[homemade87]

Heres what I have experienced with out the trinary. This is on a 82 c10. I am using the 82 controls to turn the a/c clutch on. My 04 pcm is a serial data signal and no way to use it with out the bcm. I am also using the 82 low pressure switch for the compressor cut out. This seems to work fine.

For the fans, I am running a dual fan set up with the factory three relay. This allows the low speed to run the two fans in parallel with good air flow and runs a lot quieter. What the high pressure trinay switch will do in monitor the high pressure from the compressor. When it sees what it needs it will turn the low speed on ( each fan on at 50% at the same time ). If the head pressure gets to high it will turn the high speed on ( both fans on at 100%) until pressure is dropped. If the trinary is not used my only option is to turn the fans on at high speed at all times. I have found out that at start up if a/c is on, the compressor and fans (high speed) are coming on at the same time and the engine will drag hard ( almost stall) for a few seconds trying to catch up getting the alternator and comp going. With the trinary the fan will not come on untill it sees pressure there for a delay at start up for the fans.
The fans dont always need to run on high, this way the computor knows what to do.

Also another benefit from this is fuel economy. Gm has designed it so the fans will shut off at about 35 to 40mph for engine and a/c. If by chance the pressure in the system gets to high it will cut it back on to control it. With both fans on high at all times iit really drags the alternator down there for lower fuel econony.

This is the way gm had intended for this system to work. This is nothing I had dreamed up.The only real difference in what I am doing is I can not use the pcm for a/c request because of the serial data signal and shut the compressor off if the pressure gets to high. I have been running it this way with out the trinary for some time with out any problem. I suspect that most are without a high pressure cut out. Once I get things together I may look into adding a relay to the trinay and run the comp clutch thru it to shut it of in case too high pressure.

I have got everything I need to try to braze a fitting in today. I hope this works. If it dont, I am not sure what I am going to have to do to get it in there. I will figure something out . I was hoping someone had already figured it out and had a source for parts.


( not a great idea to have the fan automatically come on when the a comes on )

I assume the statement above was to say when the a/c ( meaning comp clutch )comes on in your post. And you are correct. With the trinay there would be almost no reason for the fan and clutch to come on at the same time. If the comp is not running there would be no signal from the trinary switch to turn the fan on. Even if the engine was shut off and restarted right quick I think the pcm has a delay and will not start the fans right away.