Air Conditioning problem
Thread Starter
Melting Slicks
Joined: Feb 2005
Posts: 3,466
Likes: 41
From: Auburn MA
Air Conditioning problem
I went to go use my AC on my 94 Vette and it wouldn't blow cold air.... what is the easiest way to diagnose this issue. Where is the fuse and relay so i can rule out the easiest and how do i know of it is low on refrigerant. The car is equipped with the climate control system
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
I went to go use my AC on my 94 Vette and it wouldn't blow cold air.... what is the easiest way to diagnose this issue. Where is the fuse and relay so i can rule out the easiest and how do i know of it is low on refrigerant. The car is equipped with the climate control system
C4 Corvette Climate Control Codes - YouTubeVideo for youtube corvette climate control▶ 4:46
www.youtube.com/watch?v=lWIrT8tN-a8
Nov 27, 2013 - Uploaded by ChrisFix
C4 Corvette check engine light, or in this case check air conditioning system light can be used ...
Last edited by antfarmer2; Apr 23, 2015 at 01:14 PM.
Thread Starter
Melting Slicks
Joined: Feb 2005
Posts: 3,466
Likes: 41
From: Auburn MA
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
If low on Freon the compressor clutch will be continuously cycling on and off. Do NOT randomly just add Freon, an overcharge can damage the system. You need gauges to determine the Freon level.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Step #1 hook up a gauge set and check system Static, and Dynamic pressure if possible. Trouble shoot from there..
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Burning Brakes
Joined: May 2006
Posts: 1,208
Likes: 1
From: Elgin IL
If the system has no freon in it the compressor clutch will not engage. If the system is low on freon the clutch will cycle on and off.
If the system is very low on freon that the compressor will not engage you could see pressure on the system but probally will not.
If they system worked last season with out an issue and now it does not then you probally have a leak.
If the system is very low on freon that the compressor will not engage you could see pressure on the system but probally will not.
If they system worked last season with out an issue and now it does not then you probally have a leak.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
If the system has no freon in it the compressor clutch will not engage. If the system is low on freon the clutch will cycle on and off.
If the system is very low on freon that the compressor will not engage you could see pressure on the system but probally will not.
If they system worked last season with out an issue and now it does not then you probally have a leak.
If the system is very low on freon that the compressor will not engage you could see pressure on the system but probally will not.
If they system worked last season with out an issue and now it does not then you probally have a leak.
that's what mine did fixed the valve and added freon worked great but how do you use the gauges with low freon and compressor not kicking on? 
and if you can how much pressure will there be?
Last edited by antfarmer2; Apr 23, 2015 at 04:18 PM.
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
Key word is "low". Other than a major leak, which will leave an oily residue, expect the system to have a small leak with Freon still in the system. Just not enough Freon to keep the binary/trinary switch from disabling the compressor's clutch. You can bypass this switch with a paperclip as a test, but may damage the compressor if you by-pass it longer than a very short test.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Key word is "low". Other than a major leak, which will leave an oily residue, expect the system to have a small leak with Freon still in the system. Just not enough Freon to keep the binary/trinary switch from disabling the compressor's clutch. You can bypass this switch with a paperclip as a test, but may damage the compressor if you by-pass it longer than a very short test.
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
So damage can be done and can't use the gauges with out the compressor running still learning here Every one I have had troulble with was just low from a leaky shrader valve and once I started putting freon in the compressor started kicking on kept putting freon in till line was beer can cold then spit in the valves found air bubbles then changed out the shrader valve
Race Director
Joined: Feb 2002
Posts: 11,599
Likes: 1,053
From: Compound in the Grove, Ga.
2026 Corvette of the Year Finalist - Unmodified
2025 C4 of the Year Winner - Unmodified
2024 C4 of the Year Finalist - Unmodified
2020 C3 of the Year Finalist - Unmodified
2019 C4 of Year Finalist (performance mods)
2018 C4 of Year Finalist
2015 C4 of the Year Finalist
St. Jude Donor '16
My 95 LT1 car sat for a few years, No AC compressor would not cycle on. I hooked up my gauges added the first can compressor than came on and I finished refilling system to the correct pressures per the recommended chart in the FSM based on the outside temp. You can also jump one of the pressure switches to turn on the compressor I think its the low presser switch. Please check your FSM on refilling the system before you attempt doing anything...
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Oh but it can Come on.. the gauges will tell you (without guessing) whether or not the Pump Should, or should not engage, based on what gas there is "Currently" in the air-conditioning system. This will mitigate the possibility of you from Overcharging, and or running the pump while low on gas..
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Oh but it can Come on.. the gauges will tell you (without guessing) whether or not the Pump Should, or should not engage, based on what gas there is "Currently" in the air-conditioning system. This will mitigate the possibility of you from Overcharging, and or running the pump while low on gas..
what will it show and what to look for?
Last edited by antfarmer2; Apr 23, 2015 at 05:50 PM.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Lets say that there is enough (Freon) pressure in the system in order to close the low pressure switch, The Compressor should engage, if the system is low on (Freon) the low side pressure will quickly drop, and the Low side pressure switch will open, thus shutting down the Compressor.
On the other hand this may inform you that there is a faulty High/Low pressure switch..
The FSM gives the exact pressure/performance settings.
Anyhow here is a decent Link with a detailed explanation:
http://aircondition.com/tech/questio...ith-Gauges-FAQ
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Good Question!
Lets say that there is enough (Freon) pressure in the system in order to close the low pressure switch, The Compressor should engage, if the system is low on (Freon) the low side pressure will quickly drop, and the Low side pressure switch will open, thus shutting down the Compressor.
On the other hand this may inform you that there is a faulty High/Low pressure switch..
The FSM gives the exact pressure/performance settings.
Anyhow here is a decent Link with a detailed explanation:
http://aircondition.com/tech/questio...ith-Gauges-FAQ
Lets say that there is enough (Freon) pressure in the system in order to close the low pressure switch, The Compressor should engage, if the system is low on (Freon) the low side pressure will quickly drop, and the Low side pressure switch will open, thus shutting down the Compressor.
On the other hand this may inform you that there is a faulty High/Low pressure switch..
The FSM gives the exact pressure/performance settings.
Anyhow here is a decent Link with a detailed explanation:
http://aircondition.com/tech/questio...ith-Gauges-FAQ
Thread Starter
Melting Slicks
Joined: Feb 2005
Posts: 3,466
Likes: 41
From: Auburn MA
Where do I get one of these gauges and where do I put it. My car has two valves one on the fatter hose closer to the heater box and one on a skinnier hose. Is it OK to just use the gauge that comes with the cans of R34
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579