Heat comes and goes inside cab 2005 sierra

[kenman1717]

Truck is a 2005 sierra 2500 with a 6.6 duramax. It has the Auto HVAC controls. Sometimes everything works fine, great heat, then all of a sudden it goes away, doesn't really matter what position the blend doors are in, same type of thing happened with the a/c, kind of stopped and warm air started. It has a recurring code of B0229 Recirculation position feedback circuit range/performance with history codes of B0263 Airflow control 6 circuit and B3770 Airflow control 6 feedback circuit. I found a GM bulletin 04-01-38-008 A/C - Defaults To Defrost Mode/Poor Control, which actually outlines similar to what's going on, it said to check the wire harness behind the instrument panel cover, the picture which is not labeled looks like behind the glove box, and when I pulled it, looks very similar. Harness goes from left side temp actuator at bottom to the recirculation actuator at the top.
Bulletin outlines the wires chaffing, couldn't find any evidence of this. In the Bulletin it says the codes that may have set are B0229 as well as B3770, with others. But it says B3770 'Mode Actuator Cause' in the bulletin, but my Snap On scanner calls it something else. When I look up B0229 itself it just says to test the actuator, but its on top of the heater box under the dash, I can see it, but am unable to access the wires or the screws. Of all the reading I have done about this actuator, half say to pull the dash others say it can be done without. Everything is working all the modes and temps as well as recirculation, this is intermittent, but is becoming more noticeable as time goes on. And of all the reading I have done, only a few had this exact issue and It was fixed by the bulletin or and actuator. Called GM to see if they had any programming updates, but they said they couldn't tell just from the vin, had to be hooked up to tell. As far I know this truck hasn't had any major repairs at a dealer that would require programming. Was owned by an older couple, very low mileage for the year only 157 000kms, truck is in great shape. It has sat a lot, up till now just really minor stuff has needed to be fixed. Its an Alberta truck, but it has very little rust underneath, not on the body.
Anybody experience and thing like this before?

[kenman1717]

I took the truck in so they could check for updates. There was actually some for the HVAC controls surprisingly. They didn't update anything else, I figured there would be more, but anyway. I guess they ran the truck up to temp, after they scanned it and found the B0229 code. They told me it needed thermostats because the heat quality wasn't good. They wanted a stupid amount of money to do them, I'm a licensed mechanic so I wasn't going to let them do it, I just wanted programming updates. I did change the thermostats, after I talked to the couple that used to own the truck, they said they had never been done. We'll see how this works out, I still leaning toward an electrical/actuator issue.