Trinary And 3 Relay Electric Fan Questions The 1947 Present The trinary switch only grounds the relay so it can start one fan. this isn't really needed at all. you could use the trinary switch to ground the fan trigger #2 and it will bring in the high speed relay. i recommend running both fans when the air is running. it will help keep the refrigerant pressures lower. Trinary switch closes, fan #2 comes on full speed. so the pcm and vintage air are happy and both have control over fan #2. for the ignition source, i had not used the electric fan circuit from my american autowire chassis harness and it is a "key on" ignition source so it worked perfect to utilize this formerly unused circuit.
Trinary And 3 Relay Electric Fan Questions The 1947 Present For what it's worth, i've run my dual electric fans for 2 3 years now. i've had two relay failures and one fan motor failure in the last year. i'm likely going back to the stock clutch fan set up. Most a c installations with a trinary switch will never have the fan running when you're cruising at 60 70 mph. just as it would with the a c off. in the a c system high pressure = high termperature. there is no reason to turn the fan on unless there's high temperature. if the fan runs all the time, it just wears it out that much quicker. Would like to add, that some people do not feel the need for a binary or trinary switch, feeling that the safety relief pressure valve on the compressor will protect the system, by releasing pressure, rather than using the binary, which switches system off for low or high situations, or trinary which adds the electric fan function when the ac. The benefits of using the trinary switch to control the fan rather than having the fan come on only when the a c clutch is engaged is as follows: 1. if the natural air flow from driving down the road is sufficient to cool the condenser, the radiator fan will not run (unless engine temp dictates it), which saves wear and tear on the radiator fan.
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