Mercedes Benz repair: 1984 380sl AC & Vents, hand vacuum pump, vacuum controls

Question
Hello Gary

I have a 1984 380SL - the heat works well, but the ac isn't cold.  Also, the center vents do not open, but heat and outside temp air blows through all the other vents just fine.  I could never afford the repair bill - the last mechanic told me w/o even looking at the car that it would cost me between 2-3K - so I'm attempting to do it myself.  I looked throughout the Internet and learned to replace the Mono Valve which the rubber portion was torn.  I then had the car filled with freon and the AC worked - cold air!  However, I tried it again two weeks later and no cold air again.

Also, for the vents, I removed the glove box to discover a hose was disconnected.  So I connected it with a new rubber hose piece.  I also checked the diaphragms in the two actuators that were behind the glove box and they were fine.  The vents still didn't open.  Although, I did open them slightly - manually.

Do you have any suggestions as to why the ac is no longer cold?  Could it be that there is a slight leak in the system?  I didn't have any liquid under my car at all these last two weeks.

The vents - should I check the diaphragm in the actuator thats between the ignition and radio?  It seems like a dual actuator and it may be the one that controls the permafrost vent which is always on regarless of what setting I have the climate control on.

I'd really appreciate any suggestions you may have.

Thank you

Katheryn  

Answer
get a 134 conversion kit and some ac stop leak and read.  its simple install, you have a leak, freon evaporates at our pressure. use a squirt bottle with soapy water to look for freon leaks as far as vacuum controls goes, its probably just a switch. find a hand vacuum pump see if you can pump the valves open.