Vintage Air Gen IV Wiring Question

[ItDoRun]

I'm finalizing all my wiring so I can turn the key (finally!!!) and have a question on the VA wiring. My PRC electric fan wiring diagram show that the "12V ignition" wire coming from the relays needs to obviously go to an ignition source (which I've located) AND the "A/C Thermo Switch". I assume it's the blue wire coming off the A/C compressor relay but am not sure. Anybody know?

[Vega$69]

There are a couple ways to get the fans to turn on with the ac. The best way is a trinary switch on the AC dryer. It replaces the binary switch that comes with the VA system

[ItDoRun]

Originally Posted by Vega$69

There are a couple ways to get the fans to turn on with the ac. The best way is a trinary switch on the AC dryer. It replaces the binary switch that comes with the VA system

I should have been clearer in my post. I'm using the VA trinary switch. So I have a wire from the compressor to the trinary switch, a ground, a wire from the trinary switch that ties into Fan 1 which is controlled by the ECM, and the wire in question is from the trinary switch to the AC Thermostat as stated in the PRC radiator instructions. The only wire left in the VA harness is the blue wire so I assume that's the feed to/from the ac thermostat?????

The "key on" ignition source for my electric fans is also supposed to tie into the ac thermostat switch as well. It's probably staring me in the face but I see nothing in the VA instructions about this ac switch.

[snappytravis]

Originally Posted by ItDoRun

I should have been clearer in my post. I'm using the VA trinary switch. So I have a wire from the compressor to the trinary switch, a ground, a wire from the trinary switch that ties into Fan 1 which is controlled by the ECM, and the wire in question is from the trinary switch to the AC Thermostat as stated in the PRC radiator instructions. The only wire left in the VA harness is the blue wire so I assume that's the feed to/from the ac thermostat?????

The "key on" ignition source for my electric fans is also supposed to tie into the ac thermostat switch as well. It's probably staring me in the face but I see nothing in the VA instructions about this ac switch.

Just found this on the internet, Don't know if this will help you or not, but it's worth a shot. I get screwed up on wiring sometimes and start all over with each wire where it goes.

[ItDoRun]

Originally Posted by snappytravis

Just found this on the internet, Don't know if this will help you or not, but it's worth a shot. I get screwed up on wiring sometimes and start all over with each wire where it goes.

I saw that but after calling VA they said the trinary switch doesn't need to be grounded and to route the ground wire that I installed per instructions to a 12V ignition source. This makes no sense because I have a violet wire that is tied into a key on source per their wiring diagram.

[Vega$69]

Originally Posted by ItDoRun

I saw that but after calling VA they said the trinary switch doesn't need to be grounded and to route the ground wire that I installed per instructions to a 12V ignition source. This makes no sense because I have a violet wire that is tied into a key on source per their wiring diagram.

Mine is per the diagram and works perfect.

[dontlifttoshift]

I answer trinary switch questions at least once a week. Most of the confusion comes from the fact that all of the aftermarket controllers want a 12v feed to the fan controller. The theory being that most people will just tie it to the wire that turns the compressor on. But we are smarter than that, we know the fan doesn't need to run when we are doing 70 mph down the freeway.

So there are 4 wires on the trinary switch. It is important to note that it is just a pressure switch, it is not magic.

The 2 black/green wires are for the hi/low safety shutoff. If pressure is too high or low, the contacts open and the compressor shuts off. One wire goes to the compressor and the other wire goes to the ECM (genIV) or the thermostat (genII)

The 2 blue wires are for the fan control function of the trinary switch. If your fan was just wired with a simple relay, not a controller, you would ground one of these wires and the other would go to the "85" or "86" terminal of the relay. When pressure reaches 254 psi the contacts close, creating a ground path for the coil side of the relay and the fan runs.

When using a fan controller that needs a 12v signal to turn on we need to use the fan control function of the trinary switch to switch the power side instead of the ground side. Remember, it is just a switch, it doesn't care. So with a fan controller, one blue wire hooks to switched 12v and the other side to the "AC" input on your controller. Now when pressure reaches 254 psi, the contacts close and send a 12v signal to the fan controller and the fans turn on. The only thing that this 12v wire does is tell the controller that we need the fans on.

I typically run both blue wires from the fan switch to the fan controller and get the switched 12v from there.

[ItDoRun]

Originally Posted by Vega$69

Mine is per the diagram and works perfect.

let me make sure I'm clear. I have a black/green wire from trinary switch to compressor, a blue wire to a chassis ground, a black/green wire from trinary switch to the a/c compressor relay in the VA wiring harness, and a blue wire from trinary switch to the Fan 1 relay. Does that sound right?

[ItDoRun]

I had it right to begin with. Thanks for the input everyone

[snappytravis]

Originally Posted by ItDoRun

I had it right to begin with. Thanks for the input everyone

lol,, Glad I am not the only guy that does stuff like that. Overthinking,, These cars will drive a guy nuts..Good luck