View Single Post
Old 19th August 2019, 08:06   #4
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by agw_01 View Post
I did notice that one of the wires was a different colour, blue on the 2 speed rather than blue/red on the 3.
Quote:
Is this a petrol fan, from a 1.8T perhaps?
Hi Andrew,

What are the markings on the control box lid? A diesel 3 speed should be 'M47' and a diesel 2 speed 'PWM2'.

The diesel fans do not have a connection to the blue wire on the car's loom.

The blue/red wire is essential on all fans. On the diesel it carries the PWM control signal so without it, your motor will not run.

Quote:
Once all connected up, I tried to run the fan by turning off ECON mode on the AC ..
To test the fan, turn on the ignition and press the windscreen demist button.
Quote:
... could someone please confirm whether directly replacing a 3 speed fan with a 2 speed fan and their matching relay boxes should be a direct plug and play replacement?
Yes it should.
Quote:
The pins used on the car's loom are the same and all low/high speed switching is done in the relay box?
Yes.

Andrew, you have an alternative solution. Renew the worn brushes in your 3 speed motor for £22 (check the commutator condition first).

I hope this helps but if you have any further questions please come back to me.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote