trigger fan speeds

mincer · 15th June 2011, 17:58

i have found out that the slow speed on my v6 [with 3 speed cooling fan] does not work and i have not heard the fast speed for a few hot days so i am going to replace the motor brushes.
as i am replacing the timing belts, i am going to remove all of the front end and radiators to make the belt change a bit easier.
but as i will not be re gassing the ac straight away, i need to check that i have the 3 fan speeds.
as there is no gas in the ac, i dont think i can do the demist trick to trigger the low speed.
i have seen on here somewhere how to make the 3 speeds work but i cant find it.

SD1too · 15th June 2011, 18:14

Martin,

With a charged air conditioning system you can only operationally check the low and medium speeds of a 3 speed fan system.

As you are going to renew the faulty motor brushes why bother with the check? When you open the motor casing you will be able to see the condition of the fast speed brush.

Alternatively, as you are removing the front bumper, you can check all three speeds by separating the two fan motor connectors and linking the appropriate cables directly to the car battery.

Simon.

T-Cut · 15th June 2011, 18:15

You'll have to test it by increasing the coolant temperature. With the engine running, these are the fan trip points.

Low: On at 100C, off at 96C
Medium: On at 106C, off at 102C
High: On at 112C, off at 108C

When engine is stopped: High comes on at 115C (max. 10 mins.), off at 112C.

15th June 2011, 17:58	#1
mincer Regular poster rover 75 diesel tourer x 2. Join Date: Aug 2010 Location: southampton Posts: 48 Thanks: 0 Thanked 0 Times in 0 Posts	trigger fan speeds i have found out that the slow speed on my v6 [with 3 speed cooling fan] does not work and i have not heard the fast speed for a few hot days so i am going to replace the motor brushes. as i am replacing the timing belts, i am going to remove all of the front end and radiators to make the belt change a bit easier. but as i will not be re gassing the ac straight away, i need to check that i have the 3 fan speeds. as there is no gas in the ac, i dont think i can do the demist trick to trigger the low speed. i have seen on here somewhere how to make the 3 speeds work but i cant find it.

15th June 2011, 18:14	#2
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,382 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Martin, With a charged air conditioning system you can only operationally check the low and medium speeds of a 3 speed fan system. As you are going to renew the faulty motor brushes why bother with the check? When you open the motor casing you will be able to see the condition of the fast speed brush. Alternatively, as you are removing the front bumper, you can check all three speeds by separating the two fan motor connectors and linking the appropriate cables directly to the car battery. Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

15th June 2011, 18:15	#3
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	You'll have to test it by increasing the coolant temperature. With the engine running, these are the fan trip points. Low: On at 100C, off at 96C Medium: On at 106C, off at 102C High: On at 112C, off at 108C When engine is stopped: High comes on at 115C (max. 10 mins.), off at 112C.