96 chevy suburban when turned off a fan will kick on and off there has been a few times it killed my battery by doing this I know that chevy did this to get moisture out of the evap or something like that but I don't know why it would go until my battery dies any one with any suggestions

 

sounds like a bad sensor !

 

What sensor or sensors do i start checking

 

what fan is turning on?

 

I don't remember I just remember that a fan is suppose to kick on to remove moisture in the evap canister I do believe is what I found out when I looked up why a fan turns on for a few seconds then turns off when the suburbans ignition is off

 

So it's the fan under the dash I just heard it turn on for a second then off

 

there was an afterblow function that turns the blower motor fan on to remove moisture from the evaporator. the purpose is to stop bacterial/mold growth on the evaporator fins in hot climates. I thought it was only for model years in the 2000 or newer, never seen it in a 96. You can check with a scan tool. Go into the hvac or bcm modules with a full function scan tool and see if you can find "afterblow".

 

there should be a relay of some sort that turns the fan on and off and it could be sticking ! look by the fan and there should be a sensor there !