1992 Series 3 XJ12 Blower does not work in Low & Mid position

[Ken Briffa]

I have encountered the following problem which my mechanic is finding difficult to solve. I need your help please.

My car is a Daimler Double Six XJ12 Series 3 from 1992, one of the last made.
The Air Con has had all engine bay hoses replaced with new. In addition the dryer and the compressor are also new.
The car produces plenty of cold air but only with the blower switch on High. Also in high & auto (temperature set) the blower does not switch off when the requested temperature is reached. On high the blower works fine in manual mode.

The blower does not work (turn on) on low or medium setting independently of whether in manual or auto mode.
Sometimes if the blower is set to off, the blower does turn on when put in low or medium, but if it does does, it works for a few seconds and then turns itself off.

Any ideas? What could be the problem.
I would seem to rule out the temperature sensor as the problem occurs in manual mode too.

Thanks all and best regards,

Ken

[mike020150]

It sounds as if the large heater/aircon relay may be at fault. Try substituting it with another unit. It can be found hiding behind the left hand 'cheek' trim piece alongside the heater and its controls. Mike.

[Ken Briffa]

Thanks Mike I will try that after having spoken with my mechanic.
Ken