Originally Posted by rich4159 (Post 597866)

if after you figure out which blend door actuator you need to replace manual or auto, you may end up with a very common problem were the blend door is cycling and unable to find it's limits. This problem has driven me crazy for six months since i changed the battery out. All the threads here and on most other sites give the basic calibration procedure. this says to remove the dro bat fuse for 20 seconds, with the power off, then put it back and turn the key to the on position for 40 secs. all good except it is missing a very key step.

I have finnally nailed the problem down thru an honest Chevy mechanic. "this is a known problem throughout many of the chevy product lines. in order to fix it the five volt signal needs to be jumped to one of the pins on the connector to the unit can first find it center positon. The aforementioned cal procedure can only find the limits but without the center position being first calibrated the DRO bat fuse removal procedure cannot work". This is exactly what i see happening. Chevy does have procedure for calibrating the unit about $100.00. but not to fret. there is a tsb 150-9645 that explains which pins to jump. I will post it as soon as i can. i did the procedure last night and it work!

Of course this is a real design issue that chevy will not take responsibility for and therefore they expect the owner to pay a 100.00 fee. Change a battery and then pay $100.00 to have heat and air conditioning again.

go figure.

Originally Posted by cudaguy71 (Post 680196)

Did you ever post the tsb 150-9645? Thank you...

Originally Posted by LannyL81 (Post 681358)

cudaguy71 and christine_208: since this thread is about three years old, doubt that the TSB was ever posted here, might try doing a Google search for it.

Are you both having hot air out the vents with AC on? Assuming the AC system is functional, easy thing to do is to watch the blend door actuator movement with the temp setting at full hot, then full cold...or the other way....just to see if it is moving then we can go from there.