Heater has stopped blowing

Hi guys, forgot my details so had to start a new profile. I too have the same issue with my heater blower. Happened one morning last year on the coldest morning of the year so that was just bliss.

So far i have checked the fig 40amp fuse, the resisitor pack has been replaced and did nothing, the heater control panel (switch type not 8 speed one) has been changed to see if its that but that did nothing.

I've read up what i can on here about the problem but then reached a part where the wiring from the control panel is apparently different on the diesels to the petrols so I was stuck at that point unsure what the wiring was from there.

The multiplug from the control panel does show a shorting burn mark on one of the contacts so i'll upload that pic if that helps. I've bought a replacement fuse box also as i'm aware from the other posts that it could be a relay built into the fuse board that could be to blame.

Thanks in anticipation of your replies guys and girls.

Yes please add photos by following the instructions in this topic - how to attach pictures .

Check fuse F18 in the BSM (the engine bay fuse box).
Power comes through that fuse to a relay in the BSM, relay might be shot. Should have +12 at pin 1 (and chassis ground) of fan plug when the car is running. If no volts problem is in the BSM. If 12 volts then the problem is in the controller or associated wiring.

Many thanks for prompt replies guys. When you say Pin 1 of the fan plug I assume this is the multi plug that is actually on the fan itself? I have not got to the fan yet. Heard its a bit of a mare to get to so was leaving that until i absolutely had to.

Ozvtr wrote: ↑Sun Jan 03, 2021 1:15 am Check fuse F18 in the BSM (the engine bay fuse box).
Power comes through that fuse to a relay in the BSM, relay might be shot. Should have +12 at pin 1 (and chassis ground) of fan plug when the car is running. If no volts problem is in the BSM. If 12 volts then the problem is in the controller or associated wiring.

Fuse 18 is complete and intact.

reddandanfireman wrote: ↑Mon Jan 04, 2021 9:34 am When you say Pin 1 of the fan plug I assume this is the multi plug that is actually on the fan itself?

Yes.

Another option is checking for +12V at the connector on the back of control panel. There should be a 15 pin double row connector, 'A' row and 'B' row. Pin A4 should have a big fat black wire in it. Between the metal contact in the wiring harness and ground, with the engine running there should be 12 Volts (or so). This point adds the fan to the measuring circuit but the fans appear to be pretty reliable. So this is measuring if you are getting power from the BSM.

Option 3? Remove the Green connector on the BSM and check for 12v with the engine running on pin 8. The wire in the green connector is pink but you are checking the pin in the BSM. The pin numbers are molded into the bottom of the receptical in the BSM.

The two main suspects are going to be the relay in the BSM or that damage that you mentioned to the connector on the back of the control panel. The fan draws a lot of power continuously and physical damage to connectors is not uncommon.

Option 4? Just replace the BSM? You said you bought a 'new' BSM? If you do this be careful of the nut and stud clamping the BSM to the bottom of the box...It's connected directly to battery positive! Either be careful not to short your tools to ground or remove the battery positive. The BSM is retained by molded clips around the edge, just take your time to find them all or the BSM wont come out.

Ozvtr wrote: ↑Mon Jan 04, 2021 11:25 pm

reddandanfireman wrote: ↑Mon Jan 04, 2021 9:34 am When you say Pin 1 of the fan plug I assume this is the multi plug that is actually on the fan itself?

Yes.

Another option is checking for +12V at the connector on the back of control panel. There should be a 15 pin double row connector, 'A' row and 'B' row. Pin A4 should have a big fat black wire in it. Between the metal contact in the wiring harness and ground, with the engine running there should be 12 Volts (or so). This point adds the fan to the measuring circuit but the fans appear to be pretty reliable. So this is measuring if you are getting power from the BSM.

Option 3? Remove the Green connector on the BSM and check for 12v with the engine running on pin 8. The wire in the green connector is pink but you are checking the pin in the BSM. The pin numbers are molded into the bottom of the receptical in the BSM.

The two main suspects are going to be the relay in the BSM or that damage that you mentioned to the connector on the back of the control panel. The fan draws a lot of power continuously and physical damage to connectors is not uncommon.

Option 4? Just replace the BSM? You said you bought a 'new' BSM? If you do this be careful of the nut and stud clamping the BSM to the bottom of the box...It's connected directly to battery positive! Either be careful not to short your tools to ground or remove the battery positive. The BSM is retained by molded clips around the edge, just take your time to find them all or the BSM wont come out.

Great thanks, thats very helpful. I did go through this last year when it happened but have forgotten what i did. I remember getting 90% of the way through removing the BSM inclipping the clips and finding it still stuck and lifting the fuse box itself as it went so I gave up. I later found a post saying about the clamping. How do you get the BSM out without causing damage when it is clamped like that? I'm still unsure of a correct removal procedure?

Thanks for the heads up on Option 2 I will try that method as the control panel is easily accessible. Will keep you updated.

Ok update, have removed the control panel and taken a reading from pin A4 on the multi plug. This is reading 8-9v so i assume my output from the BSI is ok?

The pics i posted show a burn mark on A6 and this is not reading any voltage at all. No idea if this is a power or earth cable so not sure if that means anything.

reddandanfireman wrote: ↑Tue Jan 05, 2021 11:46 am Ok update, have removed the control panel and taken a reading from pin A4 on the multi plug. This is reading 8-9v so i assume my output from the BSI is ok?

Not really. What is the terminal voltage of your battery? 8-9v shows high resistance in the circuit, assuming a terminal voltage of about 12V. The resistance of the fan is going to be very small and should not cause a voltage drop of that magnitude (3-4V).

reddandanfireman wrote: ↑Tue Jan 05, 2021 11:46 am The pics i posted show a burn mark on A6 and this is not reading any voltage at all. No idea if this is a power or earth cable so not sure if that means anything.

Your photos go to a dead link.
To attach photos to a new post click on the "Attachments" box just below the "post a reply" dialogue box (that you type your post in). You will see two tabs, Options and Attachments. Click on attachments, then "add files" then brows your computer for the pictures. Arfur added a link for the procedure above.
A6 is one of the earths for the panel, there are two. A6 is the earth for the fan return current I would say and that explains the melted/damaged connector. As I said the fan draws a lot of current over a long time and damage like this is not uncommon and might contribute to the fan not working. Melting shows heat build up from a poor electrical connection. The amount of heat generated is equivalent to the square of the current times the resistance of the joint (in "Watts"). As an example, a connection with a resistance of 1 Ohm that has a current flow of 2 Amps will produce heat equivalent to 4 watts (2 squared times 1). 5 Watts will cause a blister on your finger! At a guess the fan would be drawing between 5-10 Amps, so you can guess that the resistance of the joint doesn't have to get very high before a lot of heat will be generated!
You will see the clips around the perimeter of the "new" BSM. The BSM is a very neat fit in it's retaining box and getting all of the clips loose at the same time is difficult but keep trying.

Yes i just noticed the pictures post was disapproved. Strange as it had instructions on how to post links from website pic(google photos). Either way i'll post them direct. Ok so i assume from this the BSI is still suspected the culprit, is there a way i can test the fan for movement from one of the control pins to eliminate that also. The only reason I ask here is that from other threads the petrol multi plug to the control panel has different wiring and want to make sure i'm not probing the wrong pin or doing any damage. Thanks