Corvette C7 HVAC issues
Melting Slicks
Joined: Feb 2018
Posts: 2,157
Likes: 1,032
From: North Texas
Just a few ounces, over or under, really degrades AC performance. Thats why a good AC techs weight in the charge. ( its also faster ). Only way to get it on the money.
Long time ago, 60s 70's 80's AC systems had a TXV and some had a throttle valve and a receiver / dryer with a sight glass.
These valves kept the pressure across the evaporated coil at ~ 30 psi, as good as it gets. You could under or over charge the system and it still worked good. Just watch the sight glass when it ran clear, no bubbles, add a little more ( which was stored in the receiver ) and you were good to go. Easy, never cared about small leaks. R12 was less than $1 / can that was then 16 oz.
Them good old days are long gone.................
Long time ago, 60s 70's 80's AC systems had a TXV and some had a throttle valve and a receiver / dryer with a sight glass.
These valves kept the pressure across the evaporated coil at ~ 30 psi, as good as it gets. You could under or over charge the system and it still worked good. Just watch the sight glass when it ran clear, no bubbles, add a little more ( which was stored in the receiver ) and you were good to go. Easy, never cared about small leaks. R12 was less than $1 / can that was then 16 oz.
Them good old days are long gone.................
Thread Starter
Heel & Toe
Joined: May 2023
Posts: 20
Likes: 4
I actually took it to a shop few months ago because my AC compressor wasn’t turning on for some reason, I believed they hooked up the machine and tried to do all the servicing and everything while the compressor wasn’t on. So that maybe what happened.
i ended up finding out the fix i just took out the fuse waited couple min and put the fuse back in for the HVAC controls and the compressor turned back on but that was after they tried to service it with the compressor not turning on
Last edited by JDizzle; Jun 2, 2023 at 10:40 AM.
Safety Car
Joined: Dec 2012
Posts: 3,844
Likes: 1,857
From: St. Louis Metro East IL
Thanks for sharing all of this. I have learned that pressures in range don't tell the whole story.
Learn something new every day.
Let us know if correct charge solved the problem.
Ron
Learn something new every day.
Let us know if correct charge solved the problem.
Ron
Burning Brakes
Joined: Jan 2019
Posts: 954
Likes: 377
From: Louisiana
A simple hand on those lines works wonders for finding a freezing system. Guess I'm old school.
Burning Brakes
Joined: Jan 2019
Posts: 954
Likes: 377
From: Louisiana
Charge by weight. A frozen evaporator caused by an undercharged system will literally freeze solid and the system will stop operating until it thaws.
Melting Slicks
Joined: Feb 2018
Posts: 2,157
Likes: 1,032
From: North Texas
Home AC you charge by sub cool or super heat depending on what type of orifice your system has. ( fixed or TXV ).
Cars now days need to be charged by weight, much to hard to get the proper charge just using gauges. This is due to newer systems use so little refrigerant. Off a ounce or two is a very large percentage of the total charge and gauges won't tell you this.
Gauges on cars will only tell you if it is working.
Back in the 90's Ford's Aerostar had a terrible issue with insufficent cooling mainly due to air flow across the condenser. You could 'tweet' the charge + - an ounce or so and make a big difference. Charge was tweeked for either city or highway driving.
Cars now days need to be charged by weight, much to hard to get the proper charge just using gauges. This is due to newer systems use so little refrigerant. Off a ounce or two is a very large percentage of the total charge and gauges won't tell you this.
Gauges on cars will only tell you if it is working.
Back in the 90's Ford's Aerostar had a terrible issue with insufficent cooling mainly due to air flow across the condenser. You could 'tweet' the charge + - an ounce or so and make a big difference. Charge was tweeked for either city or highway driving.
Last edited by Tinkertech; Jun 5, 2023 at 08:40 AM.
Heel & Toe
Joined: Sep 2023
Posts: 19
Likes: 7
From: New Jersey (Ask me what exit :)
I'm wondering if the system described is operating as intended. When the cabin temp reaches the "set" temperature, The system slows the fan and kicks off the compressor. Very similar to the thermostat in your house. Just a thought...
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Heel & Toe
Joined: Oct 2013
Posts: 23
Likes: 0
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!