On the installs where the trinary switch is needed, we are using a switch from a A/C hose rebuilder. It has a low pressure and a high pressure switch for the fan built into one. It has 3 functions.
1. Turn off the compressor if you have refrigerant loss
2. Turn off the compressor if you have and overpressure situation
3. Turn on the aux fan at over 225psi.

This will take out the old style temp regulation of the aux fan. In 134 systems, the pressure may build faster than the temp.

------------------
Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM