Be careful... I think you may have put the ball valve in so that you stop the coolant flow? I can't tell from your picture but is the coolant returning in another place? I teed my two hoses together so that when the ball valve is closed the coolant can still flow.

On the front of the compressor, when the A/C is NOT turned on the "front middle plate" also known as the clutch will not spin. When the A/C is ON the clutch will spin with the pulley. There is an electromagnetic charge which attracts the metal plate on the clutch to the pulley and thus engages the pump of the compressor. So if your A/C is working the clutch will be spinning. That is what you look for.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

hmm. i'm not sure. it's right after the aux pump which has another hose coming out of the bottom of it. i based this on another thread here about bypassing the servo.

this reminds me - i just noticed my aux pump has been unplugged. from reading other threads, i don't really need this? i seemed to have plenty of heat.

i will check out that compressor tomorrow. thanks.

__________________
1980 300D, 128K

I'm not sure about the flow. I'd have to look. As long as the flow is flowing around the heater core back to the engine when you have the heater core closed you'll be fine.

The aux water pump not being plugged in is fine. It is mainly used to help with coolant flow at idle (for heat which you are not concerned about anyways). In cold climates like mine it is quite noticeable in the cold (below about 15F) at idle with and without the aux pump.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

Graplr, do you have pictures to post of your bypass fix? I am looking at doing the same thing.

__________________
1980 300SD (Mr. Sparkles), 1976 450SEL, 1982 300D turbo, 1989 VW Cabriolet morphing into a td cabriolet , 1997 TDI Passat, 1996 piece of Jeep,1993 F150, 1990 F250 7.3L...i think that's it, for now.

so the ac doesn't work very well. when i turn on the ac switch and look at the compressor, it doesn't seem to be doing anything different. does that mean i need a new compressor or is there something else i can check first?

__________________
1980 300D, 128K

Do you know if there is any coolant in the system? May have to take it in and have it charged...

__________________

Yeah that might be a good thing to try first. Is this something I can do myself? Does the compressor have to be removed?

__________________
1980 300D, 128K

Kentfelix, if you attempt to check the R-12 refrigerant yourself, then do more searches on this forum's archives. It's not something for the uninitiated.

Likewise for ading refrigerant.

No need to remove the compressor from the car.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD