Corvette C7 HVAC issues
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
Corvette C7 HVAC issues
Hi everyone first time posting here but need some assistance with my C7 HVAC system.
The issue I am having is that on my 2014 Z51 when the AC is on for a while like an hour. It feels like the vents are closing on it own because the air flow is not as strong. So I will turn it up to the highest setting you can hear the blower motor getting louder but the air from the vents is very weak like something blocking the airflow/vents closing . So I’m not sure why it’s doing that. I don’t change any setting it just does it on it own. The temp is on low and when I switch to different position like defroster or feet it moves but the air flow is still weak.
I am thinking it may be the AC control module? Or maybe the actuator that controls the vents?
Please help!
The issue I am having is that on my 2014 Z51 when the AC is on for a while like an hour. It feels like the vents are closing on it own because the air flow is not as strong. So I will turn it up to the highest setting you can hear the blower motor getting louder but the air from the vents is very weak like something blocking the airflow/vents closing . So I’m not sure why it’s doing that. I don’t change any setting it just does it on it own. The temp is on low and when I switch to different position like defroster or feet it moves but the air flow is still weak.
I am thinking it may be the AC control module? Or maybe the actuator that controls the vents?
Please help!
Safety Car
Joined: Dec 2012
Posts: 3,841
Likes: 1,856
From: St. Louis Metro East IL
You state that your problem is with air flow, not temperature. Start with the basics - have you changed the cabin air filter? A dirty filter will restrict air flow...
You state the mode changes and you can hear the different blower speeds so the electrical controls seem to be working. You may also want to remove the blower (only a few fasteners below the glove box) and clean the blower wheel or replace the blower motor and wheel.
GL
Ron
You state the mode changes and you can hear the different blower speeds so the electrical controls seem to be working. You may also want to remove the blower (only a few fasteners below the glove box) and clean the blower wheel or replace the blower motor and wheel.
GL
Ron
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
You state that your problem is with air flow, not temperature. Start with the basics - have you changed the cabin air filter? A dirty filter will restrict air flow...
You state the mode changes and you can hear the different blower speeds so the electrical controls seem to be working. You may also want to remove the blower (only a few fasteners below the glove box) and clean the blower wheel or replace the blower motor and wheel.
GL
Ron
You state the mode changes and you can hear the different blower speeds so the electrical controls seem to be working. You may also want to remove the blower (only a few fasteners below the glove box) and clean the blower wheel or replace the blower motor and wheel.
GL
Ron
is there like an internal vent that close and opens for the airflow? I can check?
I believe the blower motor would still be good since I can still hear it going and getting stronger the higher I put the fan speed. If I turn off my car for alittle and turn it back on the air flow is normal. Then after driving for a while the air flow will get weaker and weaker.
Le Mans Master
Joined: Aug 2015
Posts: 6,884
Likes: 2,884
From: Toronto
Is the air blowing harder out of different vents? Some have experienced issues with the blender door actuator. It can be recalibrated at the dealer which has worked for some. Others have had to replace it.
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
So when I drive after a while and the air flow is weak and I try to change the settings to different vents it will still stay weak. But when everything works and I change the settings to different vents the airflow is strong how it’s suppose to be. It’s only after a while of driving the air flow starts to gradually get weaker
Burning Brakes
Joined: Jan 2019
Posts: 954
Likes: 376
From: Louisiana
Check the lines under the hood when that behavior occurs, looking for them to be iced. Sounds like the evaporator is icing up, which can happen from low refrigerant which would occur from a leak.
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
I just got the AC system service by checking the level of refrigerant etc. They said everything was good and no leaks. I can check under the hood when it happens again.
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Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
I thought about that, but since it’s on low wouldn’t it still keep blowing at a constant speed? I mean you can def tell when the air flow is weak it starts to get hot inside the cabin, also barely any air is coming out even if you have it in full blast. It feels like an internal vent from the blower is closing on its own.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,561
Likes: 4,031
From: Cape Coral, Florida
Hi everyone first time posting here but need some assistance with my C7 HVAC system.
The issue I am having is that on my 2014 Z51 when the AC is on for a while like an hour. It feels like the vents are closing on it own because the air flow is not as strong. So I will turn it up to the highest setting you can hear the blower motor getting louder but the air from the vents is very weak like something blocking the airflow/vents closing . So I’m not sure why it’s doing that. I don’t change any setting it just does it on it own. The temp is on low and when I switch to different position like defroster or feet it moves but the air flow is still weak.
I am thinking it may be the AC control module? Or maybe the actuator that controls the vents?
Please help!
The issue I am having is that on my 2014 Z51 when the AC is on for a while like an hour. It feels like the vents are closing on it own because the air flow is not as strong. So I will turn it up to the highest setting you can hear the blower motor getting louder but the air from the vents is very weak like something blocking the airflow/vents closing . So I’m not sure why it’s doing that. I don’t change any setting it just does it on it own. The temp is on low and when I switch to different position like defroster or feet it moves but the air flow is still weak.
I am thinking it may be the AC control module? Or maybe the actuator that controls the vents?
Please help!
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
I will try that right now. Only way to see if it works if I drive for more than an hour straight 😢 to see if it stays constant
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,561
Likes: 4,031
From: Cape Coral, Florida
Hopefully it works and if not on your drive I’d swing by your friendly parts store and maybe they can scan it…I don’t know what kind they use but hopefully it can scan for HVAC DTC’s.
Pro
Joined: May 2022
Posts: 566
Likes: 242
From: Peoria, Arizona
This may sound insignificant, but you said that you have the temp on Low. That means you are only recirculating inside air. AC systems need to have outside air over the coils after a while so they remain efficient. They get too cold otherwise, which results in less cooling, go figure. It's all about efficiency. Anyway, try cooling your car like you normally do but after a while push the button to recirc outside air. In order to protect the system, I wouldn't be surprised if the computer restricts air flow over the coils in an attempt to regain efficiency.
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
ok so I did it let’s see if it work. I also tried plugging in my scanner it didn’t see the HVAC module it seen transmission, airbags, etc.
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
This may sound insignificant, but you said that you have the temp on Low. That means you are only recirculating inside air. AC systems need to have outside air over the coils after a while so they remain efficient. They get too cold otherwise, which results in less cooling, go figure. It's all about efficiency. Anyway, try cooling your car like you normally do but after a while push the button to recirc outside air. In order to protect the system, I wouldn't be surprised if the computer restricts air flow over the coils in an attempt to regain efficiency.
so I went to check my car and the setting are usually set to not recirculating air. Looks like it’s always been on getting the outside air. I will def try tho recirculating and using the outside air
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Good luck figuring out why your HVAC is working like that. Hopefully it will turn out to just be a simple fix.
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
One detail I didn’t mention is that. When the airflow is really weak when the AC is on. I turn the temp on to Hi and then the airflow goes back to normal, but when I put it on low it doesn’t go back cold? It’s really weird. I would have to turn the car off for alittle then turn it back to have the cold air come back? Any one experience this?
Pro
Joined: May 2022
Posts: 566
Likes: 242
From: Peoria, Arizona
usually when you put your car on LOW temp, it automatically shuts off outside air and stays that way until you adjust the thermostat to a higher temp. So, yeah, I would pay attention to the recirc to eliminate this as an issue
Safety Car
Joined: Dec 2012
Posts: 3,841
Likes: 1,856
From: St. Louis Metro East IL
When you go to heat and the airflow increases - how long does the car need to be off before AC airflow is normal on restart? If several minutes this seems like the evaporator coil is freezing up and blocking air flow - again indicating low coolant pressure.
How consistent is the condensate drain flow? Hard to tell since it drips on the exhaust pipe, but a frozen coil would not drip as much... Do you hear condensate sizzle or see water under the passenger side of the car? Damp carpet on passenger side? Just wondering what problems a plugged condensate drain might cause beside wet carpet.
Ron
How consistent is the condensate drain flow? Hard to tell since it drips on the exhaust pipe, but a frozen coil would not drip as much... Do you hear condensate sizzle or see water under the passenger side of the car? Damp carpet on passenger side? Just wondering what problems a plugged condensate drain might cause beside wet carpet.
Ron
Burning Brakes
Joined: Jan 2019
Posts: 954
Likes: 376
From: Louisiana
One detail I didn’t mention is that. When the airflow is really weak when the AC is on. I turn the temp on to Hi and then the airflow goes back to normal, but when I put it on low it doesn’t go back cold? It’s really weird. I would have to turn the car off for alittle then turn it back to have the cold air come back? Any one experience this?
It sounds like your evaporator is freezing up.