Re: Climate control probs and idle
I think the advice about the compressor trying to seize is right. I'd be surprised if the problem is caused by the trinary switch. Refrigerant overcharge would definately cause the compressor clutch to engage and disengage very quickly, so I suggest you check what quantity (grams) of refrigerant was used for your last recharge. Best to eliminate the simpler things first, and be sure of exactly what was done to your car. Those compressors (Sanden OEM, model type 1157 or 1158 on your car) do fail occasionally, but as with all compressors, some other factor almost always causes the failure. Usually that is a result of lack of AC system maintenance, or failure of another component.
So, find out how much refrigerant was used to charge the system, and what refrigerant type was used. There are two variations of the AC systems used on the 156. Each variation has a different refrigerant charge. Depending on the age of your car it could be fitted with either variation.
"Version 1" has a separate Receiver Drier cylinder positioned in the front/RH engine bay, ahead of the wheelarch. "Version 2" has no seperate Receiver Drier (the 'drier is incorporated in the condenser - front heat exchanger). I think the system charge for "Version 1" is 750g. I know for certain that the charge for the "Version 2" type is 500g, because that's what my car has. Also the AC system is designed specifically for use with "R134a" refrigerant.
So, a few things to check !