With the heat on 'Auto low', I can hear the AC compressing cycling on my 79SD. Is this normal? I'm aware that often times the AC will work on the defrost mode but I am surprised to hear the compressor kicking on and off in the heat mode. The AC switch is off. This is the system with the servo. Servo was replaced prior to my purchasing the car.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

On my w123, the compressor cycles when it is cold out, in all modes except ECON. It cycles less as the ambient temp rises.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I think that on the Evil Servo systems the compressor is on all the time. It was later on that you were able to cut it off with the 'econ' mode. They made it work to dehumidify the air whether it was cooling or heating.

I could be wrong, but I don't think so

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"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
Monika '74 450 SL
BrownHilda '79 280SL
FoxyCleopatra '99 Chevy Suburban
Scarlett 2014 Jeep Cherokee
Krystal 2004 Volvo S60
Gone
'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
Fritzi '84 BMW
'92 Subaru
'96 Impala SS
'71 Buick GS conv
'67 GTO conv
'63 Corvair conv
'57 Nomad

I second LUVMB. The compressor is always on even when you choose Heat.

- bigmaq

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2009 R350, now the daily driver
1980 300SD, was the daily driver