I installed a set of LT1 fans last night.I used a hayden thermo switch and 2 relays.Everything works as it should but there is one problem.If I cut the truck off while the fans are running,everything continues to run for several seconds after the key is off,even the engine.If the fans arent running,everything powers down as normal.I ran my 12v "ignition on" wire to the fuse box,tied into the circuit that has a 25 amp fuse labeled b/u lp.
Any ideas on what could be causing this???

 

The fans will continue to run until the thermostat reaches the on/off point you've selected.If you switch your power wire to a ignition switched source the fans would turn off when you turn off the ignition.

 

I just ran my fans to a switched ACC fuse in the panel for the switched wire. I believe it was yellow.

Constant comes from the battery, green wire to A/C clutch is used as a manual switch. The fans ALWAYS on with the A/C compressor made me lug a bit more down the freeway that I was expecting hence hurting my gas milage some. Now if I go really slow (under 30MPH) I just flip the switch...but it has been so hot here that they pretty much stay on any driving except on the freeway.

 

The circuit I am running too is only hot when the ignition is on.The fans running isn't my problem,everything continues to run.I can pull the key out of the ignition and the engine is still running for several seconds.It only does this when the fans are on,the engine shuts right off if the fans are not on.It seems like when the fans are on,it doesnt want to shut down that circuit.But with the key off,how can that be?

 

I figured it out.....I had my constant 12v and ignition on 12v wires backwards
It's working right and cutting off like it should now

 

Hehe, I knew you had some backwards wiring...