Gen V LT4 Air Conditioning Wiring

[glamis44]

Does anyone have a way to signal the LT4 ECM to turn on one fan when the AC is turned on? The LT4 has two Electric Fan outputs that power 2 Electric Fans at different temperatures. I am looking to use those two wires and run a signal from the compressor to turn on a fan.

Thoughts?

I do not want to run a separate control if I do not have to. Has to be a way based on the factory LT4 set up....

[srode]

I don't know if you can signal the ECM, but you can use the a pressure sensor on the AC to trigger one or both fans to come on tapping into the relay(s) the ECM triggers for temperature control I think. Vintage Air a pressure sensor that triggers at two different set points so you could use one for each of the relays.

[dhutton]

A trinary switch has a set of contact specifically for running the fans when the pressure warrants it. The other set of contacts disables the compressor if the pressure is too low or too high.

Don

[srode]

A trinary switch has a set of contact specifically for running the fans when the pressure warrants it. The other set of contacts disables the compressor if the pressure is too low or too high.

Don

Better explanation, I was mistaken on the 2 pressure speeds. Here's a video explaining it from VA. I'd guess if you want to wire it so it triggers both fan relays instead of just one, that would work too even though they have separate triggers from the ECM for engine temperature and separate relays in the fuse box? https://www.youtube.com/watch?v=l604JCZx_ow

[dhutton]

Better explanation, I was mistaken on the 2 pressure speeds. Here's a video explaining it from VA. I'd guess if you want to wire it so it triggers both fan relays instead of just one, that would work too even though they have separate triggers from the ECM for engine temperature and separate relays in the fuse box? https://www.youtube.com/watch?v=l604JCZx_ow
Most guys only trigger one fan with the trinary switch.

Don