Originally Posted by sixto

You have to add a dedicated temp sensor for the glow relay. The 603.960/1 didn’t come with it. Fitting one to the side of the head looked difficult so I used the threaded port on the water pump housing ahead of the thermostat. I could do this because I removed the transmission vacuum amplifier.

Temp sensor 008 542 56 17 has a pin each for gauge sender and glow relay. I can’t find the part number of the glow relay only sensor. The 603.960/1 gauge sender has only 1 pin.

If you bridge the pigtails and the fans don’t blow, it could be a bad low speed resistor behind the left headlight.

Most folks here upgrade the early 124 single fan to later dual fan. I don’t recall that anyone retrofitted a 126 single fan. I think there are multiple sizes of 126 single fan. I found it dificult to remove the 124 dual fans. Once it’s out, it can’t be that difficult to fit a single fan.

Why not wire the fan directly to the battery (fused!) with a switch for the driver? At least until you sort the sensors and wiring.

Sixto
98 E320s sedan and wagon
02 C320 wagon