alexandervdr

I am a bit confused about how it all works on installing the AC on my 64. The wiring diagram shows how the electric fan (on the condensor) is powered through a relay activated by the trinary switch on the drier (blue line). But then it has a 2nd activation line (white) initiated by the temperature of the engine (through an engine temp switch at 190°) . Why does the condensor need more cooling depending on the temperature of the cooling water?

mdyearmike

The trinary switch turns on the fan when the a/c kicks on even if the engine is not up to temp where the engine temp sender would kick on. It also serves as a pressure switch safety for the system. You must still use the engine temp sender to control the fan when the a/c is off

alexandervdr

I understand the part about the trinary switch, but don't understand why the CONDENSOR should be cooled more (with the electric fan) if the ENGINE temperature is rising above a certain level say 190°.

kingwoodvette

I believe that the a/c system (condenser) only needs the auxiliary fan when the pressure gets too high. The coolant temp is just an added benefit for the trinary switch in that it will turn on the cooling fan when temp is above 190. I'm not sure if it is activated when the AC is not turned on. Bottom line is with the added heat into the coolant system when running the AC you may need the fan even though the AC system pressure is not high enough to call for it.

Bottom line the switch protects both engine and AC.