can you overfil the ac?
Thread Starter
Safety Car
Joined: Jun 2002
Posts: 4,135
Likes: 1
can you overfil the ac?
i was toping off my a/c in my 1973,when i shut off the car i heard a hissing, the freon was leaking from the dryer, i turned the car on again and it stopped, can you over fill it? or is my dryer shot?
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Absolutely. After having my home evaporator coil replaced a few weeks ago on a ~55* day, upon my report that it wasn't cooling optimally once the heat arrived, the technicial found the system a bit "over-charged". Best to do these things at above 70* ambient, was his comment.
Agree you need the gauges, and I'd speculate the dryer is shot.
Agree you need the gauges, and I'd speculate the dryer is shot.
Le Mans Master
Joined: Jun 2007
Posts: 7,666
Likes: 1
From: Where it's always hot as Hell-South Louisiana.
St. Jude Donor '07-'08-'09-'10-'11-'12-'13
1. you should use gauges to test the fill charge.
2. the "hissing" you hear is normal as the system "equalizes" once the compressor shuts down. The only way to test the drier is to find a deltaP across it while operating-using gauges.. If you mean a leak check, dawn liquid will tell a leak right away.
I assume you meant the refrigerant is leaking out the system, if so, use the dawn to find where and replace/repair then vacuum then recharge. If you meant only the noise, thats normal.
2. the "hissing" you hear is normal as the system "equalizes" once the compressor shuts down. The only way to test the drier is to find a deltaP across it while operating-using gauges.. If you mean a leak check, dawn liquid will tell a leak right away.
I assume you meant the refrigerant is leaking out the system, if so, use the dawn to find where and replace/repair then vacuum then recharge. If you meant only the noise, thats normal.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Absolutely you can overfill it. R134 is especially sensitive to charge. Too much and the high side goes really high, you can blow hoses and other nasty stuff. You need a gauge set to do a/c work or you really are just taking a shot in the dark with the "suicide kits".
Instructor
Joined: Feb 2010
Posts: 118
Likes: 0
From: Ok
Sounds like it was just equalizing out. But you can over charge and it will not cool as good. Alot went by charging with ac blowing max and slow filling and waiting a few minutes between "burst" charges for it to equal out. When the low side lines start to condensate your usually pretty close. But always better to do it right with a set of gauges.
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
Racer
Joined: Jun 2006
Posts: 476
Likes: 0
From: Easton PA
1 oz. a/c dye run system 'charged' use black lite over whole system and you will see leak. sometime can be seem were 'pag oil' built up externally and now dirt collected on it. absolutly need a/c manifold gauges with correct charge amount per year vette.
Tech Contributor
Joined: Aug 1999
Posts: 14,365
Likes: 6,345
From: At my Bar drinking and wrenching in Lafayette Colorado
Carl -
Yes, you can over-fill an AC system. What happens is that the high side pressure will run high and the system loses efficiency.
The hissing you hear after shutdown is normal - you are hearing the high side pressure bleed through the expansion valve to equalize high and low side.
If you suspect a leak, just spray some Windex at the joints and suspected leak areas - it will bubble up immediately if a leak is present. AC system components will not start leaking from a slight overcharge.
The 1973 system should have a high side sight glass so you can actually "see" when you have a fully charged system, whether you use gauges or not. Once the bubbles disappear and the sight glass flows clear, the system is charged and should not be charged further.
Lars
Yes, you can over-fill an AC system. What happens is that the high side pressure will run high and the system loses efficiency.
The hissing you hear after shutdown is normal - you are hearing the high side pressure bleed through the expansion valve to equalize high and low side.
If you suspect a leak, just spray some Windex at the joints and suspected leak areas - it will bubble up immediately if a leak is present. AC system components will not start leaking from a slight overcharge.
The 1973 system should have a high side sight glass so you can actually "see" when you have a fully charged system, whether you use gauges or not. Once the bubbles disappear and the sight glass flows clear, the system is charged and should not be charged further.
Lars
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
It really depends on how you charge it. If you use a high pressure refrigerant tank as a source then you must use gauges to determine the high pressure side of the system and stop filling when it reaches max. If you use the off-the-shelf cans available at parts stores then it's unlikely that you will be able to overfill.
I filled my stock 75 A/C system with the off-the-shelf cans and simply hooked them up to the low-side fitting and let the system take what it wanted...worked for me and got 45ºF out the vents. If you are concerned about leaks then try the dye & blacklight. You should also take it to a shop and have them evacuate the system and put a vacuum on it and see how long it holds. And, you might also want to have them flush the system to get all the oil out. When I had my system flushed they found almost 12oz of oil in the condenser from when the previous owner kept adding more cans that included an oil charge. With so much oil in the system there wasn't enough room for sufficient R12 to provide decent cooling.
I filled my stock 75 A/C system with the off-the-shelf cans and simply hooked them up to the low-side fitting and let the system take what it wanted...worked for me and got 45ºF out the vents. If you are concerned about leaks then try the dye & blacklight. You should also take it to a shop and have them evacuate the system and put a vacuum on it and see how long it holds. And, you might also want to have them flush the system to get all the oil out. When I had my system flushed they found almost 12oz of oil in the condenser from when the previous owner kept adding more cans that included an oil charge. With so much oil in the system there wasn't enough room for sufficient R12 to provide decent cooling.
Last edited by Rockn-Roll; Jul 6, 2010 at 12:37 PM.
