i installed 4th gen fans on my 1992 rs. i removed the a/c a while ago. when the fans come on it loads the engine down some. since i no longer have a/c i was wondering if i put the positive signal from the fans coming on to the a/c positive signal to the pcm for it to compensate for the extra load.

 

A/C compensation circuits were used because the A/C put a load on the motor from the clutch and belt, which slowed the turning of the engine by making resistance to the actual crank pulley.

YOUR issue is with an electrical load. Did you use relays so that the fans get direct battery power? If the battery is good, there's no reason why electric fans should put any load on the ignition circuitry if wired correctly.

 

 

my fans only engage when i jump them with a 12 volt power source...anyone know where the relay location is? i dont want a 10$ part to hurt my new toy

 

the electric fans will put a slight load on the engine
when they are on due to the current load on the
alternator-enough to drop the idle speed a little.
My third has a belt drive fan,but my '71 saab has
an electric fan(a little 10"one ,probably pulls less than
5 amps)when that fan comes on,it does drop the idle
a little.Third and fourth gen dual fans draw about 15a
with both fans running.

 

well since they are dual 4th gen fans and they draw more amps than the dual fans on our third gens. they draw a good amount. no matter what amperage they draw it still draws the engine down about 150 rpms. so i was wondering if going to the a/c signal will compensate. if so i will idle her down a little more.

and since they come on at 60% the draw is around 20 to 25 amps at first till they get going. then it is a lil less but still enough to draw the engine down. if the a/c signal will bump the idle 100 rpm's it would be perfect for my situation.

 

Do they connect into the alternator wiring, or get power from battery? I read sometimes where some dual fan 3rd gens had fan wiring in with the alternator wiring. I guess my thought was if they get power from the battery rather than from the alternator, then maybe wouldn't be a drain, since the alternator feeds ignition directly and charges battery indirectly, right? I mean can't you disconnect battery after car is started and it will keep running because of alternator?

 

they hook straight to the battery due to the instruction from flexalite. it is a flexalite controller which switches the ground signal to turn the fans on and off. when the target temp is reached it turns the fans on at 60%. which is still a good amount of draw. then if needed ( which never is ) it will go to 100%. all my alternator wiring and draw is correct. trust me. i am running a 6 gauge alternator wire also. the controller needs to be hooked straight to the battery since it is switching the ground side.

 

Gotcha. I too am using a Flex-a-lite controller, love that thing! But I'm just running a single stock TBI fan, so I don't have any electrical load issues.

Your idea on the A/C load switch to bump up the rpms a tad sounds good - I'm just not sure what kind of a signal the ECM gets from the high pressure switch on the A/C system to tell the ECM to do it. Maybe someone in the prom section knows. Good luck! Let us know if you find out and get it to work!

 

well according to the pinout diagram it is a battery positive signal. hoping it works. i will post when i get out there and solder it together. i also emailed tbichips since that who tuned my chip to ask. i will post the results.

 

ok took the 6 gauge wire from the battery to the alt. yes it is a 105 amp. put in a good 8 guage wire. i also hooked the a/c request wire to the ecm. now the draw is less and the idle does kick up to make up for it. works great.