Cold air blower question

[Buffoon]

Has anyone managed to access the cold air blower wiring connections, without removing pedal box first?

Spent far too much time trying to sort out the blower, when I can just open a window.

The problem is the blower is not working. The Heater Control ECU is fine. Without engine running and ignition on, the hot speed connector on the ECU is between 1.1 and 4v when running (to good earth). The cold speed connection is 2.8 to 9.5v and does not run. I'm assuming this would drop to same values if it were running, or there is something amiss with the switch unit. Was hoping to ground the blower return to test it, but looks like a demolition job to achieve it.

[CerbWill]

The connection to the fan is under the dash towards the driver's door, around where the a/c thermostat is.

Apologies if this insults your intelligence but it might be useful. The heater ECU controls fan speed with low-side PWM, so it switches the earth on & off at a high frequency with the ratio of off to on dictating the fan speed. The fans are fed with 12v ignition live. There's also some adjustment potentiometers on the back of the fan/air con control panel but they're unlikely to be the cause of a totally non-running fan I'd have thought.

Edited by CerbWill on Thursday 30th January 19:14

Edited by CerbWill on Thursday 30th January 19:16

[Buffoon]

Many thanks.

In my dark and distant memory, I think I may have been into that connector before. Could have saved myself a lot of time if my memory were still young and less pickled.

Problem was indeed a high resistance at connector. Thoroughly cleaned up now and working a treat.

[gruffalo]

CerbWill said:

The connection to the fan is under the dash towards the driver's door, around where the a/c thermostat is.

Apologies if this insults your intelligence but it might be useful. The heater ECU controls fan speed with low-side PWM, so it switches the earth on & off at a high frequency with the ratio of off to on dictating the) fan speed. The fans are fed with 12v ignition live. There's also some adjustment potentiometers on the back of the fan/air con control panel but they're unlikely to be the cause of a totally non-running fan I'd have thought.

Edited by CerbWill on Thursday 30th January 19:14

Edited by CerbWill on Thursday 30th January 19:16

These pots on the back of the board?

My hot fan is pathetic and that is me being very kind, almost pointless wouldbe more accurate. Would these pots be of any help?

[notaping]

My hot fan got progressively slower until it blew the power transistors in the control unit. Turned out to be gunked up bearings on the fan motor which go rusty from damp air coming into the hot box.

From recollection the fan comes out with the cover board in the passenger footwell, and the bearing are a couple of pounds for skateboard truck bearings.

[CerbWill]

gruffalo said:

These pots on the back of the board?

My hot fan is pathetic and that is me being very kind, almost pointless wouldbe more accurate. Would these pots be of any help?

They could be. If you remove the control panel from the dashboard there should be enough slack on the ribbon cable to leave it connected and turn the hot fan to full whilst you adjust the potentiometer with a small screwdriver to see what effect it has. At least it rules that out before getting to the heater fan itself.

[gruffalo]

Thanks guys, I will try both.

I will check the bearings first as I don't want to run the rick of burning the control unit out.