$OE dual fan control

[dave w]

I think it would OK to use one PCM output (ground signal) for two individual fan relays. The PCM output could be wired to both relays, with each relay controlling one fan each.

I'm thinking I like the idea of using a 454 .bin and a 454 Memcal.

dave w

[one92rs]

reason I was asking is I have this schematic for the 4th gen fans. if you wire the fan relay #3 to a/c it will work great. with a/c signal only then only one fan comes on on high. with temp setting one reached both fans come on at about 60%. with a/c signal and temp or high temp only both fans come on at 100%. just a thought.

[Fast355]

reason I was asking is I have this schematic for the 4th gen fans. if you wire the fan relay #3 to a/c it will work great. with a/c signal only then only one fan comes on on high. with temp setting one reached both fans come on at about 60%. with a/c signal and temp or high temp only both fans come on at 100%. just a thought.

That is just asking for compressor failure in hot weather. You are better off using both fans on low with the a/c request and high speed with engine temp rise. You get more air than a single fan on high and more even cooling of the condenser. Colder a/c and less noise are both wins to me. My PCM controls the low speed on my Express with high overide coming from a F-car cylinder head mounted fan switch. My 0411 setup running the 5.7 express calibration runs 1 fan as an auxiliary. Its output turns both fans on low. The cylinder head switch bumps the fans to high. Also since I pulled my relay control power from an unused constant hot fuse under the hood if the engine is shut down hot. One cooling fan can turn on and cool the engine. With a 170*F thermostat and powerful GM truck fans it rarely hits the 200*F.