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Thread: Vacuum Pump

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    Vacuum Pump

    When are you guys replacing your vacuum pump? I can't seem to pull deep vacuums like I used to, even with clean oil before each evac. Could my pump be loosing its abilities?

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    Quote Originally Posted by jwbrager View Post
    When are you guys replacing your vacuum pump? I can't seem to pull deep vacuums like I used to, even with clean oil before each evac. Could my pump be loosing its abilities?
    When was the last time you replaced your hoses? but to answer your question, yes it can.

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    Have you tried a power flush? I saw a guy at a supply house doing the vacuum tests do this. With the pump running he put new oil in the pump intake and flushed it out right away. I suppose it cleans the cylinder out. I have done it on my pump and it does help. I have also taken the pump apart, cleaned all the internal parts with brake cleaner and reassembled with fresh oil which makes it work about like new.

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    Vacuum Pump

    Let's first try to determine what might have changed... (Forgive me, I didn't look at your profile to see your experience level and Tapatalk won't let me do that now that I've started my reply)

    When is the last time you cleaned your micron gauge sensor?

    Have you tried doing a pull down test by attaching only your clean micron gauge directly to your vacuum pump to see what it is capable of pulling down to?

    When you change your oil are you changing it while the oil is hot and immediately after turning off the pump so all particles are suspended?

    You can drain the oil even quicker by running the pump with the drain port open. Place your thumb over top of the pump exhaust to pressurize the oil chamber and force the oil out quickly. Control the pressure to control the speed. Turn the pump off immediately after the stream of oil stops coming out. I don't recall of it was Yellow Jacket or JB who had that method in their literature but it is an approved method to speed up oil changes.

    Have you just recently started doing repairs rather than new installs? It takes longer to pump down a system that has refrigerant logged in the compressor oil. Enabling the CCH can help speed up the evac time in this scenario.

    Are you removing the a schrader valve cores when evacuating? If not then you may need to adjust the valve core depressor in your hose so it fully depresses the valve core. It's faster to evacuate the system without the cores installed.

    Have you recently started using longer hoses? This may make a difference albeit I suspect it would be minor.

    Are you just starting to vacuum down systems now that the weather is getting colder? It will take longer to evaporate moisture when it's cold.

    Is it possible there is more moisture entering the system before evacuating it? Working with an apprentice that didn't know the importance of making sure no drips enter the system and that steam from wet rags counts as moisture?

    Is it that it take longer or that it won't pull down at all? You might have a leak somewhere. I always pressure test with my gauges attached. The same gauges that I use to evacuate. This way I know my gauges don't leak. I've found the sight glass on the gauges can be notorious for leaking. I've found seal tight hoses can be problematic. Ive also found the braze on style piercing service valve can get mushroomed I someone over torques them when piercing the line. This may allow your seal tight hoses to connect but not depress properly. I always flow nitrogen through both hoses to make sure they have a good unrestricted connection to the system before starting the vacuum process.



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    Quote Originally Posted by thatguy View Post

    You can drain the oil even quicker by running the pump with the drain port open. Place your thumb over top of the pump exhaust to pressurize the oil chamber and force the oil out quickly. Control the pressure to control the speed. Turn the pump off immediately after the stream of oil stops coming out. I don't recall of it was Yellow Jacket or JB who had that method in their literature but it is an approved method to speed up oil changes.


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    It was JB. I remember reading that in the manual.
    Can someone please explain to me -
    Why is there never enough time to do it right the first time, but plenty of time to do it twice?


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    Reading manuals???

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    You could send it in for service if it’s worth fixing. Can be a bit expensive and they’ll charge you for the diagnostic and give you a quote for the repair but still usually much cheaper than a new pump

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    Quote Originally Posted by thatguy View Post
    Let's first try to determine what might have changed... (Forgive me, I didn't look at your profile to see your experience level and Tapatalk won't let me do that now that I've started my reply)

    When is the last time you cleaned your micron gauge sensor?

    Have you tried doing a pull down test by attaching only your clean micron gauge directly to your vacuum pump to see what it is capable of pulling down to?

    When you change your oil are you changing it while the oil is hot and immediately after turning off the pump so all particles are suspended?

    You can drain the oil even quicker by running the pump with the drain port open. Place your thumb over top of the pump exhaust to pressurize the oil chamber and force the oil out quickly. Control the pressure to control the speed. Turn the pump off immediately after the stream of oil stops coming out. I don't recall of it was Yellow Jacket or JB who had that method in their literature but it is an approved method to speed up oil changes.

    Have you just recently started doing repairs rather than new installs? It takes longer to pump down a system that has refrigerant logged in the compressor oil. Enabling the CCH can help speed up the evac time in this scenario.

    Are you removing the a schrader valve cores when evacuating? If not then you may need to adjust the valve core depressor in your hose so it fully depresses the valve core. It's faster to evacuate the system without the cores installed.

    Have you recently started using longer hoses? This may make a difference albeit I suspect it would be minor.

    Are you just starting to vacuum down systems now that the weather is getting colder? It will take longer to evaporate moisture when it's cold.

    Is it possible there is more moisture entering the system before evacuating it? Working with an apprentice that didn't know the importance of making sure no drips enter the system and that steam from wet rags counts as moisture?

    Is it that it take longer or that it won't pull down at all? You might have a leak somewhere. I always pressure test with my gauges attached. The same gauges that I use to evacuate. This way I know my gauges don't leak. I've found the sight glass on the gauges can be notorious for leaking. I've found seal tight hoses can be problematic. Ive also found the braze on style piercing service valve can get mushroomed I someone over torques them when piercing the line. This may allow your seal tight hoses to connect but not depress properly. I always flow nitrogen through both hoses to make sure they have a good unrestricted connection to the system before starting the vacuum process.



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    Quote Originally Posted by joemach View Post
    It was JB. I remember reading that in the manual.
    It's JB and it's not to speed up the oil change. It is to remove the oil from the second stage of a 2 stage pump. A gravity drain will only remove about 70% of the total oil in the pump. The power flush described above will remove 100% of the old oil.

    Clean your micron gauge and attach it directly to the pump. You should be able to pull down to 170 or less microns pretty quickly. If it does pull down, the pump is not the issue. If it doesn't pull down, the pump is the issue. I don't know about other brands, but JB has replacement parts available on their website. You will need the serial# of the pump to get a good parts list
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    My pump shaft seal went bad on my jb 10 cfm. Ordered one from amazon for like 7 dollars and replaced it. Works great again.

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    I was having trouble getting the vacuum to pull down so I changed the oil and power flushed it. I used it yesterday on a new 2 T coil and 25' line set. It only pulled down to below 50 microns . . . "only". I got no complaints.

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    What size cfm pump u using?

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    Quote Originally Posted by heating_chicago View Post
    What size cfm pump u using?
    Me, 7 JB Platnum

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    7 cfm jb platinum


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