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Old 2nd September 2021, 10:35   #1
bluemalbert
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Default Cooling Fan Test

I'm continuing to get my 'other ZT' ready for the road and MOT, which is a 2002 ZT KV6 190, having sorted the front suspension last week i'm now on the cooling system.
I have read the 'How To fan test' written by Jules in depth but still find a couple of actions which don't pan out as I read - assuming I have things correct.
Any guidance from knowledgeable peeps will be most welcome!
The Issue: There is an intermittent fault stopping the fan cut in at the temperature it should - 100degrees. It did kick in yesterday once, correctly and stop correctly around 96 degrees but then not again. So I then used the 'How To' to test it.
First: quote: 'set the AC to demist function' My other ZT has the demist button but not this one as its a different (older) panel. (see piccy) So, do I switch on the ignition/aircon/blower/set to windscreen in order to get to the same state as above?
Second: If I'm correct in my assumption - there is no fan action by bridging the gap on the trinary switch plug across the 2 furthest apart terminals, or the two closest together. Then with the engine running, and the AC on, the same test gives nothing across the farthest apart terminals (yellow/grey to black but does give a click ( the aircon clutch I guess) bridging the 2 x closest together.
Ive checked the fuses which Jules recommends but not the control box as Ive not got the front off the car yet - in the hope i may not have to!
thanks in advance
Mal.

dash panel.jpg
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Old 2nd September 2021, 11:37   #2
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Quote:
Originally Posted by bluemalbert View Post
First: quote: 'set the AC to demist function' My other ZT has the demist button but not this one as its a different (older) panel. (see piccy) So, do I switch on the ignition/aircon/blower/set to windscreen in order to get to the same state as above?
Yes. Set the centre rotary control fully clockwise to the windscreen demist position. Does the LED in the 'A/C' button illuminate? If not, press the 'A/C' button so that it does.
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Second: ... the same test gives nothing across the farthest apart terminals (yellow/grey to black but does give a click ...
Great care is needed identifying the wiring colours. There is slate/yellow and yellow/slate! The first colour is the main one and the second is the tracer. Confirm your identification by looking for the tiny terminal numbers moulded into the plastic connectors:

1 = slate/yellow
2 = black
3 = yellow/slate
4 = black

To check the faster fan speed you need to bridge terminals 2 & 3.
Do you have a 2 or 3 speed fan Mal?

Simon
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Old 2nd September 2021, 12:02   #3
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[QUOTE=SD1too;2898180]Yes. Set the centre rotary control fully clockwise to the windscreen demist position. Does the LED in the 'A/C' button illuminate? If not, press the 'A/C' button so that it does.

Hi Simon - the a/c button will only illuminate with the engine running ie not ignition only. When it does .............................see below:

Great care is needed identifying the wiring colours. There is slate/yellow and yellow/slate! The first colour is the main one and the second is the tracer. Confirm your identification by looking for the tiny terminal numbers moulded into the plastic connectors:

1 = slate/yellow
2 = black
3 = yellow/slate
4 = black

To check the faster fan speed you need to bridge terminals 2 & 3.
Do you have a 2 or 3 speed fan Mal?

Sorry for the careless colour ID. Yes I agree with the colours and see the numbers too and can confirm Ive been bridging 2 and 3 with out action! (engine running )
I have no resistor gold or silver that I can see so can only assume its an earlier 3 speed.
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Old 2nd September 2021, 13:29   #4
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Hi Mal,

If your fan motor is the three speed type then it sounds as if you have the common situation of a worn down earth brush. This will knock out the slow speed (needed to cool the engine at 100˚) as well as the medium speed (which is triggered by the trinary switch bridging you've done). This can be repaired economically with new brushes from Engineering Carbon Products in Croydon which are specially made for our motors. I have these fitted to my own car and they have outlasted the originals. Don't be tempted by cheaper inferior offerings on eBay.

Regarding the air conditioning, if the compressor clutch isn't engaging when you press the A/C button the system probably needs recharging but you'll need to fix the fan before dealing with that.

If you need any further help, let me know.

Simon
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Old 2nd September 2021, 13:45   #5
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Thanks Simon, how many brushes are in the 3 speed motor? Also can you give the details of the Mobile Aircon guy in Hownslow. Next job front off!
On a slightly different note, do you know if I can fit some sort of media system for phone etc to the panel I have instead of the single Kenwood head unit - (or even a Hi Line as a last resort!)
Thanks again for sharing your endless knowledge!

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Old 2nd September 2021, 16:00   #6
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There's four brushes, a set of four from ECP is £36, not sure if that includes P&P. I got a set from them for a 1.8T but that was years ago.

Link to brushes you need: https://engineeringcarbonproducts.co...variant/795934

Not a lot of point in contacting an aircon engineer before the fan is sorted.
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Old 2nd September 2021, 11:42   #7
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Default Kv6

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... but does give a click ( the aircon clutch I guess) bridging the 2 x closest together.
This suggests that your air conditioning system is low on refrigerant gas. Don't bridge those two terminals again. Book a mobile independent air con. specialist to check and recharge your system as soon as possible. I don't live too far from you and can recommend one based in Hounslow.

Simon
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