Fast Caddie

95 LT1. Just curious since i thought i heard my fans running while going about 25mph today. may be my imagination lol

Thanks

Rice Killer87

fans come on/off due to the engine temp.,has nothing to do w/ mph.

Zepher

I believe 35mph and faster they are supposed to cut off.

I just looked at a couple of bin files, one is set to 0mph, one is 15mph and 2 are set to 65mph.

TraceZ

correct. It has nothing to do with your speed.

mattybz28

I thought they cut off after a certain speed... I thought this because when someone tries to give the excuse of having the air turned on while racing people have commented it's supposed to turn off at WOT / a certain speed and wouldn't have effected anything??

TraceZ

The A/C compressor will disengage past 2/3 throttle. The radiator fan is unafffected. Our cars have 2 fans and one comes on with the A/C. It is possible that if you have the A/C on and hit 2/3 throttle that the A/C fan may shut off as well as the compressor. I've never made an effort to see if it did, but even if it did the main cooling fan would still function if coolant temp was high enough to trigger it.

The 1 fan works on a thermostat, the other comes on with the A/C.

Joe Bellman

Is this true for all 4th gen cars? Which fan is the fan for thr A/C unit? Drivers side or passenger?

TraceZ

Hmm... I'd go start mine and tell ya, but the throttle body is torn down for a cleaning at the moment.

Birdman7389

I have to agree with Zepher on this.....

At a certain speed, your fans will turn off.

ex: on the highway, there is no need for your electric fans to be on, you get plenty of air from the movement of the car.

TraceZ

You can agree with him if you want to, but you'd be wrong.

If the motor reaches 220F the fans will turn on no matter how fast you are going. Typically at highway speed there is enough air movement through the radiator that it doesnt get that hot, so they rarely come on, but IF ti got hot enough, they would.

There is no mechanism in the PCM to completely shut off the fans a at predetermined speed.

Birdman7389

hmmm....wheres Ion (madwolf) when you need him?

Fast Caddie

Hmmm... i know the fans are entirely thermostat controlled or commanded on with the AC. The stock fans in a 95-up f-body have three relays, IIRC. One for low speed (of both fans), one for high speed, and one for when the AC is turned on. The pre-95s are set up where the fans have only one speed.... under light cooling needs, one fan is turned on. When higher temps are hit, the other fan is turned on also. i remember this much about them.

But, I thought i saw somewhere that when a certain speed is reached, the entire circuit is cut off so the fans won't be running at highway speeds. Could be mistaken though.

Shoebox? Madwolf?

shoebox

If the a/c head pressures reach a certain threshold the fans will turn off above a certain speed. I don't think the a/c pressure criteria overrides engine temp criteria.

TraceZ

So, when the motor gets hot, it will turn on the cooling fan no matter how fast you are going.

I had no idea that the A/C fan would turn off at speed if it had a certain head pressure. Live and learn.


so, the A/C fan can turn off at speed, but the other one will not be affected. It looks like we were all sorta right, and sorta wrong!?

Thanks Rob

MasterEvilAce

Umm.. Can someone tell me why MECHANICAL fans disengage at high speeds, and these electric ones "don't"?

Where the hell is the logic behind this? Electric fans would be easier to turn off (electrical means vs mechanical), so why wouldn't they?

It only makes sense that they'd shut off. at high speeds, the wind could turn the electric fans faster than they would turn normally, when on... so the fans should just freewheel. You don' need them at that point.