Which AC port is this?
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
Thanks!
AC is blowing HOT.
What do y’all recommend usually? trial a can of 134a, or just bite the bullet and go to a shop?
i’ve had the car about 6 weeks and it’s never blown cold, so my inclination is to have the shop at least evacuate the system and refill so i have a good baseline
AC is blowing HOT.
What do y’all recommend usually? trial a can of 134a, or just bite the bullet and go to a shop?
i’ve had the car about 6 weeks and it’s never blown cold, so my inclination is to have the shop at least evacuate the system and refill so i have a good baseline
Last edited by fastbanana; May 23, 2023 at 05:11 PM.
Melting Slicks
Joined: May 2014
Posts: 2,895
Likes: 592
From: New Port Richey FL
Before you just throw a can at it take a look around the Whole a/c system look at all the pipes joints and connections, look for wet super Oily spots. If really wet its going to seals. If whined up opening the system to seal something it will need to be Evacuated and drawn down. So Minor leak a Can or two.
If your unsure of your Abilities see a shop
If your unsure of your Abilities see a shop
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
Before you just throw a can at it take a look around the Whole a/c system look at all the pipes joints and connections, look for wet super Oily spots. If really wet its going to seals. If whined up opening the system to seal something it will need to be Evacuated and drawn down. So Minor leak a Can or two.
If your unsure of your Abilities see a shop
If your unsure of your Abilities see a shop
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
IMHO - there is a fair amount you can do before there is a need to see a shop.
Step 1 - does the compressor engage when A/C is called for.
If not - it could be due to low system pressure, or it could be due to a bad compressor clutch or it could be electrical wiring related.
If the Compressor does not engage - I would start by checking the system pressure. You can do this with a manifold gauge set (available at Harbor Freight for less than $60 - sometimes around $45 on sale), or with one of the cheap refrigerant add kits you can buy at Wal Mart - that HAS a pressure gauge built in. This cheaper version will only measure low side pressure- but that's WAY better than nothing. You should have at least 30 psi in the system before the A/C compressor engages.
If the Compressor Does engage - let it run for a half minute or so - and then feel the temp of the low side and high side lines (the two lines that attach to the compressor). One should be cool, and one should be hot. If that's the case - it sounds like the A/C is sorta running OK - and the problem is likely in the interior air control system.
Let us know what you find...
Step 1 - does the compressor engage when A/C is called for.
If not - it could be due to low system pressure, or it could be due to a bad compressor clutch or it could be electrical wiring related.
If the Compressor does not engage - I would start by checking the system pressure. You can do this with a manifold gauge set (available at Harbor Freight for less than $60 - sometimes around $45 on sale), or with one of the cheap refrigerant add kits you can buy at Wal Mart - that HAS a pressure gauge built in. This cheaper version will only measure low side pressure- but that's WAY better than nothing. You should have at least 30 psi in the system before the A/C compressor engages.
If the Compressor Does engage - let it run for a half minute or so - and then feel the temp of the low side and high side lines (the two lines that attach to the compressor). One should be cool, and one should be hot. If that's the case - it sounds like the A/C is sorta running OK - and the problem is likely in the interior air control system.
Let us know what you find...
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
IMHO - there is a fair amount you can do before there is a need to see a shop.
Step 1 - does the compressor engage when A/C is called for.
If not - it could be due to low system pressure, or it could be due to a bad compressor clutch or it could be electrical wiring related.
If the Compressor does not engage - I would start by checking the system pressure. You can do this with a manifold gauge set (available at Harbor Freight for less than $60 - sometimes around $45 on sale), or with one of the cheap refrigerant add kits you can buy at Wal Mart - that HAS a pressure gauge built in. This cheaper version will only measure low side pressure- but that's WAY better than nothing. You should have at least 30 psi in the system before the A/C compressor engages.
If the Compressor Does engage - let it run for a half minute or so - and then feel the temp of the low side and high side lines (the two lines that attach to the compressor). One should be cool, and one should be hot. If that's the case - it sounds like the A/C is sorta running OK - and the problem is likely in the interior air control system.
Let us know what you find...
Step 1 - does the compressor engage when A/C is called for.
If not - it could be due to low system pressure, or it could be due to a bad compressor clutch or it could be electrical wiring related.
If the Compressor does not engage - I would start by checking the system pressure. You can do this with a manifold gauge set (available at Harbor Freight for less than $60 - sometimes around $45 on sale), or with one of the cheap refrigerant add kits you can buy at Wal Mart - that HAS a pressure gauge built in. This cheaper version will only measure low side pressure- but that's WAY better than nothing. You should have at least 30 psi in the system before the A/C compressor engages.
If the Compressor Does engage - let it run for a half minute or so - and then feel the temp of the low side and high side lines (the two lines that attach to the compressor). One should be cool, and one should be hot. If that's the case - it sounds like the A/C is sorta running OK - and the problem is likely in the interior air control system.
Let us know what you find...
thank you!
if there is no system pressure, would i just add my own refrigerant? trying to figure out where I hit the cost of a shop vs the cost of trying to diagnosis this on my own.
I think most of the 50$ bottles of refrigerant have the pressure gauge
Pro
Joined: Mar 2007
Posts: 596
Likes: 355
From: Mt Prospect IL
2025 C4 of the Year Finalist - Unmodified
No one seems to have answered your original question. The car was R12 when manufactured and someone converted it to R134. As others have said, put a can in and we if the clutch engages. Watch for leaks, if no leaks, continue to charge till system operating normally.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
I sort of figured it was r134 after comparing stocks parts to mine. I also got the feeling i was overthinking the whole process and maybe need to just throw a can in there.
Race Director
Joined: Jun 2020
Posts: 10,687
Likes: 2,251
From: north of Chicago
2025 C2 of the Year ('64-'66) Finalist - Unmodified
2025 C3 of the Year Finalist - Modified
2025 C4 of the Year Finalist - Modified
2024 C4 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
2023 C4 of the Year Finalist- Modified
2022 C4 of the Year Finalist - Modified
2022 C3 of the Year Finalist - Modified
2021 C7 of the Year Winner -- Modified
2020 C4 of the Year Finalist - Modified
You did not specify the year of your car, so here is one of my tests
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the fender well on one of the steel lines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short blasts for comprssor system to react to new pressures
Hope this helps
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the fender well on one of the steel lines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short blasts for comprssor system to react to new pressures
Hope this helps
Last edited by walleyfisher; May 24, 2023 at 01:34 PM.
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
You did not specify the year of your car, so here is one of my tests
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the frnder well on one of the steel ines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short plasts for comprssor system to react to new pressures
Hope this helps
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the frnder well on one of the steel ines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short plasts for comprssor system to react to new pressures
Hope this helps
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
IMHO - there is a fair amount you can do before there is a need to see a shop.
Step 1 - does the compressor engage when A/C is called for.
If not - it could be due to low system pressure, or it could be due to a bad compressor clutch or it could be electrical wiring related.
If the Compressor does not engage - I would start by checking the system pressure. You can do this with a manifold gauge set (available at Harbor Freight for less than $60 - sometimes around $45 on sale), or with one of the cheap refrigerant add kits you can buy at Wal Mart - that HAS a pressure gauge built in. This cheaper version will only measure low side pressure- but that's WAY better than nothing. You should have at least 30 psi in the system before the A/C compressor engages.
If the Compressor Does engage - let it run for a half minute or so - and then feel the temp of the low side and high side lines (the two lines that attach to the compressor). One should be cool, and one should be hot. If that's the case - it sounds like the A/C is sorta running OK - and the problem is likely in the interior air control system.
Let us know what you find...
Step 1 - does the compressor engage when A/C is called for.
If not - it could be due to low system pressure, or it could be due to a bad compressor clutch or it could be electrical wiring related.
If the Compressor does not engage - I would start by checking the system pressure. You can do this with a manifold gauge set (available at Harbor Freight for less than $60 - sometimes around $45 on sale), or with one of the cheap refrigerant add kits you can buy at Wal Mart - that HAS a pressure gauge built in. This cheaper version will only measure low side pressure- but that's WAY better than nothing. You should have at least 30 psi in the system before the A/C compressor engages.
If the Compressor Does engage - let it run for a half minute or so - and then feel the temp of the low side and high side lines (the two lines that attach to the compressor). One should be cool, and one should be hot. If that's the case - it sounds like the A/C is sorta running OK - and the problem is likely in the interior air control system.
Let us know what you find...
well, the system has plenty of pressure, at least 40psi on this bottle of freon i just bought. The clutch is not engaging however on the compressor. Any thoughts on how to proceed? i’m not sure which switch to jump to get it going
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
ok so here’s where i currently am with the AC system.
1: low pressure system is fully charged between 40-50 psi
2: high pressure cut off switch has zero ohms/ is closed
3: pressure cycling switch is OPEN with no power, and when i jump this switch the compressor runs!
4. I disconnected the battery and let the car sit for 10 minutes: no change
will get a new switch and report back
1: low pressure system is fully charged between 40-50 psi
2: high pressure cut off switch has zero ohms/ is closed
3: pressure cycling switch is OPEN with no power, and when i jump this switch the compressor runs!
4. I disconnected the battery and let the car sit for 10 minutes: no change
will get a new switch and report back
Last edited by fastbanana; May 24, 2023 at 02:51 PM.
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
IVE GOT SOME COLD AIR BABY.
I jumped the PCV which got the compressor going and allowed me to fill with freon. Currently at 35psi @ 75 ambient and blowing 60 at idle. I replaced the PCV for good measure but i think that was overkill. Thanks for the help
I jumped the PCV which got the compressor going and allowed me to fill with freon. Currently at 35psi @ 75 ambient and blowing 60 at idle. I replaced the PCV for good measure but i think that was overkill. Thanks for the help
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
You did not specify the year of your car, so here is one of my tests
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the fender well on one of the steel lines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short blasts for comprssor system to react to new pressures
Hope this helps
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the fender well on one of the steel lines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short blasts for comprssor system to react to new pressures
Hope this helps
Thread Starter
Instructor
Joined: Apr 2023
Posts: 103
Likes: 7
You did not specify the year of your car, so here is one of my tests
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the fender well on one of the steel lines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short blasts for comprssor system to react to new pressures
Hope this helps
Look for the AC pressure sensor/ switch (on mine ('74)) its located on the fender well on one of the steel lines near the compressor and has (2) wires connected to it.
Newer ones some have them on the back of the compressor or on the accumilator. This sensor has to be closed for the compressor to operate so if the pressure is low the switch is open
What I would do first is find yourself a jumper wire, unplug the AC pressure / switch plug, start the car up (with AC on max) and jumper the two connections on the plug and see if the compressor fires up, if it does it most likely needs more freon. If it does, it usually doesn't need much and too much pressure is bad too. So if you need to add, re plug the sensor /switch connection and while the car is running add freon until the clutch just starts to engage (give it short blasts for comprssor system to react to new pressures
Hope this helps
