The a/c compressor on my 76 240d is not coming on and it is getting warm here.
I jumped the a/c clutch and it engages.
I charged the system and it is full although the pressure is a little low.
The line going back to the firewall gets very cold quickly.
The fuses and the relay on the passenger firewall are both working.
The blower switch works for the defrost and heat settings but the ac switch does not kick the blower up high like it did last summer.
I do seem to have continuity through the ac temp control switch.
The vacuum lines appear to be in the correct place.
I had the console out while replacing interior and carpet but everything went back where I thought I removed it from.
What am I missing? I do not see a pressure switch in the system, when I short the switch on the evaporator, the aux fan on the radiator comes on.
And want the heck is the red wire to the a/c temp control switch? It does not show up on any schematic I have seen.

I have searched but w115 a/c questions have been few and far between, it must be a good system for the most part (or everybody else gave up)
Thanks for the help.

__________________
Ncnetman
1978 300cd fresh paint
1965 Mustang
1968 Torino GT fastback
2015 VW Passat TDI
1969 Ranchero- project
1974 240d 4-speed -for sale
1976 240d - for sale
1990 6.2 Suburban 194k-getting a 6.5 turbo
2008 Duramax Silverado-totaled
1959 Chev 3100 Fleetside - sold

bump
just hoping for fresh set of eyes to look at this problem for me.

__________________
Ncnetman
1978 300cd fresh paint
1965 Mustang
1968 Torino GT fastback
2015 VW Passat TDI
1969 Ranchero- project
1974 240d 4-speed -for sale
1976 240d - for sale
1990 6.2 Suburban 194k-getting a 6.5 turbo
2008 Duramax Silverado-totaled
1959 Chev 3100 Fleetside - sold

Sorry, all my literature is for a 123....

" I do not see a pressure switch in the system, when I short the switch on the evaporator, the aux fan on the radiator comes on.
And want the heck is the red wire to the a/c temp control switch? It does not show up on any schematic I have seen."

Do you mean the switch on the Receiver/Dryer rather than the evaporator?
Do you have two switches on the plumbing at the Receiver/Dryer ?

I guess the reciever/dryer, the little rascal on the extreme passenger side firewall with the sight glass on the top.
Just one set of wires going to it. No other wires near it.

__________________
Ncnetman
1978 300cd fresh paint
1965 Mustang
1968 Torino GT fastback
2015 VW Passat TDI
1969 Ranchero- project
1974 240d 4-speed -for sale
1976 240d - for sale
1990 6.2 Suburban 194k-getting a 6.5 turbo
2008 Duramax Silverado-totaled
1959 Chev 3100 Fleetside - sold

Yes, that critter... usually there are two switches right there... one on top and one on the side.... but the low pressure cut out switch could be located anywhere the refrigerant is...
Start at the compressor and go backwards... is there a relay which is supposed to provide the electricity to the compressor clutch ?
Check for power at that relay...and check to see what sends the control current to the relay...

115 A/C is uhhh... wierd. What operates that relay is vacuum, not current.

__________________
Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



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