This has been going on for a while but seems to have gotten more intense. At least my wife has gotten more intense for me to make it stop. Blazer runs great but the problem is that it's idle will be either 600-700 rpms or double that at 1100 or so. When it is in the lower more normal range it will stay constant when AC compressor goes on and off. When it is in the fast range the AC compressor going on and off will make it range all the way up to 2000. I believe that the higher rpm is when the compressor is off. After a few days of paying extra attention to this happening it seems like when the engine is started it will be one way or the other but It doesn't seem to go back and forth after it is running. I cleaned the throttle linkage and the butterfly and tested the Throttle position sensor which tested perfect with no intermittants. I verified that it is not just when the AC is switched on, with it off the faster rpm just stays at that 1100 mark. I checked for loose connections at sensors but could not affect it. I feel like it must be a simple problem but where to look I would appreciate anyones directions.

 

How many counts for the IAC is the VCM commanding when the problem happens? Compare this to counts when the problem is not there and report please.


I know you're not getting a SES light, but please read this


https://blazerforum.com/forum/diagno...plained-35140/

 

I will be working to get this information! Thanks for giving me a direction.