Hi,

We hit 115F in Phoenix, AZ here the last few days, and my AC stops blwoing cold when I am on the highway. The blower continues to blow, but warm. Seems that the compressor is cutting out at speeds above 50mph. As soon as I get off the freeway, the AC starts to blow ice cold. I was on the surface streets for another 25 minutes, and AC worked great. But when I got back on the freeway the compressor runs intermittently. The AC was charged last month as well so I know refrigerant issue. Could it be possible that when its very very hot outside the compressor is made to turn on by the engine management computer? Please advise if you have any info on this.

Thanks for reading!

1996 960 , 106,000 miles

Gondar,

Being overcharged might just be the problem. When its very hot out, the line to the condenser seems warm, and the return line is very cold. This is opposite of what it should be if the system is charged just right. Generally, the return line is the warmer one. Comments?

Thanks,

Azeez.

I had the same problem on my '96 960. It wasn't relative to the outside temperature, but after a few minutes of highway driving, it would start to blow warm air. At lower speeds, the cold air would return. The problem for mine was low refrigerant. A half a can solved them problem.

Are you running it on fresh or recirculating air?
At 115 outside in the shade (which equals around 120-125 in direct sun out there) it's going to have a heck of a time trying to keep up on fresh with that temp air blowing across the coils at speed.
--
-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel

Not sure if this is the only solution, but we installed a Nartron variable orifice tube on our 95 960 when we had similiar problems to yours. As the pressure in the system builds when the engine is under load, a fixed width orifice tube simply can't handle the flow of refrigerant and warm air blows. With the variable orifice tube, as pressure builds, the tube can respond and allow greater flow keeping the tempwerature consistent. This would be my thought FWIW. - Good luck with it!

It might be slightly overcharged or condensing poorly and cutting out due to high (overly) head pressure. I don't know but I'm guessing these is a HP cutout at abt 300psi.