What to use to pull a vacuum on AC system at home

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8950HO

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#1

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Anyone know of an affordable device/contraption you can use at home instead of going to a garage to pull a vacuum on the AC system?

 

90mustangGT

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#2

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None that would even be worth the trouble. A shop probally won't charge much if anything to vaccume the system down.

 

jrichker

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My current vacuum pump is a refrigerator hermetic unit (motor & compressor in one unit). It was a freebe from a local used appliance store. I bolted it down to a piece of plywood & soldered a 1/4" flare fitting on the suction line. It works great, pulls 29" of vacuum in about 10 minutes or less. I have used it several times and have had excellent results.

 

PuterAmI

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The only shop device that will work is a Robin-Aire unit that runs on shop air. Cost is $60. The $15 cheapies do not pull it down far enough to work below 94 degrees ambient temperature.

A place here rents vacuum pumps for $33 a day. I go in and get it on Saturday morning, then take it back on Monday.

I was helping another guy with his A/C and he mentioned his Autozone loans them. None of mine here do.

 

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2002BLGT

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http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952

 

jrichker

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2002BLGT said:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952

Click to expand...

Reports here on Stangnet is that it is a piece of junk and won't pull anywhere near as much vacuum as advertised.

I like my refrigerator compressor, it was free and pulls excellent vacuum.

I have also removed the air filter from my shop air compressor and plumbed a 1//4" copper line to it. It also makes a great vacuum pump, but it is a 60 gallon floor unit & isn't portable.

 

86T-Top

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I have the same set up as Jrichker, it works great. Sucks it down to about 10 mins also.
It's the best free tool I ever made.

Mario

 

PuterAmI

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2002BLGT said:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952

Click to expand...

Okay, I will repeat...

The $15 cheapies do not pull it down far enough to work below 94 degrees ambient temperature.

 

tmoss

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Yep, I have an old refrigerator compressor motor too. They do work very well.

 

rd

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This country boy uses one of the cheapy air powered venturi units to get it as far as it can. Then I swap to a Mighty vac and hand pump to as close to 27 in as I can get. PITA, but it works. I am getting the refrigerator next.

 

tmoss

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A word of advice - if your system has been open for any length of time, the system and dryer have accumulated moist air. The vacuum pump helps remove vapor moisture by pulling the vapor out but it can also remove condensed moisture if you hold the vacuum on the system long enough - how long depends on the amount of moisture present. The vacuum reduces the boiling point of water and cause it to flash off faster into vapor which is then removed by the vacuum pump. It's not a bad idea to leave it on for a few hours or so.

 

PuterAmI

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#12

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rd said:

...as close to 27 in as I can get. PITA, but it works.

Click to expand...

No, it does not work.
Well, unless it is ~118 degrees where you are at sea level.

http://www.robinair.com/new/acsolutions/acvacuum/acvacuum.php

 

Mustang5L5

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#13

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What are you guys using for connections to connect to the a/c system.

I have a good vac pump, but need a way to connect it to the system. Outlet is 1/4npt, so i can install a line and adapt to fittings, but i need the end connector to hook up to the a/c system somehow....either directly or through the charging hoses

 

tmoss

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#14

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Do you have a set of gauges with a manifold? My manifold is set up to pull the vacuum by hooking the vacuum pump to it and then charge the system from the manifold set. See if you can beg/borrow/steal the right manifold set.

 

Mustang5L5

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#15

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I actually do have a manifold set. I need to take a peek at it and see what the setup is. It's still in the packaging.

Btw, I'm using a 1/2hp, 7cfm 2-stage vacuum pump...just need tomhook it up to then system

 

Mustang5L5

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#16

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Ok, all set on the vac pump. Turns out i can already hook it up.

1 more question. Most recommend pulling vac down to at least 500 microns. Those gauges are expensive! Short of buying one, is my only alternative to just use a standard gauge and pull to as close to 30 as i can and let it run for a few hours?

My pump is very good and pulls down to 30 on a standard gauge...but it's not as accurate as a micron gauge

 

tmoss

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#17

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no need for the micron guage, pull it down for a few hours and refill.

 

tmoss

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#18

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also use an old hair dryer blowing on the acccumulator casing - it will raise ambient temp inside and drive out moisture vapor to be vacuumed out more quickly.

 

Mustang5L5

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#19

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Good tip. I had thought about drawing a vac on a warm day after running the engine to help raise temps

 

jrichker

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#20

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The method I use is to get the engine good and warm and then vacuum down the A/C. The extra heat combined with 28.5"-29" of vacuum does a really good job of getting the moisture to vaporize so that it can be vacuumed out.