ETR on W126 and multimeter continuity check
 

I ordered an ETR from our host. It did a continuity test on it. It showed that the relay/sensor is opened. Is this correct? Should the sensor/relay be closed in order for the a/c to work properly.

Thanks,

John

bump
 

Anybody?

OK, I have to ask this. What is an ETR?

Etr
 

Evaporator temp relay/sensor.

John

The ETR shuts the compressor off to keep the evaporator from freezing up with ice. ( Possible, but rare ) So if by open you mean current is flowing throught the ETR then that means it's allowing the compressor to run. By closed if you mean no current is flowing through the ETR then at closed it would have the compressor shut off. I forget what temp it is that it should shut the compressor off at but it is before freezing. Try your test at room temp and then after the ETR has been in your freezer 10-15 mins. You should see opposite results if it's working.

I'm not an expert, but I hope this helps.

If the evaporator freezes up because of ice then it needs to be properly evacuated to get all moisture out and recharged with R12/R134a. Refigerants are a fluid or a gas at A/C temperatures and pressures.

Water freezes, freon doesn't.

The ETR keeps water condensate from freezing over the OUTSIDE of the evaporator. This has NOTHING to do with any moisture in the closed refrigerant system. Different problem.

Thanks, that makes perfect sense.