Trying to get the air-con working.

[bx petrol auto saloon]

Dear Mat,
Thanks ever so much Mat I have just been out and had a shufty, there doesn,t appear to one fitted. Mind you I still have the white portion of the heater control panel still soundly fitted with all its four screws, so getting to see behind it is a little difficult
But I will take your word that it isn,t connected with the air-con Mat and thank you for all the kind advice Mat
The first thing I need to sort out is why the cold air control won,t so round to fully cold or fully hot either once I have that sorted then I start upgrading the air-con system to R 134a
Vince,

[Way2go]

The first thing I need to sort out is why the cold air control won,t so round to fully cold or fully hot either

Hi Vince, this is likely as I posted before that the heater valve is silted up. This hot/cold control operates this valve by cables.
Keeping flushing solution in the system (Barr's Professional Flush) for a few days and running the car with the valve at hot first and moving it back & forth may shift the silt, but it may be necessary to replace this heater valve if this doesn't shift the crud back into solution.

[bx petrol auto saloon]

Dear W2G,
Firstly, thank-you so very much
Secondly, does the heater tap, split into 2 halves, or is it a one piece unit
Would I be able to get a new one from anywhere
I will start to remove the heater tap, first thing tomorrow
Many thanks,
Vince,

[Mothman]

Hi Vince, the heater tap unit is a one piece. I have a spare if you want one. PM me and we can chat more about it.

Andy

[BX Bandit]

Vincent, just in case you don't know you need to drain the coolant out with the cabin heater control dial on hot as far as you can.
The micro switch on heater control dial is mounted on the back of the white assembly you mention. Neither that micro switch or the air recirculation micro switch will not cause the air con to mal function.
However, the sliding control (a potentiometer) can either home worn or get dirty, meaning the circuit is made. It is also held on by two aluminium tabs that are twisted to keep it 'mounted' to the white panel. If its been removed a few times these little tabs fatigue and fall off.
As you slide the potentiometer, you should hear the air con control relay click in. The control relay is mounted somewhere in the cabin, close to the three heater/ventilation/fan speed dials.
Along with the control relay click, you should hear the engine radiator cooling fans come on

[Vanny]

Don't replace the r12 if the system is suitably charged. R12 is a much better refrigerant than r134a, more so when the expansion valve tonnage is tuned to r12.

This link will show you how the control panel should look from the back

http://www.bxproject.co.uk/gallery2/v/A ... 4cca52a5cc" onclick="window.open(this.href);return false;


The heater tap is in three pieces.
Read more on heater tap removal here

http://www.bxproject.co.uk/phpbb3/viewt ... f=2&t=3808" onclick="window.open(this.href);return false;

[bx petrol auto saloon]

Dear Andy,
Firstly, thank-you very very much indeed Andy, it is really kind of you offer another heater tap Andy
Secondly, I wanted to answer your most kind offer, on the forum Andy, because I didn,t want you to think that if you hadn,t heard from me with a pm, that I wouldn,t be interested.
These problems, with the car take me ages to sort them out, much much longer than it takes most people to do these things Please don,t think ill of me if I don, t reply for a week or 2
Once again thank-you so very much Andy
Vince,

[bx petrol auto saloon]

Dear BX Bandit,
Firstly, thank you so very much for your very very kind reply.
Secondly, this removal of it,s coolant will be time no.5 for the same fliud Because the heater tap won,t go onto hot, this makes me have to remove quite a few hoses, to make sure that the system is bled properly.
With regard to the micro switches, I could only find one and that one was for the recirc switch. And after reading your most informative reply quite a good few times and also looking at Vanny,s very kind pics, the penny finally dropped
Today I carefully gingered out the white heater control panel and all of a sudden the air-con relay and the two air-con fans started working So I removed the two wires connected to it and carb cleaned them and spray greased them, tightened them and refitted them both and they were still working, so I have refitted the white part of the heater control panel and given it good ole thumping on the top of the cover of the for the potentiometer and up to now it hasn,t packed up So thank-you so very much indeed for that one ( I wouldn,t have had a clue on that one ) and at least now if packs up again, I will now where to look next time. I did try starting the engine to see if the air-con was working, but unfortunately it still isn,t working, but atleast we are one big step closer to getting it working
Many thanks indeed, I could,t have done that without your very very kind advice, thank you so much indeed
Vince,

[Way2go]

Hi Vince, you will also find that with the factory air-con set up you can also switch the radiator fans to run full time overriding the standard thermo switch. This is especially useful when sitting in crawling traffic in a traffic-jam preventing the water from overheating & this works even if the air-con is not functioning.
Just use the air-con on/off switch on the dash and you can test this out for yourself on your drive with the engine idling.

[mat_fenwick]

However, the sliding control (a potentiometer) can either home worn or get dirty

Very good point, I've had to replace mine once already. For future reference for anybody reading this thread, it's a 10k ohm linear potentiometer, with a Valeo part number of N22-109968C (it's on my desk as I type ) I couldn't find a linear pot of the right dimensions, and made do with a rotary pot until I could find a second hand one.

[bx petrol auto saloon]

Dear Vanny,
Firstly, thank-you so very very much indeed for your really kind reply and to for your idiot proof diagrams and pictures aswell
Secondly, I havn,t drained the old air-con fluid yet Vanny There was what seems to have been a bad connection where the 2 small wires that fit onto the potensiometer for the air-con switch, I have cleaned, lub,d and removed and tightened them aswell. As I was working on her today I touched something around there and all of a sudden the air-con relay started working and the two fans in front of the car also started workling After reassembly and some vigarous thumping it still seems to be working really well. I did start the engine on her with the newly working air-con relay and her fans, but unfortunately it still isn,t working. But we are one massive step closer today thank-you very much Brill.
I think when it finally comes to draining the old air-con fluid I will try to take the car somewhere local where they can drain it all out properly and then I can make a start on up grading her
Thank-you so very Much Vanny for all of your extemely helpfull advice and help
Vince,

[Mothman]

No worries Vince, its not going anywhere, ready when you are. Dont think you are that far away from me so could always drop it round.

Andy

[bx petrol auto saloon]

Dear All,
Hopefully Shari has downloaded some pics, that may help, they are a little blurry because I forgot to press the button to focus them.
Fingers crossed
Vince,

[Vanny]

Vince, what im saying is that if the system is charged, there is no reason to recover the refrigerant gas!

You need to see if the compressor is engaging or getting a supply voltage when you flick the switch.

IF the compressor is working, then the centre of the compressor pulley should be rotating with the belt.

[Way2go]

/\ As I understand it that is not all. R12 is quite a high pressure system and as such has a pressure microswitch in the system to detect when the gas pressure falls below a threshold. The purpose of this is so the clutch does not engage when the pressure is low and hence damage the pump by making it potentially run dry.
The alternative refrigerants I believe are not such high pressure as R12 and IIRC there may be an issue then requiring a change of this pressure switch.

So ........ switching the system on does not mean you will get power to the clutch if the refrigerant is no longer fully charged irrespective of a hiss from a quick tap on the schrader valve?