I have a 1992 W140 300SD. My A/C compressor is not turning. IN the past (1987 300SDL W126) my A/C compressor was engaged 100% of the time, except in economy mode.

I believe that my system is low, I will verify with my gauges but If I need to what pins do I jumper to bypass the low pressure switch?

Is this onthe receiver drier as on the older MBZ? I did find a 3 connector plug. Low pressure and high pressure?

Also is there another procedure to charge/top up a A/C system?

thanks in advance
Steve

Can't jump that switch as it is a variable resistor.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

ok then, how do you enage the clutch to charge the A/C system?

We charge with pressure thru the HIGH side. You could disconnect the 3 pin connector at the clutch & jump the clutch to power.
Also when the drier switch sees 40-50lbs@sqin of pressure the compressor should come on.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks I'll give it a try