Paging HVAC Gurus, HELP!
Paging HVAC Gurus, HELP! I removed the freon line from the condensor while replacing the radiator on the wife's T/A, now I need to recharge the system. Do I need to pull a vacuum on the system first then and add oil with the freon? If so, how much of a vacuum? I just got a nice A/C gauge set/manifold; will this tell me when I've pulled a high enough vacuum? Someone made a post a while back on how they used an old refrigerator pump to pull the vacuum, but the search function is giving me no love! TIA!
Re: Paging HVAC Gurus, HELP! OK I found the thread, it's here if anyone else would like to see it:https://ls1tech.com/threads/showflat...true#Post15382
I'm still interested in any comments on performing this operation, though. I'm wondering if a 12 volt portable air compressor could be used to pull the required vacuum?
I'm still interested in any comments on performing this operation, though. I'm wondering if a 12 volt portable air compressor could be used to pull the required vacuum?
Re: Paging HVAC Gurus, HELP! You need to pull a vacuum of at least 29 inches, turn off the vacuum pump, and make sure it holds for a few minutes. Then, refill with 134. You need to borrow a good vacuum pump for this.
Re: Paging HVAC Gurus, HELP!
You need to pull a vacuum of at least 29 inches, turn off the vacuum pump, and make sure it holds for a few minutes. Then, refill with 134. You need to borrow a good vacuum pump for this.
Re: Paging HVAC Gurus, HELP!
I prefer a vacuum pump and a micron gage, moisture and air are bad for any system
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Teching In
Joined: Jul 2002
Posts: 24
Likes: 0
From: Right Coast, USA
Re: Paging HVAC Gurus, HELP! You only need to add oil if oil came out with the refrigerant when you opened the lines. When you normally empty a system you use a hose attached to a charge port and you measure the amount of oil that comes out with the freon. You do not want to add too much oil to the system.
You need to pull a vacuum of at least 28 inHg for at least 30 minutes to pull the moisture out of the system. After pulling a vacuum for 30 minutes close all gauges and make sure the system holds the vacuum for at least 10 minutes. If the system holds hook a Freon source to the middle manifold line, purge the line of air, and then start to charge the system. Do not overcharge the system.
You need to pull a vacuum of at least 28 inHg for at least 30 minutes to pull the moisture out of the system. After pulling a vacuum for 30 minutes close all gauges and make sure the system holds the vacuum for at least 10 minutes. If the system holds hook a Freon source to the middle manifold line, purge the line of air, and then start to charge the system. Do not overcharge the system.
Teching In
Joined: Jul 2002
Posts: 24
Likes: 0
From: Right Coast, USA
Re: Paging HVAC Gurus, HELP! I use this vacuum pump:
http://www.harborfreight.com/cpi/cta...temnumber=3952
I got it on sale for $10
http://www.harborfreight.com/cpi/cta...temnumber=3952
I got it on sale for $10
On The Tree
Joined: Feb 2003
Posts: 178
Likes: 0
From: grimsby, ont. can.
Re: Paging HVAC Gurus, HELP! just go to the dealer or good shop and get them to pull vac. All you got to do is add the 134-a. Saves on the run around and headache if you did it right or not. What are your plans on the pump if you buy it after you pulled vacuum anyway?
Teching In
Joined: Jul 2002
Posts: 24
Likes: 0
From: Right Coast, USA
Re: Paging HVAC Gurus, HELP!
just go to the dealer or good shop and get them to pull vac. All you got to do is add the 134-a. Saves on the run around and headache if you did it right or not. What are your plans on the pump if you buy it after you pulled vacuum anyway?
The system should be charged immediately after the vacuum procedure is completed. The tech that pulls the vacuum should also do the charge.
Re: Paging HVAC Gurus, HELP!
Checked the price of 134-a at work and it is $13 a pound. That's Canadian of course. So, that is something like $5 American or cheaper? 
I paid about $4 each for two 12 oz cans; that seemed to be the perfect amount for my '93 Fbody. Re: Paging HVAC Gurus, HELP!
I use this vacuum pump:
http://www.harborfreight.com/cpi/cta...temnumber=3952
I got it on sale for $10
http://www.harborfreight.com/cpi/cta...temnumber=3952
I got it on sale for $10
Re: Paging HVAC Gurus, HELP! OK I just finished up this job and it's working like a champ, pumping out tons of freezing air! 
Many thanks to all that responded to this thread, knowledge is good! 
The Details: I wound up building an adapter hose to connect the input of my shop compressor into my gage manifold. I was able to get 21"Hg this way, which is a little short of what I wanted, but the system is working well. Next time I'll get a real vacuum pump. It held the vacuum without any perceptible drop for 15 minutes, so I added 2ozs of PAK oil, two cans of R134a and ended up with 33 psi on the low side and 165 psi on the high side at an ambient of 80*F. The shop manual called out 25psi/178psi @ 85*F.
Many thanks to all that responded to this thread, knowledge is good! The Details: I wound up building an adapter hose to connect the input of my shop compressor into my gage manifold. I was able to get 21"Hg this way, which is a little short of what I wanted, but the system is working well. Next time I'll get a real vacuum pump. It held the vacuum without any perceptible drop for 15 minutes, so I added 2ozs of PAK oil, two cans of R134a and ended up with 33 psi on the low side and 165 psi on the high side at an ambient of 80*F. The shop manual called out 25psi/178psi @ 85*F.
