A/C Lines disconnected overnight - Do I really need to Vacuum?

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Wow, great info everyone!

Thanks Gerald. If my neighbor doesn't work out I'll take you up on it.

I went searching for a compressor and I see a guy in the neighborhood painting a car fender and hood with a paint gun. So I stop in and strike up a conversation. He's fixing his daughter's fender bender. He's a self-employed HVAC guy and owns an 1969 AMX!

Any how, he's got a pump and gauges, and agreed to help evacuate the system, and he mentioned using nitrogen as a way to confirm there are no leaks and then vacuum that out before charging.
 
Pulling" is not the word I would use. The very reason we used to call it a "sweep"
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This could be po-tay-toes vs po-tah-toes; but with sweep charging you are using refrigerant to sweep out or push out air & non-condensables from the hi-side to the lo-side and suction service port. The amount of time to accomplish this and assure no non-condensables is a judgement call and then right to charging the spec'd charge. Pulling is using a vacuum pump to pull or pump out to a vacuum, THEN add the charge. Either one can work, but I wouldn't trust sweep charging with today's critical charges and sponging, or some call the blotter method, is compliant if you're in to that.
 
66fyssh said:
Wow, great info everyone!

Thanks Gerald. If my neighbor doesn't work out I'll take you up on it.

I went searching for a compressor and I see a guy in the neighborhood painting a car fender and hood with a paint gun. So I stop in and strike up a conversation. He's fixing his daughter's fender bender. He's a self-employed HVAC guy and owns an 1969 AMX!

Any how, he's got a pump and gauges, and agreed to help evacuate the system, and he mentioned using nitrogen as a way to confirm there are no leaks and then vacuum that out before charging.
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Dang would like to have seen your car!

I would have made you pull it over as well! Missed seeing you in D'ville Memorial Day weekend we brought home some hardware!
 
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1969383S said:
Dang would like to have seen your car!

I would have made you pull it over as well! Missed seeing you in D'ville Memorial Day weekend we brought home some hardware!
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CONGRATS!! You have an awesome car!

We ended up doing the trip south on Friday to drop off my grandson and again on Monday to pick him up. I was free on Saturday but until I start working I really need to conserve funds!! We'll connect soon! And...I had 3 phone interviews today with 3 different people at the same company. It's for a recruiter position placing people getting out of the military into service technicians jobs at a couple of luxury import car makers. I'm stoked!!!! Just keeping my fingers crossed to move forward.
 
66fyssh said:
CONGRATS!! You have an awesome car!

We ended up doing the trip south on Friday to drop off my grandson and again on Monday to pick him up. I was free on Saturday but until I start working I really need to conserve funds!! We'll connect soon! And...I had 3 phone interviews today with 3 different people at the same company. It's for a recruiter position placing people getting out of the military into service technicians jobs at a couple of luxury import car makers. I'm stoked!!!! Just keeping my fingers crossed to move forward.
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Best of luck! Got my fingers crossed for you!
 
greg r said:
This could be po-tay-toes vs po-tah-toes; but with sweep charging you are using refrigerant to sweep out or push out air & non-condensables from the hi-side to the lo-side and suction service port. The amount of time to accomplish this and assure no non-condensables is a judgement call and then right to charging the spec'd charge. Pulling is using a vacuum pump to pull or pump out to a vacuum, THEN add the charge. Either one can work, but I wouldn't trust sweep charging with today's critical charges and sponging, or some call the blotter method, is compliant if you're in to that.
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You have COMPLETELY missed my point. I'm saying that whether you use N2, CO2, or refrigerant to sweep charge, you USE it in such a way as to sweep and push out impurities, and THEN evacuate. In other words you don't simply pressurise the system and then evacuate.
 
66fyssh said:
Hey guys, I replaced the heater core in my 2008 Tundra and had the A/C lines disconnected overnight while the truck was parked in my garage this past winter.

It's getting hot in Georgia now and I'd like to recharge but I don't have a compressor. Will it hurt not to vacuum the system? Thanks!
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Some people believe that if the receive dryer has been exposed to air that it would be too saturated to vacuum all the air/moisture from it. I personally never had an issue with not replacing one but always advised on possible trouble down the road. If it was car, evacuate and charge. Make sure you add oil (lube the components) and dye (see any future leaks) to it.
 
Ferdinandbites said:
Some people believe that if the receive dryer has been exposed to air that it would be too saturated to vacuum all the air/moisture from it. I personally never had an issue with not replacing one but always advised on possible trouble down the road. If it was car, evacuate and charge. Make sure you add oil (lube the components) and dye (see any future leaks) to it.
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Also, just a thought, if there is an orifice tube in that thing, especially if you bolw it out, replace it. I've had that thing cause some crazy freezing in the line.
 
I usually replace the dryer if I open the system for more than an hour or two. Pulling a hard vacuum afterwards is the right thing and how long depends on the ambient temps and more. 4 hours or more is always good! The longer it is in vacuum the easier the moisture will boil right out! Recharging is better and quicker as well!
 
The PAG oil normally used w/ R-134A absorbs moisture from the air and forms acids that can eat thru an aluminum condenser. People that experienced that usually had the system open for a year. One day isn't a big deal, especially if you thought to seal the tube ends w/ a plastic bag and rubber band. I have hooked to manifold vacuum to get down to 20"HG, then switched to a Mighty-Mite hand pump to get down to 29"Hg, after ~10 min pumping. That is better than nothing, and probably good enough on our 110 F days w/ sun on the engine to drive out any water. But, since I bought the Harbor Freight vacuum pump on sale. It is kind of neat that you can hear when the pump is moving air & vapors. Eventually when it gets quiet you are at almost pure vacuum. Some AC shops then fill w/ pressurized nitrogen, then blow that off to sweep anything out, and vacuum again.

In the old days, we would vent R-12 to sweep out any moisture. But, freon was $0.20/can then and they sold BB machine-guns that used the cans. Today, venting to atmosphere is illegal, even for the HC refrigerant I use (Duracool, Envirosafe) that is no worse than a cow fart. The "ozone hole" is still a claimed concern and R-134A is a bad greenhouse gas, soon to be outlawed.
 
I don'no, I think you have to "temper" this with common sense.

"My story.........."

My old 70, a V code 6bbl car had aftermarket "knee knocker" AC. Somewhere around 73? I put a 340 in the car. That in itself is a long story. Anyhow, one day I discovered it would be easy to adapt the compressor bracket off the 440 to the 340. Bear in mind this is aftermarket. The drive pulley was cast iron, just "stacked" on top of the rest. So I put the "knee knocker" back in the car.

I "swept" the system with a can or two of R12, and USED ENGINE VACUUM LOL to vac the system. It was also HOT so this helped. That system was still running when I sold the car in 76? 77? Yes, it leaked!! Used hose clamps on the fittings.

This blurry old thing was taken soon after the engine went into the car, a 20K junkyard engine. I was BROKE!! (E-5 Navy pay wasn't that much back then!!) This was before the A/C went back in

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Bill, I WISH I would have thought to cap off the ends...

I bought an A/C o-ring kit today to replace the two that I disconnected and plan to get with my neighbor tomorrow to vacuum it with his electric pump. Hopefully he'll be around since I have off work. He also mentioned using nitrogen to check for leaks. It's been REALLY hot here so I need to get it going!!!
 
66fyssh said:
Bill, I WISH I would have thought to cap off the ends...

I bought an A/C o-ring kit today to replace the two that I disconnected and plan to get with my neighbor tomorrow to vacuum it with his electric pump. Hopefully he'll be around since I have off work. He also mentioned using nitrogen to check for leaks. It's been REALLY hot here so I need to get it going!!!
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That's for the larger leaks. Wont show thoses really small ones very well.
 
He also mentioned using nitrogen to check for leaks.
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Works pretty good with soap bubbles. If you want to find small leaks, put a couple of ounces of refrigerant in with the N2 for a trace gas, I like R22 for example. An electronic sniffer can really vet out the leaks then. Using barrier hose on your gauge set will cut down false leads. Mechanical compressor seals will also "leak" a tad until things get moving and the seal is bathed in oil.
 
Thanks again everyone! I had never done anything more than add refrigerant before so this was a learning process.

My neighbor came today. I had already changed the o-rings. He ran his electric pump for about 20 minutes and it was right at 30 inches. Then he added nitrogen to 100 psi. We waited about 10 minutes and the gauge didn't move. Then released the nitrogen and ran vacuum for another 20 minutes back to 30 inches. I added the refrigerant and waited some more keeping an eye on the high side pressure. No change. A/C is running cold. Hopefully I'll be running cool for long time!!! (Insert sunglasses emoji) Hey @Joeychgo where is the sunglasses emoji!!
 
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