My wife owns a 96 C220. The compressor recently had the dreaded black death syndrome and needed replacement. I replaced the compressor, the receiver dryer and the expansion valve. I flushed and vacuumed the system.

I went to add freon (AC On Max..etc)..the clutch kicks on..freon is taken into the system (the pressure on the low side climbs)...then..it stops taking freon in..the pressure stabilizes (really high) but the compressor stays engaged.

The auxiliary fans DO NOT engage. The car inside temperature is 101 degrees.

I ran diagnosis via the CCU and cleared the codes...vacuumed the system and tried again..same result.

I ran diagnosis again..no codes..reset the CCU...same result.

Could the system be stuck somewhere?

Did I buy a bad compressor?

Any information is deemed helpful. Houston weather really sucks right now for no AC.

Much appreciated

The compressor must engage and fill with 3 to 4 cans of R134a (35 psi at 2k rpms low side with compressor engaged) before you can diagnose the Aux fans, or short the drier sensor to see if they kick on. If they dont check strip fuse on the fire wall or the resistor to the fans on the fenderwell.

You may have a restriction.

I don't know where your pressure sending unit is, but on my '96 E, it's after the dryer. Debris in the dryer causing a restriction will fool the computer into thinking there is not as much high-side pressure. That causes three effects: insufficient cooling, no auxiliary fan, and venting of refrigerant from the compressor relief valve.

I notice that you did not replace the condenser. That's a possible cause. You can't really flush a parallel-flow condenser and have any hope at all of getting it clean.

Forgive my ignorance, but please define "dreaded black death syndrome."

Thanks,
Rob

__________________
Robert Fini

'12 ML350 BlueTec, 87k
'06 E320CDI, 270k
'05 T1N Sprinter 2500/Pleasure-Way Plateau TS, 69k
'97 C36AMG, 313k (son's)
'94 E320T, 249k
'93 190E Sportline LE, 168k (daughter's)
'84 190E-2.3/5spd (Stage Rally Racer)
'66 230 W110 Sedan (Barn Find, Vintage Racer build in progress)

black death: http://www.aircondition.com/dsmobileac/blackdeath.html

I will examine the condenser and possibly replace it with a working model to see if that cures the problem.

Thanks for the information

Youll pull a condensor before making sure the system has charged correctly with no moisture in it?


Thats a rough road there I would slow down, not too many condensers have issues its usually the driers when they run out of dessicant in it due to leaks and moisture getting into the system.

the drier is new though...

any other thoughts?