w115 a/c problem

[ckbenz]

hi, i got a problem with my air condition recently, i am not sure what happened to it and i have not yet see my mechanic about it. wish you guys can give me some hints and advice.
in norlmal starting, the aircond blow fine and relatively cold but once hit the road under the hot sun( malaysia wheather is around 37 to 39 degree celcius whole year) it started to stop blowing cold and seems like blowing hot air. this problem have not occured when i got the car back in april. is my car tend to overheat or there is lost of gas in the a/c?

[psfred]

Make sure the belt is in good condition and tight, as it may slip at speed if it is loose. Will usually screech something terrible, too! This will cause adequate cooling idling, but the compressor isn't turning fast enough at speed.

There are several other possibilities, too -- do you get fog out the vents? If so, the evaporator is freezing up from a stuck expansion valve or low freon.

The thermostat can be bad, too, so that it never turns the compressor back on, and the clutch can be bad so that when it gets hot it slips.

Your mechanic will be able to tell when he attaches the gauges.

You can check for charge by looking at the sight glass (small glass window) on the top of the receiver/dryer. Its a black metal cansiter with two small hoses, back on the passenger side firewall. It must start clear with the AC off, get bubbles in it, and then go clear with only liquid showing after a few seconds of the compressor turning. If it stays foamy, it's low on charge.

Peter