Discussion
Just changed an aircon pipe on my 156 that had a leak, aircon man came out and gassed her up - no leaks. WooHoo. Ish.
Aircon now works fine when you first get in the car, lovely freezing cold air. However after a while (5-10mins?) the aircon stops working and the compressor doesn't engage anymore. Its as if the aircon works fine when the engine is cold, but packs in when it gets warmed up.
If you stop the car for an hour or so then start her up, the aircon works perfectly again!
Anybody else had this problem before? Any ideas? It seems like the compressor is turning itself off after a certain time, but I've no idea why :(
Aircon now works fine when you first get in the car, lovely freezing cold air. However after a while (5-10mins?) the aircon stops working and the compressor doesn't engage anymore. Its as if the aircon works fine when the engine is cold, but packs in when it gets warmed up.
If you stop the car for an hour or so then start her up, the aircon works perfectly again!
Anybody else had this problem before? Any ideas? It seems like the compressor is turning itself off after a certain time, but I've no idea why :(
First thought is that there is too much gas in it. The systems have a three-way pressure switch which stops the compressor working when the pressure is too low OR too high. That said, I'd have thought it would take less than 10 mins to cut out.
Also maybe there is a load of moisture in the refrigerant which is freezing. The system will work fine until you get a blob of ice in the expansion valve. When that happens, the pressure in the "high" side of the system will go sky high ('cause it's effectively blocked)and the pump will cut out. As soon as the ice melts, it will be happy again for a while. Do you know if the system has a "dryer" in it and if he changed the dryer unit when the pipe was changed?
Also maybe there is a load of moisture in the refrigerant which is freezing. The system will work fine until you get a blob of ice in the expansion valve. When that happens, the pressure in the "high" side of the system will go sky high ('cause it's effectively blocked)and the pump will cut out. As soon as the ice melts, it will be happy again for a while. Do you know if the system has a "dryer" in it and if he changed the dryer unit when the pipe was changed?
YES! You could damage the compressor otherwise!
I'm only fmiliar with old R12 systems and I imagine yours is a much newer R134A system. I can't remember whether these have dryers but I think they do. It's a canister about the size of a beer can or maybe a Coke can that goes in the high pressure hose between the pump and the expansion valve. How did you re-gas it when you changed the pipe and how long were the contents open to atmosphere? Did you add oil as well as refrigerant?
I'm only fmiliar with old R12 systems and I imagine yours is a much newer R134A system. I can't remember whether these have dryers but I think they do. It's a canister about the size of a beer can or maybe a Coke can that goes in the high pressure hose between the pump and the expansion valve. How did you re-gas it when you changed the pipe and how long were the contents open to atmosphere? Did you add oil as well as refrigerant?
Just had a look at your profile. I see you've got a 156. YES it does have a dryer and it should be changed. The dryer is behind the right hand headlight. If the system has been open to atmosphere for more than about 15 minutes, it will have absorbed enough moisture to saturate the dessicant in the dryer. The oil used in the system is fiercely hygroscopic so you'll need to drain and flush the whole system, dry it out with a vacuum pump and then add the right amount of refrigerant and PAG oil (the latter from a sealed container) and change the dryer.
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