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AC vacuum pump?

Johann

Johann

Red Skull Member
Joined
May 20, 2020
Member Number
477
Messages
1,149
Loc
Triangle area NC
Looking to buy one for occasional home shop use. Amazon has them for $50 to $300 bucks.

Any suggestions on what is not crap? What specs to look out for in a pump? Bonus points if it can be used on house systems too.

I already have gauges and am 2-3 on successful repairs. Got two more I'd like to do. My air comp is down so the air driven vac I have won't work. It was not a great set up anyway.
 
Harbor freight pump has served me well and I've used it for pulling vaccum on fairly large chambers more than I've used it on hvac systems.
 
refrigerator compressor is what I use
it doesn't get the vacuum low enough to properly boil off water, but you can hackfuck it by heating everything up while vacuuming to drive the moisture out anyways
prolly pulls a better vacuum than the air-line vacuum ejector style, anyways
 
Ive done two systems in recent years. Both times I just borrowed one from Autozone. I plan on buying one from HF someday.
 
Thanks all! I've gone with a cheapo from Amazon since I had some other stuff I wanted from there too. Fridge compressor sounded interesting but I didn't want to McGyver something.

We will see how well it holds up... For 60 bucks I'll be happy if it works twice

Allegedly 1/3 HP 4CFM pump
 
I use one of these every day:
2036480?$xlarge$.jpg


Some years ago it crapped out, so we bought two China specials from Amazon, like the one you listed. They were both junk, and never pulled a hard vacuum.

Bottom line, get a gauge on it right away before the return window closes.
 
Johann said:
Thanks all! I've gone with a cheapo from Amazon since I had some other stuff I wanted from there too. Fridge compressor sounded interesting but I didn't want to McGyver something.

We will see how well it holds up... For 60 bucks I'll be happy if it works twice

Allegedly 1/3 HP 4CFM pump
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I went with a similar pump last August when redoing my AC. I think it was a $70 pump pretty damn similar to what you got. I had to pull vacuum for a long time, longer than what the instructions said. It did pull vacuum eventually though. AC has been working fine since then.
 
[486] said:
refrigerator compressor is what I use
it doesn't get the vacuum low enough to properly boil off water, but you can hackfuck it by heating everything up while vacuuming to drive the moisture out anyways
prolly pulls a better vacuum than the air-line vacuum ejector style, anyways
Click to expand...
This is also what I've used for years. I even had a vacuum gauge hooked up to one to see how low it could get - pulled down to 25Hg and held that for over four years.
 
Oh, something with the cheapass vacuum pumps;
Change the oil if you want high vacuum!

Run the crappy oil it comes with for break-in, but flush it out before you go hunting a real high vacuum figure.
The oil is somewhat in the vacuum side, and if it is offgassing its volitiles you'll never get lower vacuum than the oil's vapor pressure.
 
Stuck said:
Ive done two systems in recent years. Both times I just borrowed one from Autozone. I plan on buying one from HF someday.
Click to expand...
Borrowing one from the auto parts store was going to be my suggestion as well. If you don't have a need for one every week, or even every month, borrowing one for free from the auto parts store is the best option, IMO.
 
skyhiranger said:
Borrowing one from the auto parts store was going to be my suggestion as well. If you don't have a need for one every week, or even every month, borrowing one for free from the auto parts store is the best option, IMO.
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That's probably a local thing.
 
I've used one of these the past 10+ years without issue. Either be cheap, or drop coin. Buy a new motor or compressor as well

image_26377.jpg
 
skyhiranger said:
Borrowing one from the auto parts store was going to be my suggestion as well. If you don't have a need for one every week, or even every month, borrowing one for free from the auto parts store is the best option, IMO.
Click to expand...
Its not really the best option. They dont always have it in and they dont always have all the parts its supposed to. I gave up and bought one off amazon.
 
TRINDU said:
I've used one of these the past 10+ years without issue. Either be cheap, or drop coin. Buy a new motor or compressor as well

image_26377.jpg
Click to expand...
I have one. At 4cfm, that would be rough on an air compressor if running for an hour or so. Want one? I have one sitting on the shelf that is getting trashed.
 
Stuck said:
Its not really the best option. They dont always have it in and they dont always have all the parts its supposed to. I gave up and bought one off amazon.
Click to expand...
Exactly. My oriellys guy said yeah we got those. I get there and they were like we got gauges. I said gauges ain't no good without a vac. Plus they were a bit over $100 more than HF and that was the better pump
 
I just bought a 12 cfm 2 stage Mastercool pump for mobile systems to replace my older 3 cfm single stage one. Time is money and if I don't need to spend as much time pulling a system down to 500 microns I can justify my higher hourly rates.
 
1oddtech said:
I just bought a 12 cfm 2 stage Mastercool pump for mobile systems to replace my older 3 cfm single stage one. Time is money and if I don't need to spend as much time pulling a system down to 500 microns I can justify my higher hourly rates.
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Makes sense to spend the money for the pro grade stuff if it's used everyday.
 
Yeah the one I bought is for that one year or two need to fix the AC or the random need to pull something to fix something else. I spent about $150 for guages and pump and it works pretty damn well.
 
Stuck said:
Yeah the one I bought is for that one year or two need to fix the AC or the random need to pull something to fix something else. I spent about $150 for guages and pump and it works pretty damn well.
Click to expand...
Same.

I have A/C on only a few things. It's nice in my Bobcat, it's an oven in there with the engine and hydraulics more or less under my ass and on my back.

When I went to use it this year, the pump was cycling. Weird too cause it's worked fine for 20 years. I had to put a new blower motor in it this winter, so maybe something with me doing that. I know I have to pull the cab back up and the blower as it doesn't blow worth a shit now. All the old foam and sealing tape crumbled apart and I didn't feel like messing with it at 10*

Anyhow, calling around and either didn't want to touch it or would be at least an hour to look at it plus $$$ to charge it if that's all it needed.

I added a bit of refrigerant I had on teh shelf from some time back and it's fixed. Cost... maybe $4.

I did have a unit on A/C in cars as well as refer trailers in school but I barely remember it. Just enough that I can charge stuff and know sort of what I'm doing :laughing:
 
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