The 75 and ZT Owners Club Forums - Cooling (radiator) fan not working, '05 ZT 190

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

Afternoon all. As I have mentioned elsewhere on this rather excellent forum I have recently acquired an '05 ZT 190. It has had little use for a couple of years, maybe that's why the air con doesn't work.

So, I searched the forum and read up on non-working air con, not a five minute job! I went through Jules's test procedure, cooling fan does not work at all. Compressor clutch can be made to engage by bridging the relay contacts.

This then means that when the engine starts too get hot the cooling fan will not cut in. Would that be right? The temperature gauge stays steady showing no signs of an overheat. If the engine overheated would this not show on the gauge? Or a warning light/message?

Also there is no resistor fitted, does this fitment depend on the type of fan, 2 or 3 speed? If I need a new cooling fan, whats available?

John

Quote:

Originally Posted by White horse (Post 2365067)

I went through Jules's test procedure, cooling fan does not work at all.

If the fan doesn't respond to any of the tests, then it may not receiving power to the relays. It's unlikely that all/both speeds have failed. An 05 registration would typically have the later, resistor controlled 2-speed system, but anything's possible. Check the 80amp fusible link in the under bonnet fuse box. If there's one in position, remove it from the car and do a continuity test.

Quote:

This then means that when the engine starts too get hot the cooling fan will not cut in. Would that be right?

From what you've described, yes. The engine does require a reliable cooling fan, as does the aircon system.

Quote:

The temperature gauge stays steady showing no signs of an overheat. If the engine overheated would this not show on the gauge? Or a warning light/message?

Unfortunatly, the 'temperature gauge' is of little use. It's designed to stay 'normal' for all engine temperatures between 75°C and 115°C. Since one is too cool for normal running and the other is too hot, you don't actually know what's happening.

Normal running temperature is around 90°C give or take a couple of degrees. It will rise above this in stationary traffic, so the fan is needed. It should trip on at low speed at 100°C.

Use the Trip Screen Diagnostic Mode (section 7) to find out what's happening.

Diagnostic Mode: http://www.the75andztclub.co.uk/foru...ad.php?t=55585

Quote:

Also there is no resistor fitted, does this fitment depend on the type of fan, 2 or 3 speed? If I need a new cooling fan, whats available?

Resistor control was introduced with the 2-speed fan system for the V6. Later models like yours usually have this arrangement, but there is a degree of inconsistancy.
Before thinking of replacing the fan, you must first confirm which system you have. Resistors are usually visible, but odd ones were fitted out of sight. A definitive check is to take the bumper off and examine the fan motor or the control box. The 2-speed motor has two wires entering the case. The older 3-speed system has four.

EDIT: Bumper removal is easy:https://www.youtube.com/watch?v=7BUGH4_VMkU

TC

My thanks to T-Cut for the excellent info. Put the car in to the Trip Screen Diagnostic Mode (section 7) and went for a drive. Temperature quickly went to about 90 and stayed between 88 and 95 degrees. I drove a mixture of town and country and it was only when I left the car idling on the drive that the temperature went over 95, I let it go to 102, the fan did not cut in so I stopped the engine. Looks like its a bumper off to find out whats going on.

Again, my thanks to T-Cut for the information.

John

Hello, please excuse me hijacking the thread but I talked my son into a ZT pre facelift and he bought a 1.8 injection. The problem he has is that the rad fan is cracked badly in a few places with one fan blade only held on by about an inch of uncracked plastic. Could someone possibly tell me if the facelift fan, radiator assembly will fithis car and if he is able to use a different cc fan for his 1.8.
Best regards, Alan

Front of the car off and had a look at the fan, 4 wires leave the control box and go in to the fan, would that be a 3 speed fan? The fan control box has three relays(?) inside. I have disconnected the wiring to the fan, the piggy back job on the chassis rail, if I reconnect that and try the demist test I should hear one of the relays click, would that be right?

Also, no sign of a resistor, the usual mounting point shows no evidence of holes ever having screws in them. More evidence of a three speed fan?

Very common issue ;in the best case your brushes look like this :

http://rovermg1.free.fr/rovermg/thum...aqmjBueBbR.jpg

See Jules for aftermarket solution :shrug:

Mike

Quote:

Originally Posted by White horse (Post 2365884)

had a look at the fan, 4 wires leave the control box and go in to the fan, would that be a 3 speed fan?

Yes, you have the earlier 3-speed system.

Quote:

The fan control box has three relays(?) inside. I have disconnected the wiring to the fan, the piggy back job on the chassis rail, if I reconnect that and try the demist test I should hear one of the relays click, would that be right?

All else being in place, yes. The relay should trip power to the (slow speed) fan. The usual cause of this problem is failure of the motor brushes.

Quote:

Also, no sign of a resistor, the usual mounting point shows no evidence of holes ever having screws in them. More evidence of a three speed fan?

Yes, the resistor is only present in the later 2-speed system. The fan guard bracket is there but it won't ever have had a resistor on it.

You have two options. Try to rebrush the motor or replace the whole shebang with a later 2-speed system (or the aftermarket alternative), including control box (all plug and play).

If the fan tests failed to run the fan at any speed at all, then I reckon your chances of recovering the old motor are pretty slim. Examine the commutator if you fancy a go.

There's a Howto rebrush the motor and recommended suppliers if you do a key word search using the Google based search system: https://cse.google.co.uk/cse?hl=en&c..._YDw#gsc.tab=0

TC

I am surprised I have a 3 speed fan in such a late built car.

Tomorrow I'll reconnect the wiring and do the demist test, hopefully that will trip a relay

If that works I'll do this; reading back through the forum I came across instructions from Jules that involves swapping wires around that converts a 3 speed to 2. I'll give that a go, if it works then I'll try a re-brushing.

John

Worked out how to feed 12 volts into the fan motor, no life in it so it looks like a new fan.

Also checked continuity in the wiring, all OK.

I did this with the fan and control unit unplugged from the loom so as not to risk damage elsewhere. Would it be possible to do voltage checks with the fan and control box connected to the loom?

Quote:

Originally Posted by White horse (Post 2366223)

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