I haven't started my engine in a few weeks, since I rewired in the Air Pump relay I took out when I first put in my modified harness. Got rid of the error code and then it has sat since then. I started it up tonight and let it run but my fans never kicked on. I have power through the fan fuse. The temp gage didn't go above the first line (not counting the 160 line). I let it run a bit but shut it down because it seems like the fans should kick on at some point. It was 70 degrees so not like it was cold out. I've got an aluminum radiator and I built a cowl with 2, 7-inch fans I wired into the original fan leads. Before I put the air pump relay back in the fans came on very soon after start-up but I think that was a result of the error code.

At what temp should the fans come on? I'm wondering if my aluminum rad is keeping it cool enough without the fans but it was getting pretty hot to the touch.

 

There are two fan operating systems:

1993-early 1994 (2 relay system)

Fan #1 on at 226°F, Fan #2 on at 235°F


late 1994-1997 (3 relay system)

Both fans on low speed at 226°F, both fans to high speed at 235°F


Fan system wiring/control diagram:

http://shbox.com/1/fan_schematic_1995.jpg

The lines on the coolant temp gauge are roughly 160 - 185 - 210 - 235 - 260. The engine is designed by the factory to run at 210°F. Provides a balance of minimum emissions and good fuel economy.

 

Fred nailed the answer (as always), but if you ever need more info...Cooling System Operation and Testing

 

Great info as always. I'll jumper the DLC tonight and see if fans work. The aluminum radiator I'm using is thick and may just be keeping it cool enough that the fans aren't kicking on. As I stated, the gauge reads at the first line. Early on in running the engine, I did see temps higher, so I don't know why not now.

 

put the jumper on and fans came right on. I'm excited about that since my current ride, a carbureted, 350 small-block powered '39 Chevy has always had cooling issues. It'll be great if my '48 LT1-pwered ride stays cool. When I re-do the '39 next year I plan on switching to an aluminum radiator in that as well.

 

IIRC, unplugging the temp sensor on water pump will cause both fans to turn on after engine start. For test purpose to see if the fans work.