RW>TOM WALKER wrote to ROY WITT:   
      
   RW>Mine says the same thing. It even has 4 stages of procedures to check the   
   RW>AC system. However, it doesn't have a procedure to check out why the   
   RW>radiator fans don't engage as the engine temps get higher than normal   
   RW>operating temps when the PCM detects that the system is low on freon.   
      
   Since the Engine temperature function has priority so the fans should   
   have run in high speed. Since it did not it indicatas either a bad   
   engine block sensor, a problem with one of the Relays, or an unusual   
   problem with the vehicle speed input to the PCM.   
      
   RW> TW> From the service manual of a 1998 5.7L F-car (Camaro/Firebird) here   
   RW> TW> is the descriptio of the cooling fan controls   
      
   RW> TW> Engine Cooling Fan Description - Electric   
   RW> TW> The electric cooling fans are used to cool engine coolant flowing   
   RW> TW> through the radiator. The fans are also used to cool the refrigerant   
   RW> TW> flowing through the A/C condenser.   
      
   RW> TW> The electric cooling fans are controlled by the PCM. The PCM controls   
   RW> TW> the ground path for the three cooling fan relays. The relays are used   
   RW> TW> to control the high current flow to power the cooling fan motors.   
   RW> TW> Both fans operate together. When minimum cooling is required, the PCM   
   RW> TW> energizes cooling fan relay #1 and both fans operate at low speed,   
   RW> TW> since the fans are connected in series through cooling fan relay #3.   
   RW> TW> Cooling fan relay #2 is open (not energized) and is not used for low   
   RW> TW> speed operation of the fans. When maximum cooling is required, the   
   RW> TW> PCM energizes all three cooling fan relays. The left fan is still   
   RW> TW> powered through cooling fan relay #1, but is now grounded through   
   RW> TW> cooling fan relay #3. The right fan is now powered directly through   
   RW> TW> cooling fan relay #2 and both fans operated at high speed.   
      
   RW> TW> The PCM will also enable the cooling fans after the ignition is   
   RW> TW> turned off. When the engine coolant temperature exceeds 113øC (235øF)   
   RW> TW> and the ignition is turned off, the cooling fans will be enabled on   
   RW> TW> low speed for 150 seconds.   
      
   RW> TW> Cooling Fans   
   RW> TW> The cooling fans are controlled by the PCM based on the   
   RW> TW> following inputs:   
      
   RW> TW> The A/C system.   
   RW> TW> The Engine Coolant Temperature (ECT) sensor.   
   RW> TW> The Vehicle Speed Sensor (VSS).   
      
   RW> TW> Looks like SEPERATE Functions to me controled by a combination of   
   RW> TW> Sensors and Relays.   
   RW> TW> ---   
   RW> TW>  þ SLMR 2.1a þ Typo Tom strikes agaoin   
   RW> TW>  * Origin: Fidonet Since 1991 Join Us: www.DocsPlace.org (1:123/140)   
      
   RW>         R\%/itt   
      
      
   RW>--- GoldED+/W32 1.1.5-31012   
   RW> * Origin: Texas Lone-Star - Texan, American, USAian  (1:387/22)   
   ---   
    þ SLMR 2.1a þ Typo Tom Strkes Again   
    * Origin: Fidonet Since 1991 Join Us: www.DocsPlace.org (1:123/140)