Air Conditioner Puzzle

[BAR]

Now I am puzzled. The aicon on my 450SE works [blows cold] when the car is at idle: when driving along it seems to 'turn off' and gets down to outside air temp very quickly.

The fan belt appears to be correctly tensioned.

Any suggestions as to what is the problem?

 

[BenzBoy]

I had similar and it was the T valve. No guarantee it is that though without testing. Is the system fully charged with gas?
Regards,
Benz-Boy

 

[Styria]

Sorry Bar, I don't have one iota of a clue - all I can say is to get your level of gas re-checked. I don't know who you're using, but there is a good, AND experienced guy, at Glenhaven that I use. Regards Styria

 

[John S]

There are two things that happen at idle that change when you start driving, vacuum and water flow.

The vacuum available at idle is the highest it's going to be, and the hot water flow is the lowest. When you drive off there is reduction in vacuum available, and the water flow increases. If the hot water valve is not shutting enough it may be fighting your air conditioning. Just a thought.

 

[BAR]

Thanks guys. I have had it regassed recently.

The heater valve is properly closed and there is plenty of vacuum.

Looks like the T-valve suggestion if best idea. Where is it located?

 

[John S]

I saw a similar problem on another site for a Diesel exhibiting the same symptoms, he was told to check the monovalve, probably a ruptured diaphragm.