Thanks slk230red! The aux fan does work for temp control and not the high side pressure. Just as you described. Is the high pressure switch easily replaceable? My understanding is you have to drain the system before replacing the switch. What do you know about that? I have read where someone tried to replace it and they sent all the freon into the atmosphere!

Are you still using R12?

With the engine running with the ac on, will the aux. fan operate if you short the 2 wires at the switch on the drier? This will verify that the aux. fan wiring circuit is good.

Yes, you have to evacuate the refrigerant, replace the switch, vacuum the system, and recharge. While you're at it, you might want to replace the drier/receiver and replace both switches.


Option 2: Some guys have used the aux. fan switch connector at the drier/receiver to install a manual switch inside the car to operate the aux. fan when needed. Something you could do until your a/c need other repairs, then you could replace the pressure switch at that time. Just a thought.

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Actually using R12A. It's something I found on Amazon, didn't require a retrofit and seems to work better than r134 which, according to my mechanic, doesn't cool as well and makes the system work harder. AC works great when I'm not idling. I did read that R12a is pretty flammable. More than r134 or R12.

As I just had the compressor and receiver/drier and r12a replaced, can the mechanic put back the freon after its purged or do I need to get more?

Thanks!!! Appreciate your time!