[C2] A/C issues
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
A/C issues
Yesterday we had a relatively hot day over here and I took the '64 down-town looking forward to the benefits of my recently charged a/c. Although as some of you might have read it's not working as well as it should.
While driving there was a strange noise somewhere on the passenger side. Sort of hissing, sucking. Not constant. On for a while, then off again and returning. And so on. Is that normal for the a/c system?
Unfortunately after a while a much worse, loud screeching noise occured. Sounded like a belt. Would dissapear depending on the RPMs. The belt looks rather new. Has it to do with the tension of the belt? When I turn of the a/c it stops.
While driving there was a strange noise somewhere on the passenger side. Sort of hissing, sucking. Not constant. On for a while, then off again and returning. And so on. Is that normal for the a/c system?
Unfortunately after a while a much worse, loud screeching noise occured. Sounded like a belt. Would dissapear depending on the RPMs. The belt looks rather new. Has it to do with the tension of the belt? When I turn of the a/c it stops.
Le Mans Master
Joined: Feb 2012
Posts: 5,361
Likes: 2,872
From: Western Massachusetts
2024 C2 of the Year Finalist - Unmodified
2023 C2 of the Year Finalist - Unmodified
2019 C2 of Year Finalist (stock)
2015 C2 of the Year Finalist
Yesterday we had a relatively hot day over here and I took the '64 down-town looking forward to the benefits of my recently charged a/c. Although as some of you might have read it's not working as well as it should.
While driving there was a strange noise somewhere on the passenger side. Sort of hissing, sucking. Not constant. On for a while, then off again and returning. And so on. Is that normal for the a/c system?
Unfortunately after a while a much worse, loud screeching noise occured. Sounded like a belt. Would dissapear depending on the RPMs. The belt looks rather new. Has it to do with the tension of the belt? When I turn of the a/c it stops.
While driving there was a strange noise somewhere on the passenger side. Sort of hissing, sucking. Not constant. On for a while, then off again and returning. And so on. Is that normal for the a/c system?
Unfortunately after a while a much worse, loud screeching noise occured. Sounded like a belt. Would dissapear depending on the RPMs. The belt looks rather new. Has it to do with the tension of the belt? When I turn of the a/c it stops.
The high side pressure should be roughly 2.5 X ambient temperature in front of the condenser, the low side between 25 and 35. Swirling noises can sometimes be heard in an evaporator as the TX valve meters refrigerant, but I wouldn't go by noises, go by pressure readings.
Dan
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
Pulling as hard as I can by hand doesn't move the belt at all. So to me it seems to be tight. It's the original system.
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
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
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
It's R437a. Which is supposed to be a direct replacement for R12, I.e. the system gets charged with the same weight of refigerant.
Race Director
Joined: Mar 2002
Posts: 13,633
Likes: 3,580
From: NorCal
Yesterday we had a relatively hot day over here and I took the '64 down-town looking forward to the benefits of my recently charged a/c. Although as some of you might have read it's not working as well as it should.
While driving there was a strange noise somewhere on the passenger side. Sort of hissing, sucking. Not constant. On for a while, then off again and returning. And so on. Is that normal for the a/c system?
Unfortunately after a while a much worse, loud screeching noise occured. Sounded like a belt. Would dissapear depending on the RPMs. The belt looks rather new. Has it to do with the tension of the belt? When I turn of the a/c it stops.
While driving there was a strange noise somewhere on the passenger side. Sort of hissing, sucking. Not constant. On for a while, then off again and returning. And so on. Is that normal for the a/c system?
Unfortunately after a while a much worse, loud screeching noise occured. Sounded like a belt. Would dissapear depending on the RPMs. The belt looks rather new. Has it to do with the tension of the belt? When I turn of the a/c it stops.
Burning Brakes
Joined: Jan 2002
Posts: 1,173
Likes: 458
From: Ct
2026 Corvette of the Year Finalist - Unmodified
2025 C3 ('68-'73) of the Year Winner - Unmodified
2024 Corvette of the Year Finalist - Modified
2023 C1 of the Year Winner - Modified
2022 Corvette of the Year Finalist -- Unmodified
2021 C2 of the Year Winner - Unmodified
Factory AC Belt Screech
First - I don't claim to be a resident expert on factory AC - there are many others that have that title ... that said I do have a factory Corvette AC car and am always learning. What I understand is:
Belt screeching may be an indication of a bigger problem .. possible over oil or over gas. On a factory A6 The belt should have 3/4" up and 3/4 " down or the seal may be damaged and leak. The pulley cannot be tightened past the limits as it only has one bearing and will wobble with an over tightened belt and cause the grease to turn to oil from the heat and cause the two independent seal halves to slide from side to side. Those are probable causes. System oil added to the compressor can also do this.
Hope this helps and that others far more knowledgeable then me chime in here.
Belt screeching may be an indication of a bigger problem .. possible over oil or over gas. On a factory A6 The belt should have 3/4" up and 3/4 " down or the seal may be damaged and leak. The pulley cannot be tightened past the limits as it only has one bearing and will wobble with an over tightened belt and cause the grease to turn to oil from the heat and cause the two independent seal halves to slide from side to side. Those are probable causes. System oil added to the compressor can also do this.
Hope this helps and that others far more knowledgeable then me chime in here.
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
Thanks! There was at least twice the deflection you mention. So after thightening the belt the screeching was gone.
Thread Starter
Racer
Joined: Aug 2004
Posts: 442
Likes: 185
From: Zürich Switzerland
2026 Corvette of the Year Finalist - Unmodified
2025 C2 of the Year ('64-'66) Winner - Unmodified
A/C hoses - press fit necessary?
Back at the shop the owner says that with these old-style clamp hoses the system will leak for sure and that I need to replace them with press fit ones.
What do you guys think? My hoses look fairly new.
Unfortunately the compressor seal is leaking. So I need to adress that anyway.
What do you guys think? My hoses look fairly new.
Unfortunately the compressor seal is leaking. So I need to adress that anyway.
Race Director
Joined: Mar 2002
Posts: 13,633
Likes: 3,580
From: NorCal
Racer
Joined: Jun 2013
Posts: 337
Likes: 27
From: Fremont CA
Just some advice, if the freon is overcharge can cause problems with the high side if the system get's too hot. This could result in a big green spray of green die on the the passenger's firewall from the compressor's relief valve on the back. Also, take a white cloth and try wiping down the pulley or above inside hood to see if you find any die. This could be the start of a leaking seal for the pulley. I also added two 8" electric push fans in front of the condenser as another precaution. It's pretty to add by tapping on to the wire going to the compressor pulley clutch as a negative relay trigger.