My ac low pressure side issues?? 83 240d
 

My ac is acting up after adding a new compressor and drier. High side is showing 150 and low side 13 my mechanics says. Well he says -13. I put my gauges on it and low side shows no pressure on low side? I can't seem to find any leaks . Is it possible there is a blockage? I am confused

Sounds like a blockage if it is going to -13. First would be the expansion valve and then then the receiver drier. I'd start with replacing the expansion valve, receiver drier and a flush of the components while it is open. Then evacuate and recharge.

After sitting a day to equalize, both sides should read ~70 psig on a 70 F day. Is the evaporator icing up? My 300D have an anti-ice switch stuck into the evaporator, which opens the circuit to disable the AC clutch. Often in fails open to disable all AC, but yours might be stuck closed. Does the AC clutch cycle? Your high pressure reading is low, especially if blockage. Might be low on refrigerant. Indeed, in my 300D, the low-pressure switch at the filter-drier would disable the AC clutch if <10 psig or so.

I replaced the parts mentioned above..temp, pressure switches and drier and expansion valve. Seems to be working well so far. Now, the blower switch knob seems to be stuck?? Will not go to high speed. Is there a cable connected to that blower knob?

If it is the push button unit, no cables. Electrical controls very rarely use cables.

Manual climate control with the 3 knows. 83 240d

Knobs

Still should be all wiring; sans, cables for the blower speed control switch.

I found out there is a cable from behind the knob that goes to the heater box.

The fan switch on these manual W123 heat-AC setups also has a vent cable control that runs from the fan switch to an air flap in the duct behind the glovebox. The cable often gums-up after so many years, making the fan-switch very hard to turn. If you keep forcing it, eventually it can break the pot-metal shaft the fan-switch knob sets on. Then you'll need another fan-switch, as well as freeing up or replacing that cable.

To free up the cable, you need get behind the fan-switch to disengage the cable-coupling and also disconnect the cable at the flap behind the glovebox. Then liberally squirt automatic transmission fluid at the ends where the cable slides into the sheath. You'll also need to pull the cable ends back & forth with a needle-nose pliers numerous times until it frees-up.
After you remove the knobs, three cups, nuts and faceplate for the rotary controls, getting at the rotary fan-switch/cable coupling will still be tough as it's secured behind a plastic plate bonded to the heat-AC box. Unless a PO cut this plate, you'll probably wind up pulling the center console for enough room to get at it.
You may try disconnecting and lubing the cable behind the glovebox first to see if it will loosen enough to avoid pulling

I copied this from another forum

Didn't know...yes to ATF to the binding cable.

W123 240D AC Cable
 

Did this work out okay for you ? .

Mine was snapped off when I bought the car long ago, last Summer I searched junkyards until I found a good used cable and the plastic parts around the control knobs that were also broken or cracked .

There's also a vacuum pod behind the glove box that controls the recirculating or fresh air, this is usually perished, replacing it isn't terribly hard .

M-B sold me the new pod, it had the wrong arm on it and I was able to take the pod apart and swap the arm onto the new diaphragm .

I'm always interested in hearing about 240D HVAC issues, repairs, tips and tricks .