Air conditioning failure
 

Well it looks like the good weather is upon us again and sadly my air-con ain't working, it was serviced last august and re-charged by an independent, but i thought it was a bit pricey at £140 for a couple of hours work, have been switching it on every so often during the winter months as i was told to do, but it ain't working anymore, when i switch it on the compressor at the front of the engine turns for about 4 seconds then stops for the same time and keeps doing this, has anyone out there suffered from this problem or might know what will cure this problem, i thought it might be a faulty relay but i don't even know if there is one on the air-con system, the car is a 1996 850 2.5 10v CD, any advice would be great. Thanks, John

RE: Air conditioning failure
 

It sounds like you're low on refrigerant which, given the system was recharged last year, probably means you've got a leak.

The AC system is the achilles heel of the 850. I hope for your sake that it's something simple like a loose connection but there's a good chance that the evaporator is the problem. It's a pretty big job to change it because the entire dash has to come out.

You can get the system recharged with coloured dye to see if and where it's leaking.

RE: Air conditioning failure
 

Thankyou for the reply, im hoping it's just needing a recharge because i don't think i could justify the cost of a new evaporator. Will book it in tomorrow as im sure i was told it was guaranteed for a year and that i would get a free recharge if there was a problem, but as usual i can't find the receipt, so much for my relay theory ha ha. the car was fitted with the dye you were on about as there was a sticker under the bonnet saying this when i got the car back in august, but i can't see any traces of the dye anywhere. thanks again john.

RE: Air conditioning failure
 

In theory the system should never need recharging, unless it's got a leak.
You don't have your fridge and freezer recharged every year do you?

RE: Air conditioning failure
 

Its more than likely leaked its refrigerant,R134A im guessing,i dont know much about air con but one of my dads business' do air con so picked up a bit over the years,
I couldnt tell you where the leak is most likely to be though,im not that familiar with 850 air con,
The reason it was 140 quid was the price of the gas,its really expensive,
I have put a custom aircon system in my 242 and if the 850 system is similar my guess is the condensor is cracked,but as someone already suggested it may well be the dreaded evaporator...

RE: Air conditioning failure
 

the reason that most car air con systems lose refrigerant to some degree over time is due to the fact that have to operate in a enviroment that is somewhat harsher than your average fridge, the ideal conditions for a refrigeration unit are vibration free, and in constant use ,therefore two main problems arise in a car system,one, most car systems are used infrequently(in the uk at least) which causes seal degregation due to seals "drying out", and two, couple this with the constant flexing/stress inflicted on joints etc caused by extreme heat fluctuations, vibration etc, all lead to some losses being inevitable, however this amount should not be more than about 15 percent per year, anything more would suggest a "real" leak, the best preventive medicine for a air con system is use it as often as you can

RE: Air conditioning failure
 

>In theory the system should never need recharging, unless
>it's got a leak.

Yup, good theory.

>You don't have your fridge and freezer recharged every year
>do you?

Nope - but then fridges / freezers tend to use slightly different materials for certain components; don't have to work with the heat, virbation, and other environmental and external issues of a car engine bay, and perhaps lastly of most importance - tend to be used almost continuously.

RE: Air conditioning failure
 

You won't see any leak with the dye unless you use an ultra violet light. At least, thats how my leak on my old senator was found.

Gary

RE: Air conditioning failure
 

Another reason fridges don't usually leak is that the motor driving the compressor is sealed inside the compressor unit and the only connection to the outside world is electrical. There are no moving parts to be sealed. Since at present a car aircon compressor has to be driven from the engine, the input shaft to the compressor has to rotate through a seal and it's not perfect. If this seal is not kept lubricated by running the aircon regularly, it dries out and up goes the leakage rate. So, unfortunately, recharging has to be regarded as a maintenance operation.

Martin Cox

RE: Air conditioning failure
 

Our local air con guy charges around £50 for a re-gas
Were over in Derby.

Regards
Mike

RE: Air conditioning failure
 

my t5r was doing this and when the guy checked it he said there was a some gas still in it. when he let some out the compressor woulndt run at all. so you might just be low. if you get a uv torch from maplins or some where you can check the system your self. to check the evaporator take out the resistor box or if you want a better look take out the fan as well. i dont think many aircon people will bother doing this. also the guy that did mine charged £58.75 all in, including topping up my dye. check they weigh the gas going in and make sure the system is temperature checked also. my guy put a thermometer in the centre vent and shut the doors put it on full cool, he said it should reach between 3c and 6c mine hit 3.1c. while youve got the fan out it might be an idea to clean the evap unit, especially if youve not got a pollen filter fitted. the guy that did mine also said he could do an evap unit change for about £300, if it is your evap unit. and the best thing is he came to my door to do the job. anyway heres his details:

Vehicool
68, Ripon St
Lincoln Lincolnshire
LN5 7NQ

Tel: 01522 575858

i found him through this web site:

http://www.autoclimate.com/welcome.html

warning not all of the people on this database charge the same. i think its like a yellow pages type search system.

RE: Air conditioning failure
 

so everyone has to have their units recharged every year?
The system is sealed the same a home unit except for the drive on the pump.
Therefore if the seal is ok it should'nt leak.

RE: Air conditioning failure
 

>so everyone has to have their units recharged every year?

Not necessarily.

But they will need their AC recharging when the level of refrigerant is low enough to affect the compressor working effectively.

>The system is sealed the same a home unit except for the
>drive on the pump.

It is not used / operate in the same way as a fridge, and it's not subject to the same adverse conditions.

>Therefore if the seal is ok it should'nt leak.

In an ideal world, it shouldn't.

Yet they do - quite frequently.

And leaks can be quite difficult to trace, even with dye and UV lighting. And when they are found, they can be rather minor - yet probably quite expensive to put right.

You can bombastically claim it's just like a fridge, therefore it shouldn't leak - but they do, and you'd be wrong - it's not *just* like a fridge, and it's not used just like a fridge, and it's not able to operate in quite the ideal circumstances that a fridge is.

The bottom line, is that car AC systems do tend to leak over time. Sometimes it's minor, and more effort and expense than it's worth to find the leak. Other times it may be more obvious.

But regardless, it's quite easy to detect when a car AC system is low on refrigerant.