need help jumping AC compressor
 

on my W124. Freon is low need to add but compressor doesn.t come on . read where compressor can be jumped but having trouble determining which 2 wires near the dryer to unplug and jump. Could someone give me some guidance on how to identify the wires to jump?
thanks

Just jump one pair and see if it comes on. If it does not jump the other pair. If it still does not come on you have other issues. Hard to describe the pressure switch from here. The other pair should make the aux fan come on.

You can also remove the compressor relay (close to the battery), and bridge pins 5 & 7.

If you are simply charging a low system, you should NOT have to jump the switch to charge. It is a low pressure switch and will make contact once there is enough refrigerant in the system to go above its pressure rating.

Simply start adding refrigerant on the low side. Even if the clutch is not engaged, it will draw enough refrigerant to engage the switch, turning on the compressor and then you can continue your charging process from there.

All that said, the problem you are facing is an empty system. Since you have an empty system, that means that you have a leak. If you have not already repaired the leak, make sure you put in some UV dye so that you can find the leak if the refrigerant leaks out.

Good luck,

What Larry says is true, I replaced my evap on my 140 and it worked just like that. Start the car, turn on the air, crank open the valve on the freon. The pressure will equalize between the cannister and the system and will click on the compressor. If it doesn't come on you could have a faulty pressure switch, which I replaced one of those too. Make sure you don't have your AC in the EC mode, a guy that evaced my system could not get it to come on and didn't know about that EC mode. Good luck!
Brian