Ac and vent controls problem

[blackgn231]

When ,I but it onto the vent is stays on defrost mode and will go to vent sometimes not sure if this is a vacuum problem has anyone had this problem and fixed it?

 

[mikestertwo]

You probably have a leak at the vacuum control switch on your heater control head unit or the vacuum switch itself is bad.

 

[69RSCLONE]

most likely the vacuum switch. The center plastic clip breaks and causes a leak and defaults to defogger

Sent from my SM-G935V using Tapatalk

 

[Buckshot G/N]

BlackGN231 .did that info help any .I'm having a similar problem ,where yours blows out the defroster area,mind blows out the floor area. an if run the
car for maybe an hour or so the vacuum open an blows threw the vents.??

 

[Shawn N]

You have a dead actuator or the vacuum port has come loose from the actuator causing it to stay open.

 

[TurboTnZ06]

Could be simpler. If you remove the check valves in the engine bay (they break and need replacing over the years) you could have simply pressurized the lines that go under the passenger side firewall area under dash. There is a block there that run those vacuum lines to the HVAC controls. Mine did that. Easy fix, just plug them back in. Might be able to reach them through the glove box, not sure, it's been forever but thats the easiest problem to have. You do not want to be messing with the actual HVAC parts if you can help it.

 

[Buckshot G/N]

Thanks Guys for the info , now I have a starting point, plus I have all winter to tinker with until A/C Season. This might be a great project Thanksgiving
,after that meal I may need to do something. LOL !

 

[Shawn N]

The heater, vent, and defroster actuators are buried behind the dash in the radio area. A/c ones in the glove box area. You will have to pull out the dash to have free access to them. Just plug back up the hvac controls and you can switch the modes around to see which door is not working properly. If I remember correctly there is a pivot on the heater door that can also wear out. It would also be a good idea to label and bag fasteners to prevent loss and those where the hell does this fastener go moments.

 

[Buckshot G/N]

Just talked with and old school retired buick technician ,an he echo what you post.Thanks Shawn N !!

 

[TurboTnZ06]

Because we're boosted, I'd go digging for that simple manifold block thing under the pass glovebox, 100000000x easier to plug that back together if it came loose under boost, rather than screwing with taking the whole dash apart as the first choice of diagnosis.