I was driving my 95 Lumina APV yesterday & had thought I had the check engine light problem solved with replacing the vacuum hose to the fuel pressure regulator. I pulled the ECM fuse put it back in drove her a good 20 miles at all speeds. Before it would come on with in 2-5min. of driving her.
So I turned the heater on & the fan kicked on (i have noticed this in past so not sure if this is normal) anyway as soon as I put the heater on the CEL went on & stayed on. I turned the heater off the fan kicked off but the CEL stayed on. There was no hesitation or anything running wise. I just don't understand why the fan would kick on when I turn the heater on & more so why the CEL came on then?.
As I said a good 20 miles at all diffrent speeds & no CEL until I put the heater on!.
Fan kicks on when I turn heater on. on 1995 Chevrolet Lumina APV