Cooling (radiator) fan not working, '05 ZT 190

[White horse]

Originally Posted by FrenchMike

dont' waste your time .there 99 out of 100 the motor itself is implied

You are no doubt right there, never the less it would be nice to know if the rest of the associated system is OK. As I said, reluctant to probe the system and risk damage elsewhere. I think one of Jules's fans will be ordered shortly!

[FrenchMike]

Originally Posted by White horse

You are no doubt right there, never the less it would be nice to know if the rest of the associated system is OK. As I said, reluctant to probe the system and risk damage elsewhere. I think one of Jules's fans will be ordered shortly!

I guess Jules now proposes the Revotec (two speeds)and he 'll give you all the wiring détails

[SD1too]

Hello John,

I'm impressed with your thorough approach. Perhaps I can assist a little. I renewed the brushes on my own 3 speed motor years ago.

The tests which you mention will only trigger the slow and medium speeds. Both these commonly fail when just one motor brush wears down to minimum. Fast speed cannot easily be tested.

What this means is that it's very likely that you have one or two worn motor brushes. These can be renewed inexpensively if you have the ability and the dedication. Just remove the motor, take off its end cap and have a look. You'll have to do this anyway if you choose to buy an expensive aftermarket motor, so why not allow yourself the opportunity of a much cheaper and long-lasting repair?

Have a look at Arctic's posts for very helpful photographs of what to expect.

Simon

[White horse]

Hi Simon

The fan is almost off the car now, so as you suggest I'll open up the motor and have a look at brush replacement. Anyone have a link to Arctic's post regarding brush replacement?

[Arctic]

Hi John.
If it turns out anything like this below the game is over I am afraid
1

2

3

4

5

Only the control box and PCB board were any good for future use from this fan

If they turn out to be like this fan below you are on to a winner for repairing

6

7

8

check and clean all parts etc
9

check magnets are ok and not cracked or loose
10

11

12


Brushes need replacing
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cut off the damaged brushes and solder on the new ones refit the motor back together
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16

17

Good luck

[White horse]

Thanks for the photo's, fan off tomorrow for a look.

[SD1too]

Excellent John. Be careful when gripping the motor body in the vice in order to release the end cap. The permanent magnets are composite and very brittle. They are also glued to the inside of the casing! Use the minimum necessary force.

Simon

[Jules]

If you don't want to go down the Revotec route I have many duff 3 speed motors available which will be good for spares.

I suggest you buy 2 motors in order to get enough good OEM brushes to rebuild your own or one of the motors you receive (if one turns out to be in better shape!)

£8 each plus £8 PP.
PP stays the same for up to 4 motors

[White horse]

Fan off the car, opened up the motor, guess what I found? Yes, badly worn brushes! Worse than those in Arctic's photo's.

Before removing the fan from the car I re-did the tests I did previously with a 12 volt battery, this time with a battery with some volts in it! The control box has 3 relays in it, 1 big, 2 small. With the big relay and the middle small relay the fan ran. The 2nd small relay, although clicking, failed to set the fan running. I'm hoping that that is the low speed relay.

The commutator looks well worn so at the moment I favour a new fan.

One final question, on doing the demist test, even if the fan does not run, should the relay in the control box click?

John

[SD1too]

Originally Posted by White horse

With the big relay and the middle small relay the fan ran.

That's the medium speed circuit but running at low speed because one of the brushes is no longer in contact with the commutator.

The 2nd small relay, although clicking, failed to set the fan running. I'm hoping that that is the low speed relay.

It's the high speed relay, and it will only increase the fan speed when the other two relays are energised.

The commutator looks well worn so at the moment I favour a new fan.

Really? It seems from your description that you only need one new brush! The commutator must be OK as the motor ran.
Why not carefully extract all the brushes from their holders to check the remaining length. Here's where to buy new ones. They're miles cheaper than a new fan! Scroll down to the grey panel on the left of your screen and click on the Rover 75 reference (ignore the 'heater' error).

... on doing the demist test, even if the fan does not run, should the relay in the control box click?

Yes.

Simon