CDTI cooling fan

bsafly · 8th June 2021, 14:18

I recently had a new fan fitted to my 2003 75 tourer (to replace the three speed fan of which no speeds worked) so I could get the air conditioning up and running which has never worked all the time I've owned the car.
Had a full air con service and re-gas today, they gave the system a thorough going over and no found faults or detectable leaks (the company I used are air conditioning specialists with good reputation who i have previously used for a regas and service on my ZT-T 190 two years ago and that is still working well).
The journey home was lovely with nice cold air and the ATC doing its job well, however when I arrived home and got out of the car to open the gate the cooling fan was extremely noisy which seemed odd as I had done the demist test after the new fan was fitted and it operated nice and quietly. A quick inspection through the grille showed no debris etc caught in the fan
I parked the car up, turned it off and left it whilst I had a coffee, on returning to the car carried out the demist test - the fan was running nice and quietly as expected, however as soon as the auto button is activated on the ATC control the cooling fan ramps up to high speed and runs at that until the air con is turned off.
Does anyone have any ideas as to the reason this happens, my thinking at the moment would be incorrect wiring of the new fan or trinary switch fault, suggestions gratefully accepted.
Many thanks, Paul.

8th June 2021, 14:18	#1
bsafly Just going about! Rover 75 CDTi Connie SE Tourer starlight silver and serpents. MG ZT-T 190+ in Raven Black. Join Date: Mar 2016 Location: Great Leighs Posts: 471 Thanks: 626 Thanked 167 Times in 110 Posts	CDTI cooling fan I recently had a new fan fitted to my 2003 75 tourer (to replace the three speed fan of which no speeds worked) so I could get the air conditioning up and running which has never worked all the time I've owned the car. Had a full air con service and re-gas today, they gave the system a thorough going over and no found faults or detectable leaks (the company I used are air conditioning specialists with good reputation who i have previously used for a regas and service on my ZT-T 190 two years ago and that is still working well). The journey home was lovely with nice cold air and the ATC doing its job well, however when I arrived home and got out of the car to open the gate the cooling fan was extremely noisy which seemed odd as I had done the demist test after the new fan was fitted and it operated nice and quietly. A quick inspection through the grille showed no debris etc caught in the fan I parked the car up, turned it off and left it whilst I had a coffee, on returning to the car carried out the demist test - the fan was running nice and quietly as expected, however as soon as the auto button is activated on the ATC control the cooling fan ramps up to high speed and runs at that until the air con is turned off. Does anyone have any ideas as to the reason this happens, my thinking at the moment would be incorrect wiring of the new fan or trinary switch fault, suggestions gratefully accepted. Many thanks, Paul.