Is there anyone out there with hands on experience, who could offer impartial, off-the-record, advice on a problem with the aircon on the above, which appears to be "working too well"
Thank you, petel@clara.co.uk
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I'm not sure that air-con can actually work "too well"
As winter draws on, the heater control will have to be progressively turned up to get the desired temperature. Climate control should achieve the set temperature automatically.
Maybe the climate control is not working properly.
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Thanks for the reply Roger. Do you have hands on experience of these systems please ?
Thank you, Pete.
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Pete, your name, car, and problem rings some bells with me. Have we discussed this before?
Still, if you are saying the vent temp is too low, get yourself a thermometer and take a couple of readings of the temp at the centre vent, a/c on, no heat added, medium fan speed, engine at 1500rpm, and give it a few minutes to stabilize. Temperature should be between zero and 6degC. If lower then you run the risk of the evaporator freezing up. Let me know what you find out then we can take it further.
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Hello Dave N.
Thank you for your response.
I did post on this some months ago but the thread died due to lack of response and the cars owner spending several months in the States on company business.
You are quite correct, the unit is freezing up. It seems that you have seen this problem before.
Would still welcome the chance to contact you direct on this.
Thank you, petel@clara.co.uk
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Pete, I'll respond by email, but also post here for the benefit of others.
All a/c systems need a method of maintaining evaporator temperature just above freezing point. On Vauxhalls, they use a variable displacement compressor with a valve in the back of it. This valve measures the refrigerant pressure entering the compressor suction port, and uses this pressure to determine the temp of the evap. If evap temp rises due to high demand, the valve sees a higher pressure, as temp and pressure are directly related, and increases the displacement of the compressor, thereby increasing the cooling capacity of the evap. As demand dereases, the valve in the compressor will see a drop in pressure as the evap temp drops, and will reduce the displacement of the compressor accordingly. Therefore, if evap temp is too low, ie. below zero degC, then the valve isn't doing it's job and reducing the diplacement of the pump. This is easy to diagnose by measuring the low side pressure of the system, and it should read 1.9Bar with the compressor running. If it's lower than this, and I suspect it will be, then the compressor needs replacing. The valve itself can be replaced, but I think on the V6 the compressor needs removing to get at it, and it will be just as easy to swop the whole lot, rather than just the valve, then find out the part the valve slide in is worn or doesn't seal properly.
Many more cars are now coming out with this type of compressor, as you don't have to suffer the constant cycling of the compressor that can upset cars with little engines. It's also the reason why you can leave it on all year round, as it sorts itself out regards cooling, and doesn't affect fuel consumption any.
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