Automatic Air Conditioning (Climate Control)

[pikesrelaybus]

Hi, I have a another "possible" problem with my Relay. It's not a huge problem but involves the Air Conditioning. Can someone with a Relay / Jumper that has the automatic climtate control, whereby you can adjust the temperature / has digital readout check to see if they're pump clutch drops in when the temperature is reduced and disengaged when the temperature is increased. Afterall, logic prevails that you don't need to have the air con on when it's freezing cold outside and your trying to stay warm..!

 

 

On my vehicle the pump continues no matter how high the temperature is set. This isn't a huge problem as I can simply press the air-con button (has a snowflake on it), and the pump dis-engages. Note that while it's dis-engaged the temperature readout will flash if a low temperature is required, kind of a, "You need to reengage the pump if you ant that" kind of hint. There has been times during very cold night driving that no matter how hi we set the temperature only luke warm air comes through, disengage the pump and we cook..!

 

Possibly faults?, well I would definately say the fault is on the control panel and not somewhere else as the pump can be forefully engaged and disengaged via the snowflake button.. I suspect the answer will eventually come from myself but it'll be nice to confirm the normal operation before I rip my console apart. I suspect it's a faulty/short switch somewhere on the control pcb.

 

 

[paul.h]

I do not think there is anything wrong with your air conditioning system and it appears to work the same as on the cars we have had.

 

I think the way air conditioning works is the compressor (pump) when switched on is controlled by the refrigerant pressure in the system, so the compressor clutch is heard to pull in/out as the pressure falls and rises. The air flow rates through the front condenser radiator and cabin evaporator matrix affect the refrigerant pressure. The temperature only controls the hot air flap (and auto also the air flow rate/direction into the cabin). The air con compressor will not run if the cabin fan is not on, if the outside air temperature is below about 6°C, the engine load is high so the engine temperature is high. So, if you keep the cabin fan on, the heating system set to auto, your compressor will continue to run unless switched off and there appears to be nothing wrong with your system.

 

Many people run the air conditioning all the time but I prefer to use it every few weeks so the seals do not dry out, or when it is hot or when the windows steam up. This way the effect on fuel consumption is minimised and the need to disinfect the evaporator matrix to remove the wet dog smell due to mould build up is infrequent.

[pikesrelaybus]

Hmm, still not convinced. The pump should only run when it's not a) iced up and b) the tempature inside needs to be cooler than outside, just like summer conditions. If the temperature inside needs to be higher than the outside (aka Winter!) then the pump should be inhibited, otherwise it'll cool the heated air and you end up with warm'ish air, not warm/hot air. There's only one exception to the last comment in that the pump will never run in winter conditions and that would be wrong, especially in some countries, therefore I wouldn't be surprised if manufacturers make "climate control" systems run the pump regardless of setting for a set period each journey to prevent seals drying out. Mine appears to run all the time unless I hit the inhibit button of course and when it's bitterly cold outside we can't get warm unless the pump is inhibited. I remember my C3 behaving in this logical manner and I think next time I'm near my dealership I'll get them to humour me.. If anyone with a Relay that has climate control fitted could confirm this then I could start exploring further.

[paul.h]

I think trying to control the compressor on cabin temperature as well as refrigerant pressure would require a complicated control system of the compressor and temperature flaps rather than just an inhibit system. Also to dry the air (such as windows steamed up) can be required when inside the cabin is warmer than the outside so the inhibit would require an override. For now, why not just have the compressor switched off and save on fuel, some estimates are about 5% so maybe an extra 2 mpg approx £100 a year at about 10000 miles a year and 40 mpg.