AC not turning on at all??

[Outatime]

Dear All,

I haven't used the air con for ages, and today I tried turning it on... the interior fan doesn't turn on, neither the compressor engauges to the running belt. It's just like nothing happens.

(And the radiator fan doesn't turn on too... though it turns on fine when the coolent is in the right temperature, so the radiator fan should not be a problem to this matter)

I have checked the all the fuse, and the voltage in the car is plenty for the compressor to engauge.

Is there anything i should look out for? The AC system works fine before...(apart from a slow R12 leak somewhere)

Thanks!

[bozzzydmc]

If the system is low on gas then the low pressure switch wont let the compressor run.

The interior fan has nothing to do with this so thats a separate issue. It could be that your blower motor circuit breaker is at fault you could try swapping it over temporarily with the adjacent cooling fan ( radiator ) one.

Is the wiring attached to the back of the fan speed selector switch ?

[Outatime]

bozzzydmc Wrote:If the system is low on gas then the low pressure switch wont let the compressor run.

The interior fan has nothing to do with this so thats a separate issue. It could be that your blower motor circuit breaker is at fault you could try swapping it over temporarily with the adjacent cooling fan ( radiator ) one.

Is the wiring attached to the back of the selector switch ?

Thanks Mike!

Will regas the compressor and see if things turns out ok.

Will also check on the wiring behind the selector switch... it might have come loose after I did some work on the headlight switch relay kit and the head unit.

Will keep you update Thanks a million!

[NickT]

The low gas pressure switch is behind the front right wheel.
TEMPORARYILY short this switch out and see if the air-con compressor clutch engages.
If it does then you are low on gas/ have a leak etc etc

Check the interior fans by puttint the mode switch to "VENT" then operate the interior fans.
If they don't power up then as Mike said check the wiring especially the circuit breakers.
Again you can TEMPORARILY link across the circuit breaker with a FUSED section of wire to see if the fans come on.
If they do then you need to replace the circuit breaker, ideally with the uprated one.

NickT

[Outatime]

NickT Wrote:The low gas pressure switch is behind the front right wheel.
TEMPORARYILY short this switch out and see if the air-con compressor clutch engages.
If it does then you are low on gas/ have a leak etc etc

Check the interior fans by puttint the mode switch to "VENT" then operate the interior fans.
If they don't power up then as Mike said check the wiring especially the circuit breakers.
Again you can TEMPORARILY link across the circuit breaker with a FUSED section of wire to see if the fans come on.
If they do then you need to replace the circuit breaker, ideally with the uprated one.

NickT

Thanks Nick

What does the low gas pressure switch looks like? I tried looking for it just now but I don't see anything that looks like a switch? (my RHD AC have some custom mod... maybe that have moved it elsewhere?)

[Chris Hawes]

If you go to get a pressure check ensure dye is put in so that if there are leaks they can be traced. Some places in the UK will check a system for free and will only charge you for re-filling. Is this also the case for Hong Kong?

If the capacity is like the LHD versions you should be able to hold around 900g of R134a (assuming the system has been converted). The tell tale signs are the different connectors on the compressor.

[Outatime]

Chris Hawes Wrote:If you go to get a pressure check ensure dye is put in so that if there are leaks they can be traced. Some places in the UK will check a system for free and will only charge you for re-filling. Is this also the case for Hong Kong?

If the capacity is like the LHD versions you should be able to hold around 900g of R134a (assuming the system has been converted). The tell tale signs are the different connectors on the compressor.

I think they put in dyes last time i regassed, but they didn't do any check so it was useless :evil: Will go to another garage and do it again properly.

Is the capacity the same for R12?

R12 is still available over here, and my D is still running on it.

[Darren C]

Outatime Wrote:

Chris Hawes Wrote:If you go to get a pressure check ensure dye is put in so that if there are leaks they can be traced. Some places in the UK will check a system for free and will only charge you for re-filling. Is this also the case for Hong Kong?

If the capacity is like the LHD versions you should be able to hold around 900g of R134a (assuming the system has been converted). The tell tale signs are the different connectors on the compressor.

I think they put in dyes last time i regassed, but they didn't do any check so it was useless :evil: Will go to another garage and do it again properly.

Is the capacity the same for R12?

R12 is still available over here, and my D is still running on it.

Hi,

If they put dye in it last time you'll find a leak with a UV lamp, glows green like the blood on the movie Predator
You simply cannot add R134a with out changing the expansion valve. The fitting on the compressor can remain the same 3/8 or 1/4BSP as long as you label the system. If you want to change to R134a connectors there about £40 each as its an instantaneous fit type, rather than threaded schrader. The Coefficient of R134a is slightly different to R12, and as such it runs at a higher pressure. You can some times get problems with old systems such as compressor seal failure after changing gasses.
If you can get R12 and it's still legal where you are then thats the best solution. Alternatively if you cant get R12 you can get a "drop in" such as Iceon 59 its a HFC rather than an HCFC that R12 used to be, so still quite legal, and you don't need to change expansion valves or anything else come to mention it.
Make sure you do a nitrogen pessure test before you add any gas as it'll prove system integrity, find any leaks and prevent expensive top ups in future.

Best Regards
Darren
ACRIB (Air conditioning and Refrigeration Industry Board) !!

The LP switch looks like a standard transducer with a twin wire connector, mounted usually inverted on the suction line, its behind the RH front wheel on the D as Nick T said

[Phil Peters]

Hi Darren,

Just out of interest, would you need to use a different type of compressor oil if you were running Isceon 49?

Cheers,

Phil

[Darren C]

Hi Phil,

No that's the beauty of a drop in. If you go down the R134 route you'll need to change from mineral to ester oil. It's near impossible to clean out the system of old oil and and if you are unlucky they will "wax" at the expansion valve and cause a blockage.
If your system has already got dye in it you can buy a black light (UV) pen torch for £15 from Camberley Auto's. Not as good as a professional lamp, but hey they start at £400. If you put the car in the garage and turn off your lights, or do the leak check at night you'll get a good result with the pen lamp.
Before you go leaping in with spanners it's always worth cleaning any old dye traces off first with a special dye cleaner, as they may just be from old leaks some one as previously cured. Alternatively if your system still runs and you suspect a low gas/leak, soapy water usually bubbles up around a suspected area.

The most common cause of a/c leakage in a car is lack of use. The gas escapes from the compressor pulley seal over time. The seal is made when running and benefits from its oil supply (in the gas circuit). If the car stands or you don't run the a/c often, the seal dries out and bye bye gas. The other place is the condenser by the rad at the front of the car. Death by stone impact or corrosion.
Other than that human error, not pressure checking properly after repairs etc. Although as our cars age, so do all the nitrite o seals.

Just one last point to note is that "drop in gas" is expensive compared to conventional gas. R134a is around £8Kg Iceon 59 is £50kg, but you save on all the other parts and work required in the long run compared to changing gas.

Any drop in is what's called a blend. This is a mix of refrigerants to give a similar characteristic to the "copied" gas. Unfortunately with blends, the mix of individual component gasses evaporates at different rates. This isn't a problem in a good gas tight system, but if you have a tiny leak, the gasses in the blend escape in order of their molecular size and rate of expansion. The resultant mix left in the system is useless.
That's why it's paramount to do a nitrogen pressure or strength test on the system first, and a full vacuum evacuation afterwards.
This is usually 1.3 x max working pressure for a few hours, overnight is best. Probably best left to the experts as this can be upto 30bar on the highside, but it's nice to understand what's needed.

Good luck
D

[Darren C]

One important thing I forgot to add was DO NOT use any of these so called top up aerosol cans unless you want to spend £100's on a new compressor.
1 They are illegal as of this year.
2 Some on the market are from places the other side of the iron curtain and do not contain what they say on the tin.
3 Any system contains a finite weighed charge, over charge it and you destroy the compressor.
4 Any blend as I said earlier is a mix, so you can only charge as a liquid, if you try to charge as a gas only, you'll end up with the wrong characteristic and poor cooling, over heating of the compressor and another expensive bill.

That should be enough to put you off!

Best regards
D

[Phil Peters]

Cheers for the info Darren, interesting stuff

I haven't checked the A/C system yet but when I get the fuel tank back in the car I'll fire up the engine and give it a razz. This one's been stood for most of it's life so I wouldn't be surprised if the compressor won't kick in due to low refridgerant levels. But you never know!

[Darren C]

You could also try a new drop in RS24, a better/more stable blend than the Iceon range.

Details below

http://www.acr-news.com/news/news.asp?id=860

Top tip, if you link out your LP switch to test the compressor run circuit/clutch, dont do it for too long (a minute max). As you may run the compressor seal dry, and burn it out or damage the seal edge.

Best Regards
D

[Darren C]

All you need is here;

Page 9 of 88 shows the pocket UV light pen £16.75 from Camberley auto factors. Their part ref is 7301.

http://holod-konsultant.ru/yabbfiles/At ... atalog.pdf

Regards
D

[Chris Hawes]

Don't forget to spray some WD40 or other lubricant on your compressors moving parts as they can get a little stuck (mine did from lack of use).