Hi all you benzers!
I have read all the A/C related threads before posting just in case this was a FAQ, cause I hate when folks are lazy. Anyway....

W123 1985 300D turbo sedan (Uhh, it's white, Ray)
A/C converted to 134a correctly with flush, replaced parts, new aux coolant pump, new aux fan, brand new compressor, etc. Worked ok last summer, but now the system acts really weird after recharging. Only blows cold when the temp dial is set to full cold click-stop. I have a second climate control pushbutton unit to test with, same problem. When I pull it off the clickstop it blows hot air. Replaced monovalve plunger, brand new temp control unit, nada.

The linkage on the center pod did fall off so I have a freely moving flapping center vent flap. Have not tested the vacuum system completely, but am going to pull the dash to replace all the diaphragms, center flap linkage, and clean out the evaporator core for it's 20 year anniversary. I will test the vacuum lines then, but it's probably not a vacuum problem is it? Could it have something to do with the temp sensor in the center of the dash going ka-fluey? I was also going to test that with a my multimeter, the manual says its a thermistor, different temps are supposed to give different resistance values. I appreciate any ideas you might have on this. I do plan to take complete photos of the dash removal to illustrate the procedure for all those who will follow in my footsteps, and will have BC post that for all somewhere, as I could not find a good illustrated dash removal procedure.

I am also considering replacing the (original) evaporator valve when I pull the dash, as I have heard it can be problematic in the 134 switchover, plus gets crud in it.

***SHAMELESS PLUG***
My A/C mechanic is a genius by the way, I was really lucky to have found him, a 3rd generation auto A/C specialist, his grandfather started the shop he owns/runs in Flint, Michigan, Colberg Radiator. Consistently undercharges me, even after scolding me for putting in HC 134 one time, only nicked me $30 to evacuate and refill the system!
***END OF SHAMELESS PLUG***

Thanks to everyone for all the excellent info sharing that goes on at this board! Often dealers are clueless on the older vehicles. Great resource for old Benz owners. Too bad MBZ.ORG is offline, but it might be back someday Rusty tells me... :-(

Regards,

Theo

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The dog always knows when Theo's home!