Auto a/c issues

[Mdmax]

Hey all, I know these systems are complicated, just looking to get pointed in the right direction.  My 2005 sierras has the auto ac and seems to have a mind if it’s own.  With ac on (has to be set really low)it will blow cold but weak but it will ramp up got a little or blow warm for a little.  It won’t blow warm air until temp set into upper 80’s but it will blow warm then cool then warm .  Seems like the control panel maybe but I know there are a few sensors as well.  Maybe blend door issue? Thanks

[Super 8]

Will be a sensor with a tiny fan in it above your head that senses the cabin air temp. Replace this first and see if it helps.

[Mdmax]

So I did the actuator recalibration and seems to have helped the pass and drivers vents synchronize.So I think my thermostats are bad so I’m gonna swap those out.  Truck takes forever to warm up.   So upon further examination here are the issues.

1. Ac doesn’t get cold, heat doesn’t get hot

2. Pass and driver defrost vents blow different temps

3. Driver vent and defrost never blow hard, floor does

4.  With heat on auto setting will only blow from floor vents(maybe normal?)

5. Temps change from warm to cool and vice versa while driving

6. Also the manual says under 40* the compressor won’t run and the snowflake symbol will disappear.  This morning at 34* the symbol was on but compressor did not run.  Not sure if this is significant.  

Thanks

[Mdmax]

On 11/20/2017 at 11:03 AM, Super 8 said:

Will be a sensor with a tiny fan in it above your head that senses the cabin air temp. Replace this first and see if it helps.

This is on my list of parts to order, also gonna replace control panel for the hell of it.  Just need to figure out if I need mode actuator or blend or none.