With the first signs of spring-like weather, I've had a chance to try out the aircon on my newly purchased VRS (2006). I'm not convinced it's working properly. What should the vent output temperature be? Is it related to the outside temperature? It was 9.5C outside when I tried it & the air wasn't that chilly coming out of the vents. I will try it on VCDS to check the output temp this weekend, but was wondering what to consider normal as it's potentially another thing for the dealer to fix.

It should feel ice cold.

A/C compressors are known to be a weak point on the earlier cars.

It may just need a regas - take it back to the dealer and ask them to check it over.

what temperature did you set it to?

Would have thought it would come out warm / cold until the interior reaches the set temperature and then regulate the output temp and fan speed to maintain what ever it is set to.

If you have dual zone climate then you just set it to LO and it is ice cold with fans on full.

Not sure with the standard climate though ....

what temperature did you set it to?

Would have thought it would come out warm / cold until the interior reaches the set temperature and then regulate the output temp and fan speed to maintain what ever it is set to.

Set to minimum temp, fan 4.

Fan high and temp on lowest the air exiting the face vent should be about 5 degrees C. The aircon pipe that goes into the car should feel icy cold if it is working. If the temperature between the two air con pipes is similar then you probably need a regass.

Cars with aircon loose 10 - 20 of refigerant per year if only used occasionally. I've always been told to run the aircon for atleast 10 minutes on a monthly basis to help prevent refrigerant loss. Since found that my fuel economy is the smae reagrdless of running air con all the time or going without, so now it is permanently on. Since doing that the Toyota I have hasn't needed a regass in the past 4 years. It gets checked annualy at a local aircon specialist who only charge if work needs to be done on the system. I now run the Superb with aircon on all the time and averaging 51mpg on a tank of fuel. Got the same when I ran it for a week with no aircon running.

The air exiting the vents will always be colder than what it is set to as it needs to cool the ambient air in the car which will always be being heated by your body heat and the light enetring the car. this is why there is a light sensor either on the dash top or behind the rearview mirror and a second in the car, usually on the air con head unit.

In the car now checking & the vent temperature is 2C with AC on, so no problem there. I was probably fooling myself as it wasn't that warm in the car when I tried it before. In the sun today th AC has certainly cooled the interior nicely.

Excellent news - at least you don't need a regas and aren't having to argue with the supplying dealer over a fault.

If the external temperature is below a certain point (don't know how low) the aircon won't work even though the ligt is on to say its working. This is so it doesn't ice itself up and damage the aircon system.

Rumour has it that it is about 5^oC

Its either 2 or 5 degrees C. Prevents the refrigerant from over condensing which would give an evaporating temperature of well below 0 degrees C.

The air temperature out of the vents will always be related to the air temperature in the cabin or outdoor air depending on whether or not the recirc is on.

As a general rule, there will be a 10-15 degree 'Delta T' across the evaporator coil, this is of course affected by fan speed, lower speeds will result in colder air from the vents. If the air coming into the car is 30 degrees C you will have an 'air off' temperature of something like 15 degrees C. Bear this in mind when testing the temperature from the vents. This rule applies when the system is set to low and full fan speed.

The A/C compressor on the Mk2 Octavia technically runs all the time, when the A/C is set to off or 'ECON' the compressor is still pumping refrigerant at a rate of around 2% maximum capacity. This allows the oil contained in the refrigerant system to circulate keeping the compressor shaft seal oiled and gas tight. This means they are much more resistant to leaks than the old clutch type compressors that can leak when the shaft seal dries out. It also means there is less stress on the compressor as it doesn't keep starting and stopping suddenly.

If your system is regassed, it may well need an oil top up, if the system springs a gas leak it will also lose some oil. A lack of oil in the compressor will drastically shorten its lifespan. This is all too often overlooked after a gas leak. The system filter-drier should also be replaced after any repair where the system has been exposed to atmosphere due to it's Hygroscopic nature.

I also believe the compressor's capacity varies depending on system demand. It duty cycles according to the demands of the climate control unit. It also holds off the compressor if the engine starts to overheat. Some cars also disengage the compressor under WOT to enable 100% of engine power to the wheels.

The sensor on the dash monitors solar loading on the car, this looks for the levels of IR radiation coming into the car and offsets the setpoint and/or fan speed accordingly - usually only applies to climatronic set to auto.

There is also a limit to the temperature setting differential on the 2 zone climatronic system, I think it might be something like 7 degrees C max differential. Any higher than that and the system cannot cope with the difference.

Set the system to recirc on really hot days, this will cool the car much more effectively as you aren't dragging hot humid air into the cabin, some systems will do this automatically on hot days. Fresh air is still required periodically to prevent the cabin air from becoming stale due to higher CO2 levels.

When the air conditioning has been running for a while, allow the evaporator to dry out by turning the air con off and leave the fan on high speed for a few minutes before getting out of the car, a wet evaporator is much more likely to allow microbes to multiply compared to a dry evaporator, microbes are the reason some systems smell like smelly old socks or cat pee! Most new commerical A/C systems have a 'coil dry' mode for this very reason.

The best way to quickly check the gas charge is to (carefully) feel the larger of the two refrigerant pipes in the engine bay, this is the suction gas pipe back to the compressor, when the system is running under full load, the pipe should be around 2-7 degrees C as a general rule. If it feels cold to the touch and has condensation on it, chances are the system has enough gas in it, if the pipe is not cold to the touch, it could be short of gas. A loud hissing from the evaporator when running is another sign of gas shortage.

Very informative post, dstev2000. Thanks