AC air vent block issue!!!

[PlunkZ71]

Hey new here but was hoping someone could help.

I have a 2013 Z71 Tahoe with dual climate control.

Issue is with the AC. Everything works fine except when its been on for some time. When I drive down to Austin from Dallas with the AC on, AC blows through dash vents fine, but after its been on for awhile, I hear the air struggling to get through the dash vents. Mainly the 2 center vents. So no air comes through but I can tell its still cold, air still trying to blow hard and is loud. I usually have it on 72. The only way I can fix it is if I turn off the AC completely and wait a few minutes, then turn the AC back on and it blows again. Its a blend door or recirculation door blocking the vents, but for what reason? Its not diverting the air to the floor and doesnt feel like its blowing through the defrost vents either.

Is this normal? Like is it a sensor that activates the door once it reaches the programed interior temp? I have tried to turn down the temp all the way to see if this fixes it with no luck. I turn off recirculation, its not on auto. gets stuffy with no air coming out of the vents even though the air is on. I pulled the glove box and checked both actuators on the passenger side with my finger to see if they are working and they are.

Maybe a recalibration? Bad sensor? Any ideas?

 

[swathdiver]

Hey new here but was hoping someone could help.

I have a 2013 Z71 Tahoe with dual climate control.

Issue is with the AC. Everything works fine except when its been on for some time. When I drive down to Austin from Dallas with the AC on, AC blows through dash vents fine, but after its been on for awhile, I hear the air struggling to get through the dash vents. Mainly the 2 center vents. So no air comes through but I can tell its still cold, air still trying to blow hard and is loud. I usually have it on 72. The only way I can fix it is if I turn off the AC completely and wait a few minutes, then turn the AC back on and it blows again. Its a blend door or recirculation door blocking the vents, but for what reason? Its not diverting the air to the floor and doesnt feel like its blowing through the defrost vents either.

Is this normal? Like is it a sensor that activates the door once it reaches the programed interior temp? I have tried to turn down the temp all the way to see if this fixes it with no luck. I turn off recirculation, its not on auto. gets stuffy with no air coming out of the vents even though the air is on. I pulled the glove box and checked both actuators on the passenger side with my finger to see if they are working and they are.

Maybe a recalibration? Bad sensor? Any ideas?

Welcome to the forum Jeff. It sounds as if you have an actuator or two on the fritz. The best way to tell is to hook up a scan tool that can ride BCM codes. It can tell you which actuator has failed and why and also watch how the system performs in real-time. The likely offenders are the Mode Actuator and or the Air Inlet Valve Actuator (Recirc).

 

[PlunkZ71]

Welcome to the forum Jeff. It sounds as if you have an actuator or two on the fritz. The best way to tell is to hook up a scan tool that can ride BCM codes. It can tell you which actuator has failed and why and also watch how the system performs in real-time. The likely offenders are the Mode Actuator and or the Air Inlet Valve Actuator (Recirc).

Thanks for the quick reply and insight. Was hoping for an easier fix but let me see if I can get my hands on a scan tool that will read BCM codes. any insight on an affordable one?

 

[kbuskill]

It sounds to me like your evaporator is freezing up and not allowing air through. Turning it off for a few minutes allows the evaporator to thaw out/ defrost and then it works again... until it freezes up again.

I would start by checking your evaporator drain line and make sure its draining properly.

 

[PlunkZ71]

It sounds to me like your evaporator is freezing up and not allowing air through. Turning it off for a few minutes allows the evaporator to thaw out/ defrost and then it works again... until it freezes up again.

I would start by checking your evaporator drain line and make sure its draining properly.

Drain line should be fine as i always see drainage in the driveway. Its definitely an actuator door that is blocking the vents as i can sometimes hear the actuator when i turn off the ac. Thats how i know when to turn it back on. The loud sound i hear is the air forcefully blowing against it, blocking it from the dash vents. Ill take a look to be safe. Thanks

:EDIT: The more I think about it and research that possible problem the more I think you are right. Thanks for the insight!!

 

[swathdiver]

Thanks for the quick reply and insight. Was hoping for an easier fix but let me see if I can get my hands on a scan tool that will read BCM codes. any insight on an affordable one?

The Tech-2 was the tool these vehicles were designed to be worked on with; along with the shop manual. They can be had now for about $300-350 and quickly pay for themselves. With this tool, you can know which actuators failed and why and perform the calibration the proper way afterwards. This knowledge alone will pay for the machine in money not given to a shop. If the AC is low on refrigerant, it will tell you the pressure and you can look that up with the ambient temperature to see if it is low.

The shop manual can be purchased from vendors on ebay in download pdf form or disc and or you can get a subscription to it at AllDataDIY. The two go hand in hand when troubleshooting.

@gpracer1 Marc, What do you think? You've forgotten more about AC systems than I know.

 

[PlunkZ71]

So.... starting to think @kbuskill has the right idea. Thinking its the evaporator coil freezing up causing low velocity of air out of the vents after a couple of hours with the AC on. Hard to replicate since I don't drive very far ver often. So my options are to have the dealer do a BCM scan and pay $110 for the diagnosis, buy a scanner and do it myself or start by hooking it up to a manifold and check out the pressure. Any advice on the next step to take to fix the issue??

 

[08grey]

Did you change your climate controll lately? Mine would do this on long trips. I needed to have the controller flashed at the dealer.

Sent from my SM-G973U1 using Tapatalk

 

[PlunkZ71]

Did you change your climate controll lately? Mine would do this on long trips. I needed to have the controller flashed at the dealer.

Sent from my SM-G973U1 using Tapatalk

No, everything is stock. good to know though.

 

[08grey]

Mine was exaclty what you mentioned before evaporator would ice up and my passenger side floor would sound like a wind tunnel. It was because i changed my climate controll because my buttons were worn down and didnt have the new one programmed to the truck correctlt.

Sent from my SM-G973U1 using Tapatalk

 

[AzDiamondBlue]

The Tech-2 was the tool these vehicles were designed to be worked on with; along with the shop manual. They can be had now for about $300-350 and quickly pay for themselves. With this tool, you can know which actuators failed and why and perform the calibration the proper way afterwards. This knowledge alone will pay for the machine in money not given to a shop. If the AC is low on refrigerant, it will tell you the pressure and you can look that up with the ambient temperature to see if it is low.

The shop manual can be purchased from vendors on ebay in download pdf form or disc and or you can get a subscription to it at AllDataDIY. The two go hand in hand when troubleshooting.

@gpracer1 Marc, What do you think? You've forgotten more about AC systems than I know.

Hello. You seem to know bit about the Tech 2. Do you know off hand if it will go down to a 2004 Yukon, or is it just for newer ones? Thanks!

 

[AzDiamondBlue]

Hello. You seem to know bit about the Tech 2. Do you know off hand if it will go down to a 2004 Yukon, or is it just for newer ones? Thanks!

Found my answer! Thanks for the tip. Buying a Tech 2...might save me some headaches

 

[PlunkZ71]

Well... went on a 12 hour trip to Colorado from Texas. evacuated the system, new orifice tube under the hood, sucked it down and filled to spec. the trip there was fine but on the way back into the texas heat, the symptoms started towards the last leg of the drive. I pulled in the driveway and popped the hood and the accumulator/drier was frozen solid. Im sure the evaporator is freezing as well causing the air not to flow through the vents. So whats the next step to figuring this issue out? Refrigerant temp sensor? Low pressure switch?

View media item 27965

 

[kbuskill]

Well... went on a 12 hour trip to Colorado from Texas. evacuated the system, new orifice tube under the hood, sucked it down and filled to spec. the trip there was fine but on the way back into the texas heat, the symptoms started towards the last leg of the drive. I pulled in the driveway and popped the hood and the accumulator/drier was frozen solid. Im sure the evaporator is freezing as well causing the air not to flow through the vents. So whats the next step to figuring this issue out? Refrigerant temp sensor? Low pressure switch?

View media item 27965

Unfortunately GM cheaped out and didn't install a cabin air filter in the NNBS trucks.

I would start by buying the cabin air filter retrofit kit which comes with the door and filter and I would cut the "door" open and use a good foaming coil cleaner and clean your evaporator coils really well before installing the new filter and door.

Most of the time if an A/C is freezing up it is either a freon/pressure issue or a dirty evaporator coil not allowing enough air flow.

My 2 bits... YMMV

 

[PlunkZ71]

View media item 27965View media item 27965

Unfortunately GM cheaped out and didn't install a cabin air filter in the NNBS trucks.

I would start by buying the cabin air filter retrofit kit which comes with the door and filter and I would cut the "door" open and use a good foaming coil cleaner and clean your evaporator coils really well before installing the new filter and door.

Most of the time if an A/C is freezing up it is either a freon/pressure issue or a dirty evaporator coil not allowing enough air flow.

My 2 bits... YMMV

Thanks for the tip but I actually just retrofitted a cabin air filter right before I left and evacuated the system and charged to spec. Evap looks new when i took this pic through the hole i cut for the filter. I rinsed the condenser off as well. I have noticed that the compressor clutch never seems to disengage when the ac is on.

 

[kbuskill]

View media item 27965View media item 27965


Thanks for the tip but I actually just retrofitted a cabin air filter right before I left and evacuated the system and charged to spec. Evap looks new when i took this pic through the hole i cut for the filter. I rinsed the condenser off as well. I have noticed that the compressor clutch never seems to disengage when the ac is on.

View attachment 228989

Good to know that's not the issue... its possible that it could a pressure switch or temperature sensor...as mentioned before, a Tech2 would be very helpful in determining the culprit.

 

[PlunkZ71]

Good to know that's not the issue... its possible that it could a pressure switch or temperature sensor...as mentioned before, a Tech2 would be very helpful in determining the culprit.

Thanks again. As much as I hate stealerships, I think i'm going to bite the the bullet and get the dealer to do a diagnostic check for $110. At least then ill have a leg to stand on and I can plan my attack.

 

[kbuskill]

Thanks again. As much as I hate stealerships, I think i'm going to bite the the bullet and get the dealer to do a diagnostic check for $110. At least then ill have a leg to stand on and I can plan my attack.

I hear you... just FYI... 3 stealership diagnostic fees would pay for a Tech2 clone and you could use it as much as you want/need.

Just something to think about.

 

[PlunkZ71]

I hear you... just FYI... 3 stealership diagnostic fees would pay for a Tech2 clone and you could use it as much as you want/need.

Just something to think about.

Can you recommend one to get or link me to a known good one? Ive been debating getting one. Ive heard that there is a seperate sd card for GM trucks in order to read ones like the Tahoe. Also, im sure the learning curve will slow the process down.

 

[kbuskill]

Can you recommend one to get or link me to a known good one? Ive been debating getting one. Ive heard that there is a seperate sd card for GM trucks in order to read ones like the Tahoe. Also, im sure the learning curve will slow the process down.

@swathdiver
@iamdub
@Rocket Man
@Doubeleive

One of these guys can surely point you in the right direction for the Tech2.