406oc.co.uk

Hi All, New to the club and the 406 but the info so far has been very helpful.

I have one quick question - I bought the car from a good mate who said aircon worked fine but having now tried it the air does not get colder when switched on so I suspected it needed regassing. However when the a/c button is operated on the dashboard there is no click or drop in revs as the compressor kicks in - something I have been used to in other cars.

Any ideas/suggestions would be of assistance or are my fears correct and the comp is not functioning.

Thanks again for the help - it is greatly appreciated.

Steve

my a/c is knackered it has a hole in it however i asked all the same questions when i got my 406 and i was told in answer to your question:-

if the coolant level is below a certain level it will not come on hence no click

if it is knackered it will not click.

go to kwik fit they charge £45 for a re-gas however if they are unable to re-gas it they will not charge you anything, so its a free check in a round about way.

If the outside temp is below 3 deg C the compressor will NOT run, this is part of the controls circuit.

Maybe it's been too cold?

Generally though, if your sure the compressor does not run then it is possible that the gas has leaked from the condenser radiator (common problem I'm afraid) budget for £300.00 to fix. I had mine done last summer and it's been fine since.

You can see the compressor running if you look at the end of it's 'clutch' when it engages and clicks in then you will see the end of it spinning round.

Hope this helps, and Welcome!!


Welton.

Welton wrote:If the outside temp is below 3 deg C the compressor will NOT run, this is part of the controls circuit.

Maybe it's been too cold?

welton
this only applies to the d9's
the a/c will run whatever the outside temperature is on a d8

the problem could be
seized compressor
no gas
too much gas
blocked part of the system
break in compresor/or climate control circuit

the favorite for the 406 is the condenser
it rots away at the bottom and all the gas leaks out and the low pressure switch disables the compressor

Why on earth would they stop the compressor running in the cold - that's when you *really* need it, to de-mist the windows!

Hi All, Thanks everybody for the info - looks like it starts with a re-gas . The outside temps been about 9/10 degrees so fingers crossed its low gas.

On making further enquiries about the car ( which has only travelled 19000 miles since new) the aircon has rarely been used since new.

Thanks again for all your help.

Steve

If you say it's only done 19,000 miles

To be fair, if it's low on gas then it has leaked out. At the same time 'some' leakage is to be expected and is acceptable I think a maximum of 5% system volume per year can leak naturally from O rings in the pipework joints.

A car's engine bay is a pretty harsh place for a refrigeration system.

You may well find that when they pressure test your system then there will be a small leak, if it's not the condenser then maybe a pipework joint somewhere. they will fix this with a new O ring and retest it etc.

You maybe unlucky though and the condenser has corroded, usually 6 to 7 years old is the time for a condenser.

Good luck.

mjb wrote:Why on earth would they stop the compressor running in the cold - that's when you *really* need it, to de-mist the windows!

An interesting question mjb, to which I shall now bore you with the answer

You see, at temperatures below around 3degC the Oil in the refrigerant can no longer travel around effectively with the refrigerant 'flow'. This gives rise to excessive wear in the compressor and will eventually fail and contaminate the whole system with metal filings and all sorts from the compressor breaking up (not good).

So all modern cars, after about 1996 ish have a safety interlock which will not let the thing run in very cold conditions.

In winter, when the ambient temperature is below, say, 5 deg C the moisture content of the air (humidity) is very low as all the moisture normaly carried in the air has 'fallen out' onto the ground as due. Notice that in winter the roads stay wet all day long because the cool air cannot absorb it.

The relatively 'dry' air can then readily absorb moisture from your windscreen/windows once you apply heat to the air and it expands allowing it to hold or 'carry' moisture away.

Admittedly it is not ideal when the car is cold and you haven't got the heater upto temp yet, but by and large it is an acceptable and effective window demisting system.

I thank yaw.

Hello, mjb...........mjbeeeeeeeey........wake up damn you.......wake up!!!!!

Welton wrote:In winter, when the ambient temperature is below, say, 5 deg C the moisture content of the air (humidity) is very low as all the moisture normaly carried in the air has 'fallen out' onto the ground as due.

Ah, but that doesn't hold true once there's humans in a cold car, breathing and radiating heat, which of course causes condensation to occur... My last car didn't have aircon and winter used to be the season for wiping the windscreen with a cloth then driving around for ages with the windows open (brrrrrrrr!)

Hello, mjb...........mjbeeeeeeeey........wake up damn you.......wake up!!!!!

uh? wha? eurgh... Zzzzzzzzzzzzzzzzzzzz

jameslxdt wrote:

Welton wrote:If the outside temp is below 3 deg C the compressor will NOT run, this is part of the controls circuit.

Maybe it's been too cold?

welton
this only applies to the d9's
the a/c will run whatever the outside temperature is on a d8

mines a d8 and doesnt work when cold - i therefore agress with welton as it definately works

Amen !

the a/c in my d8 runs whatever the temperature,
some a/c systems have a switch that cuts out the compressor when there is a risk of ice forming in the reciever dryer, if it didnt the pressure would go too high, some other a/c systems have a thing called an orifice tube, when the temperature of the refrigerant goes below a certain level, the tube contracts and restricts flow, raising the pressure on the high pressure side of the system and the high pressure switch see's this and cuts out the compressor, if the refrigerant is already at this temperature then the compressor will not run

Welton wrote:

mjb wrote:Why on earth would they stop the compressor running in the cold - that's when you *really* need it, to de-mist the windows!

An interesting question mjb, to which I shall now bore you with the answer

You see, at temperatures below around 3degC the Oil in the refrigerant can no longer travel around effectively with the refrigerant 'flow'. This gives rise to excessive wear in the compressor and will eventually fail and contaminate the whole system with metal filings and all sorts from the compressor breaking up (not good).

PAG oil used in R134a a/c systems has a boiling point when pressurised with R134a of about 21c and the freezing point of about -200c, so no matter what the temperature the oil will flow evenly, the compressor also has its own supply of oil to lubricate it, its the same oil as the rest of the a/c system it just serves the purpose of lubricating the compressor whereas the rest is for aiding the heat exchanging process