I got the relays today, but now have a question about how Nelson sets their fans to operate. I ordered the PCM from them too for a stock truck w/ stock thermostat.

The right fan comes on high when the A/C pump clicks on, but neither of the fans come on low or high any other time. I drove the truck around today and even after letting it idle after fully warmed up the fans never came on. The water temp needle still said a little under 210* though.

Maybe my stock cooling system just kicks ***?

 

What temp are your fans set to come on at? It's possible that the pin isn't fully seated into pin42 of the PCM. When you reach turn on temp both fans should come on low, if the ac is on while it reaches turn on temp both fans will come on high. AC on only = 1 fan like you already have.

 

to fully test it, let the truck get warmed up with the A/C OFF.... the one fan on high will keep it from getting to the turn on temp except for the middle of the summer when it's really hot.