 24, 2006 09:01 pm

"My girlfriend is borrowing the car for a few days so I won't be able to do any more tests until next Tuesday, but if anyone has any thoughts on this I'd be grateful.

Perhaps I should just get a whole blower from someone who's breaking an XM as I need some other bits too."

Noz has issued repair details for the transistors on this site. See records. Small PCB (transistor) control unit incorporated in fan unit is Citroen supply at about £49. Whole fan unit is listed by M & C Lockwood (01274 640590) at £138 excl. VAT ,p & p. Also lists small PCB unit at £39.50 excl.

Hi

The fan assembly is I believe the same as fitted to Xantia or Pug 406. Scrap yards over here charge about £20 for one. I have found that it easier to stick in a spare fan and then repair the removed one to keep as a spare.

Regards

XMexc

Thanks for this I had a completely inoperative aircon/heater/blower and it was a corroded fuse box as stated. Saved a lot of time and effort!