You have lost the charge, most likely. Major leak points on converted systems are any o-ring not replaced (they deteriorate after conversion, whether from the oil or the R134a I don't know), leaky evaporator (not common in the W126, overly familar to W124 owners), bad hose to compressor seals, and eroded seals between the aluminum hose manifold and the actual pump.

I've had all of these, and am still chasing down the leak on the TE after 5 years, darn it!

Look for oil on the hoses -- oil is a resul of a leak. Most 0-rings are fairly easy to replace, you can get the correct green ones at any parts store these days cheap.

However, if you do not have a good vacuum pump and a reliable set of gauges, you won't be able to fix this correctly and run the risk of wrecking a pump, and that can mean replacing the evaporator and condesor to get rid of the debris.

Follow Larry's advise, he knows what he is doing!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!