Ive had the same problem for a year now. I about gave up on it and hooked a fan up to the ignition. I got two fans right. Can sombody tell me the actual way they are supposed to run. Every shop has a diffirent story. The fan on the driverside I thouht was supposed to go on with the A/C. Thats all I know.

 

The factory fan function varied by year. What year and what engine?

------------------
Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://www.ozemail.com/au/jca69/mods/williesz/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

Sorry, Im stupid. ITs a 91 Z-28 305 tpi.
right now I just got the passenger side fan wired to the ignition. It has an ADS superchip. I think thats who makes it. Isnt that supposed to turn on the fan earlier?

 

Okay, here goes. The primary fan (driver's side) turns on when

1) Engine temp rises to 223 degrees or
2) A/C is engaged and vehicle speed is over ~35 mph or
3) The ALDL diagnostic terminal is grounded.

#1 & #2 are ECM controlled.

The secondary fan turns on when

1) Engine temp rises to ~243 degrees or
2) A/C is engaged and vehicle speed is over ~35 mph.

#1 is controlled by the fan switch located in the passenger side head. #2 is ECM controlled.

If your fan(s) are not engaging as specified, the only approach is to locate the problem and fix it BEFORE any changes are made.

------------------
Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://www.ozemail.com/au/jca69/mods/williesz/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

Addendum to secondary fan #2:

The secondary fan turns on if the pressure on the A/C liquid line is above 232 psig (150 F for R-12). There is a pressure switch on the liquid line. The ECM monitors the status of the secondary cooling fan. The secondary fan should run on a very hot day with the A/C on.

Tim

 

Willie,

I think you meant to say "...and vehicle speed is under (vice over) ~35..." for both fans.

[This message has been edited by Stuart Moss (edited October 24, 2000).]

 

Thanks Stewart. It was very early this morning when I posted -- the brain wasn't functioning yet.

Willie



[This message has been edited by Willie (edited October 24, 2000).]

 

So the driver side is the primary fan? Does my chip affect its turn on point? Last time I checked the motor was still good for the fan. She ran hot as hell today in the city.

 

Yes, the driver's side is the primary fan & the on & off temperature thresholds are programmed in the PROM.

Tim