I had a new 3 dial AC Control unit installed about a month ago by my local Shop. The system has worked great until this morning. The Compressor was cycling on and off so I shut it down figuring that the system might have lost some freon. I got it home and checked the low side pressure and it was about 25 lbs., so I gave it a squirt to get it up to 35 LBS, but the system never came on this time. I momentarily jumped the compressor but got no cool air. I shifted the control on the dash to defrost still no cold air. Back to the shop in the morning!

Anybody got any clues of anything I should check?

Regards

Woody

Well it turns out that the Freon was low! Took about a pound and a half by weight.

The bad news is that there were no signs of dye leakage any place that could be seen. That means that it is probably the evaporator leaking. so we left it that the we would see how long we get out of this charge and then be prepared for the
PITA job of replacing it!

In the 740 where is the evaporator located? Behind and below the glove box, or further towards the center?

Regards

Woody

Put an ohmmeter across the pins on the pressure switch and see if current is passing. If so , check the wires going to it with engine on, ac on, you should have 12v on one of the wires, if not, chances are either the plug on the new climate control is loose or dirty, or you got a bum unit.

Question, how hot was it when you got that 35 lb reading and after how long running ?
--
-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '92 Ford F350 diesel dually

Out side temps in the 80's the car had been sitting for about an hour. I started it up with a 134 charge kit with a gauge on the low side only. Showed 25 LBS. I then gave it about 10 more lbs (just a slight bit. ) when I say pounds I mean low side gauge reading!

Regards
Woody

If the ambient temp is 80 deg, low side while running should be between 40-50 psi,
85 deg, 45-55, 90 deg 45-55. You're still probably about a can low.
--
-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '92 Ford F350 diesel dually