I have a 1997 E300D....The a/c has always blown cold however it recently stopped blowing cold and only ambient temp. is obtained through the vents. The compressor runs when system is on The clutch turns freely when spun by hand. Within the last year however the system developed a high piercing whistle through the vents. The higher the fan switch the louder the whistle. The ambient pressure on an 82 deg. day reads around 85 psi with engine OFF on the low side . With engine on and fan and a/c on max. the pressure drops to about 73 psi with engine above IDLE. The high side is around 210 psi. Looking at the various charts on the web it shows if LOW side is HIGH and High side is LOW the compressor is probably bad. However all of the charts show HIGH side around 100 psi for this condition none show my situation of 73 psi low side and 210 psi high side any one who can shed some light on this please respond.

THANKS Rod