Used ls1 fans + allens 3 relay harness - and only one fan is coming on when the a/c is on, and it cycles on for about 5sec then off for 10sec.....drove around and got it up to temp, but I haven't seen the other fan come on at all. And now I can't get the stpuid things unplugged to start troubleshooting! The tab for the connector is under a plastic peice of the fan!

When should both fans be coming on? Is the cycling of the one fan when the a/c is on normal?

 

ok, got it unplugged and tested with jumper wires....the fan is working......so now I'm thinking the pcm connection isn't working. Directions said to lube up the pin - would the grease I used affect the connection?

 

I don't know about the cycling, but only one fan comes on when I turn on my ac. I think that's the way it's supposed to be. I won't be able to see if it cycles or not until tomorrow. On the grease, I used an electrical grease.

When I first installed the plug into the stock harness, I didn't push it in far enough and it didn't work. I then got it pushed in right and it started working properly.

 

PCM OUTPUT= both fans low.
AC ON = passenger side fan high
PCM and AC on = Both fans High.

It was a PITA getting the PCM wire in for me. I was able to test everything with HP Tuners. You can force the fans on and off with it. Just idling in the garage my truck never got warm enough to turn the fans on until I turned off the AC.

 

The A/C compressor clutch circuit turns on and off like that - sounds normal.

Fan control should work just as KySilverado indicated. Make sure you got that wire into the PCM all the way AND that it is in the right pin hole (blue 42). You can always test it by having the engine running and applying ground to that wire.

 

Yeah, I thought mine was messed up too because it was doing the same thing but I drove it hard, parked, and opened the hood and they were both running. That pin was a PITA for me too, when I would try to push it in the wire would just bend and I couldn't get any force to push it through. It did go through for me though and everything works fine, but I didn't lube the pin up either so I don't think it would make that much difference.

 

I didnt actually drive mine hard, just around the block, but it got up to 195 or so, shouldn't the fans come on by then?

 

They should, it just depends on what your on/off temps are in your PCM. I have a 180* stat and told him to set the temps to work with the stat and they come on before 195*. If you have the stock stat then you might want to check your tune and see what the temps were. I know with the Nelson tune he sets them to turn on with a 160* stat but if you actually get the fans and don't have a 160* stat then you have to get a retune to run them with a 180* or stock stat.

 

Talked to allen, turns out the pcm fan controls are not turned on. He's sending me another pcm (I need HPTuners! ) So I rigged up a grounding switch in the engine bay so I can turn them on between runs on the dyno tomarrow

BTW, it seems like a large area of the radiator is covered up by the ls1 fans.....would it be worthwhile to cut some holes in the plastic?

 

Yeah, most of the radiator is covered. I don't think it would make too much of a difference if you cut holes in the shroud, but I guess it might.