Diesel aircon fan (Another one)

TheTransporter · 7th December 2020, 00:20

Hi all,

So since owning the ZT CDTI the aircon has never worked.
I bridged the connector block, checked the fuses, etc, and the fan has never moved.

So today I swapped over the silver to the gold resistor.

Still nothing.

When bridging the the little connector block, the compressor starts to run.. but no fan.

So I'm wondering, will the fan not come on if the aircon needs regassing? I haven't had it done yet.

Also... some cars, the aircon is disabled below a certain temperature... it was 3degrees when I was testing it.

Any advice on where to go next?

TriumphStag · 7th December 2020, 08:47

With most vehicles, if there is insufficient gas pressure, then it will prevent the compressor from starting to prevent it being damaged. I would imagine that the 75 is the same.

I would suggest getting it on a vac test to see if there are any leaks (I would imagine there would be if it has never worked). Many re-gas places will do this first and most don't charge if the system does not hold a vacuum.

Arctic · 7th December 2020, 08:59

Quote:

Originally Posted by TheTransporter

Hi all,

So since owning the ZT CDTI the aircon has never worked.
I bridged the connector block, checked the fuses, etc, and the fan has never moved.

Quote:

So today I swapped over the silver to the gold resistor.

Still nothing.

When bridging the the little connector block, the compressor starts to run.. but no fan.

Quote:

So I'm wondering, will the fan not come on if the aircon needs regassing? I haven't had it done yet.

Also... some cars, the aircon is disabled below a certain temperature... it was 3degrees when I was testing it.

Any advice on where to go next?

Hi Marc.
Now you have added the gold resistor in place of the silver one, have you tried the demist test, ignition to II make sure all the A/C is in the off position, then press only the demist button go to the front grill and see if the fan is running continually.

If the fan is not running then you need to do more investigation, wiring, relays, maybe the PCB board is damaged.

TheTransporter · 7th December 2020, 09:14

Hi guys thanks for the replies.

The front end behind the bumper is pretty manky looking, so I'm going to replace the intercooler and condenser.

I have checked all relays and fuses, which are fine,so I might just bite the bullet and replace the fan unit to.

Are there any favoured brands for the 3 items?

SD1too · 7th December 2020, 10:28

Quote:

Originally Posted by TheTransporter

... I might just bite the bullet and replace the fan unit ...

Hello Marc,

With a gold resistor fitted you'll most likely be wasting your time and money doing that. Arctic has given good advice (he owns a diesel too); do the "demist test". It only takes two minutes.

To make diagnosis easier, I'd recommend that you book a mobile, independent self-employed specialist to check and recharge your air conditioning. There will then be no doubt about the fan's operation. Even though they'll be cheaper, don't use the Fast-Fit boys or a general garage for this work.

Let us know about the demist test though Marc.

Simon

Arctic · 7th December 2020, 10:59

Quote:

Originally Posted by TheTransporter

Hi guys thanks for the replies.

The front end behind the bumper is pretty manky looking, so I'm going to replace the intercooler and condenser.

I have checked all relays and fuses, which are fine, so I might just bite the bullet and replace the fan unit to.

Are there any favoured brands for the 3 items?

Marc
The intercooler may only need cleaning out, if its not holed in anyway no point in changing it, if you remove the intercooler make sure you add new O-rings Viton.

1

How did you get to the relay's in the fan control box ?

2

Most two speed fans last it is the silver resistor that fails, and needs changing for the gold one which you say you have done.

3

4

If the condenser is poor that would still not stop the fan from running on the low speed.

Be careful purchasing condensers as some with some the brackets do not line up and you have to do a little work to sort this out, not an hard job.

TheTransporter · 7th December 2020, 20:33

Thanks for the replies guys.

Yes I have tried the demist test, and not a sausage.

I haven't opened the control box, I didn't realise it was servicable. I have a day off Wednesday, so I will have a look.

Regards the intercooler, it looks pretty awful, so I don't mind spending a few quid.
The same goes for the condenser, the fins are almost all none existent.

Arctic · 7th December 2020, 22:37

Quote:

Originally Posted by TheTransporter

Thanks for the replies guys.

Yes I have tried the demist test, and not a sausage.

I haven't opened the control box, I didn't realise it was servicable. I have a day off Wednesday, so I will have a look.

Quote:

Regards the intercooler, it looks pretty awful, so I don't mind spending a few quid.

The same goes for the condenser, the fins are almost all none existent.

Hi Marc.
The intercooler can be cleaned inside and out if removed from the car, it is most likely road dirt, and or black gunk from the O-rings failing at sometime.

I have used these condensers before but as i say some need a little modification with the bracket lining up.

https://www.ebay.co.uk/itm/CONDENSER...T/283687728162

SD1too · 8th December 2020, 08:02

Quote:

Originally Posted by TheTransporter

Yes I have tried the demist test, and not a sausage.

Thanks Marc. That strengthens the possibility that your fan isn't working which will affect the efficiency of the air conditioning.

Quote:

Originally Posted by TheTransporter

When bridging the the little connector block, the compressor starts to run.. but no fan.

I think you're referring to the trinary switch connector here. You must have bridged pins 1 & 4 (black/red & red/black) to trigger the compressor. If you now bridge pins 2 & 3 (black & yellow/grey) does the fan run (high speed)? You'll need the ignition switched on.

Quote:

Originally Posted by TheTransporter

I have checked all relays ... which are fine ...

The relays are in the control box which you say you haven't opened. However they very rarely, if ever, fail. When you do open the box, check that it has a PCB inside as shown in Arctic's photo (it has been known for a petrol fan/control box assembly to have been installed in a diesel which won't work!).

Thanks for your helpful replies so far.

Simon

TheTransporter · 8th December 2020, 23:43

Thank you for all the replies so far guys, it's appreciated.

Simon, yes I did bridge the pins on the trinary switch, as you said, pins 1+4 does trigger the compressor, but pins 2 +3 didn't do anything at all.

When I said relays, I meant I checked all the fuses listed in the fuse boxes.
I have tomorrow off of work, so I'll find an hour 2 for some more fault finding.

Arctic... I was a actually looking at that on eBay this morning and wondering if it was of decent quality. You have answered my question!

7th December 2020, 00:20	#1
TheTransporter Newbie MG ZT Join Date: Aug 2020 Location: Torquay Posts: 24 Thanks: 2 Thanked 0 Times in 0 Posts	Diesel aircon fan (Another one) Hi all, So since owning the ZT CDTI the aircon has never worked. I bridged the connector block, checked the fuses, etc, and the fan has never moved. So today I swapped over the silver to the gold resistor. Still nothing. When bridging the the little connector block, the compressor starts to run.. but no fan. So I'm wondering, will the fan not come on if the aircon needs regassing? I haven't had it done yet. Also... some cars, the aircon is disabled below a certain temperature... it was 3degrees when I was testing it. Any advice on where to go next?

7th December 2020, 08:47	#2
TriumphStag Gets stuck in MK1 Connie SE 2.0CDTi Tourer Join Date: Mar 2012 Location: Crawley Posts: 635 Thanks: 39 Thanked 79 Times in 52 Posts	With most vehicles, if there is insufficient gas pressure, then it will prevent the compressor from starting to prevent it being damaged. I would imagine that the 75 is the same. I would suggest getting it on a vac test to see if there are any leaks (I would imagine there would be if it has never worked). Many re-gas places will do this first and most don't charge if the system does not hold a vacuum.

7th December 2020, 09:14	#4
TheTransporter Newbie MG ZT Join Date: Aug 2020 Location: Torquay Posts: 24 Thanks: 2 Thanked 0 Times in 0 Posts	Hi guys thanks for the replies. The front end behind the bumper is pretty manky looking, so I'm going to replace the intercooler and condenser. I have checked all relays and fuses, which are fine,so I might just bite the bullet and replace the fan unit to. Are there any favoured brands for the 3 items?

7th December 2020, 20:33	#7
TheTransporter Newbie MG ZT Join Date: Aug 2020 Location: Torquay Posts: 24 Thanks: 2 Thanked 0 Times in 0 Posts	Thanks for the replies guys. Yes I have tried the demist test, and not a sausage. I haven't opened the control box, I didn't realise it was servicable. I have a day off Wednesday, so I will have a look. Regards the intercooler, it looks pretty awful, so I don't mind spending a few quid. The same goes for the condenser, the fins are almost all none existent.

8th December 2020, 23:43	#10
TheTransporter Newbie MG ZT Join Date: Aug 2020 Location: Torquay Posts: 24 Thanks: 2 Thanked 0 Times in 0 Posts	Thank you for all the replies so far guys, it's appreciated. Simon, yes I did bridge the pins on the trinary switch, as you said, pins 1+4 does trigger the compressor, but pins 2 +3 didn't do anything at all. When I said relays, I meant I checked all the fuses listed in the fuse boxes. I have tomorrow off of work, so I'll find an hour 2 for some more fault finding. Arctic... I was a actually looking at that on eBay this morning and wondering if it was of decent quality. You have answered my question!