Re-charging R134 A/C
Thread Starter
Instructor
Joined: Jul 2001
Posts: 189
Likes: 0
From: Berkeley Heights New Jersey
Re-charging R134 A/C
I had my car switched over to R134A last summer and now notice some foaming in the sight glass. I bought a re-charge kit and one can of refrigerant. I hooked it up to the low side as instructed and began to recharge the system. After a short period, I felt the can which by the way I had in an upright position, getting very cold with ice crystal beginning to form on the can. I panicked and disconnected the hoses. I still had about half a can of R134 left, but I was concerned that the can might explode. I don't know if I can leave it connect while it gets so cold and wait for all the gas to enter the system. I still have air bubbles flowing through the sight glass. However, I placed a thermometer at the certer outlet duct and it read 42 degrees. Am I asking for too much and leave it at this point??
Burning Brakes
Joined: Dec 2001
Posts: 1,091
Likes: 0
From: Texas
Re: Re-charging R134 A/C (bl75vette)
bl75,
i just did this yesterday. i got the kit with the gauge. i put the can with the kit in and it too turned to ice. after i put it in i still needed two put in another 12oz can. i was unabloe to see into the sightglass. i think the can turning cold is ok.
Mike
i just did this yesterday. i got the kit with the gauge. i put the can with the kit in and it too turned to ice. after i put it in i still needed two put in another 12oz can. i was unabloe to see into the sightglass. i think the can turning cold is ok.
Mike
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Re: Re-charging R134 A/C (bl75vette)
Not a problem. Sometimes it gets cold enough that it will not transfer well, but cold/ice indicates very LOW pressure. Put in the rest of the can, then let it run a few minutes as you watch the sight glass. It takes a second for the system to equalize pressure and give you a true indication. As soon as you don't see any more bubbles, STOP, your done. Better to be slightly low than over full. Sounds like the rest of that can should do it, since your already @ 42 degrees. remember, check the outlet temp on med. high blower speed (second highest), at around 1200 - 1500 RPM for a true indication of A/C outlet temperatures. Good luck.
Hans
Hans
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Re-charging R134 A/C (bl75vette)
The refrigerant in the can escapes from the can into the system causing the coldness. That's normal. Rapidly expanding gasses get cold. Compressing gasses get hot. That's how A/C works. The compressor compresses the gas and sends it to the condenser (in front of the radiator). It then goes to the evaporator(on the firewall) where it expands and gets cold. Then it is drawn back into the compressor and the cycle starts over.
You really need to use pressure gauges to service the system and know what the pressure are.
You really need to use pressure gauges to service the system and know what the pressure are.
Team Owner
Joined: May 2001
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
CI 6-7-8 Veteran
CI-VIII Burnout Champ
St. Jude Donor '06-'10, '13
Re: Re-charging R134 A/C (Michael Tucker)
The can turning cold is normal, as explained in the post before.
You really should spend the extra $ and get the gages so you know the pressure of the system.
to help some, put the can in warm (not hot) water as you are filling the system. Or continue to run warm water over it.
You really should spend the extra $ and get the gages so you know the pressure of the system.
to help some, put the can in warm (not hot) water as you are filling the system. Or continue to run warm water over it.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Re: Re-charging R134 A/C (BSeery)
With R134a you cannot use the sightglass to check the charge. By the time the sightglass clears you will be way overcharged.
But if your vent temps are 42F, I'd just leave it alone.
But if your vent temps are 42F, I'd just leave it alone.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Re: Re-charging R134 A/C (zwede)
I agree that if you just keep slapping cans to it and watch the glass, it'll overcharge, but if you go slow and let it run a while between cans, it can be used instead of gauges. Eventually, ya gotta fix that leak!
I heartily agree that a set of gauges is the way to go, and it's the only way I do it. You can get a serviceable set for around $150.-, and you can fix up a vacuum pump from an old reefer if you really want to keep it cheap! Otherwise, that's probably the most expensive tool you need, and you would need to do it fairly often to justify the expense.
I'm getting 38 degrees with the POA valve adjusted as you recommended.
Hans
I heartily agree that a set of gauges is the way to go, and it's the only way I do it. You can get a serviceable set for around $150.-, and you can fix up a vacuum pump from an old reefer if you really want to keep it cheap! Otherwise, that's probably the most expensive tool you need, and you would need to do it fairly often to justify the expense.
I'm getting 38 degrees with the POA valve adjusted as you recommended.
Hans
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Melting Slicks
Joined: Jul 2002
Posts: 3,128
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From: Deltona (son of Deland and DAYTONA) FL
Re: Re-charging R134 A/C (bl75vette)
by the way, I've spoken with our certified A/C tech at our college and he says if you're having trouble getting freon in it's ok to turn the can over and run it in as liquid, but not for more than 10 seconds at a time.
I've also put the can in some hot water as I'm charging. Helps get the R134 in a little faster.
I've also put the can in some hot water as I'm charging. Helps get the R134 in a little faster.
