How To Pull a Vacuum on Car's A/C System -Jonny DIY

How To Pull a Vacuum on Car's  A/C System -Jonny DIY

Oh Deb youtubers John a DIY here today I'm going to be showing you guys how to pull a vacuum on your car's AC system and what you're going to need for this is a set of AC manifold gauges and a vacuum pump I rented both of these at my local autozone first things first is we're going to set up the manifold gauges through the red hose down here on the bottom of the red set screw the blue hose and then the blue side I'm going to screw the yellow hose on right in the middle no you got these little connectors these are going to snap into our high and low sides on our AC system and we'll put the blue one right on the end of the blue hose and this red one right on the end of the red house go ahead and hang this up here we go now our yellow line right here this is going to run down it's going to screw right down on the top of our vacuum pump screw that up now we got to put these on the high and low sides of our AC lines on this car the high sides right here and this snaps on you can't worry about getting these mixed up behind low side these will only fit on the high and low side ports so you can't get them mixed up if you have trouble finding needs to AC lines this is your AC condenser right here in the front and the AC lines will be coming out usually one on each side and you can just follow these lines to find the ports and the forks usually have these little caps here's the low side over here on the left snap that on on okay now you want to make sure that these are in the open position so on these you turn clockwise to open these ones right here yep okay now on I gauges here we want to make sure these are closed and these just turn regular clockwise will be too close make sure these are closed to start out work okay so this vacuum you can you're going to do this to check to see if you have a leak will vacuum then we'll hold the vacuum and if it holds that pressure that means there's no leak in the system but also you need to do a vacuum on your system if you're going to recharge it and all of your refrigerant is out because you can't have any air in the system so here up here are gages little green part right here from 0 to 30 that's going to read our vacuum so now we go ahead and turn on our little Ghostbusters ghost catcher now it totally looks like it okay now we're going to open both the low and high side of these valleys are open all the way now if you look at the gauge it's going down to 30 and it should be around 29 or 30 pounds of inches of mercury you should be able to hold about 29 or 30 and that'll mean it's got a good good vacuum but if you can't even hold 29 30 vacuum that means you definitely got a big leak all right now once you got at 30 if you can get to 30 we're going to go ahead and close these off both of them getting tight and we can turn off our vacuum pump now the system is under vacuum and what we're going to want to do is we're going to want to let this set for about an hour and we want this to keep at 30 right here that'll mean it's holding the vacuum and there's no leak all right in an hour and it's still holding 30 where it was when I first closed it so that's a good sign so that means it's not to leak in anything out of the vacuum and so now I know how many leaks so if you were going to recharge the system you're going to want to go ahead and run your vacuum for about 30 minutes to an hour to get all the air out then you can connect your refrigerant to this yellow line and add that to your system and then you can read it right here on the low side all right and that is how to vacuum your AC system out guys guys like this video give it a thumbs up for me a comment like check out my other videos that really appreciate it thanks for watching Johnny DIY keep on doing yourself day


  1. What if my ac system still has refrigerant in it but I want to pull a vacuum to get all the air and moisture out so it can run colder than it is? Do I need to evacuate all the perfectly good refrigerant out first? I imagine a vacuum pump won’t only pull air and moisture out but also refrigerant along with it.

  2. I do not understand keeping the valves on the gauge manifold closed. If you close them, aren't you just seeing the vacuum in the gauge manifold? I would think you would want to leave the valves open… maybe close them, connect the yellow hose back to the manifold tightly, then open the valves again to be able to see if the vacuum is holding in the car's ac system. I guess I do not understand what the valves are opening/closing. Do the gauges always show what is going on on the hoses? Do the valves just control the opening to the yellow hose?

  3. Got the vacuum hooked up now. Just replaced the condenser and dryer. My compressor was replaced when I thought that was the problem last year. (It wasn't)
    The hardest part is waiting the first half hour to hour to make sure no leaks.
    Also it's mist coming out of the vacuum most likely.

    All in all you video had the info I was looking for.

    Now I have to go reinstall the grill and brush guard

  4. Nice video! But my system won’t go down below zero but it holds a vacuum ? It’s about 4 notches above 0. Can I add Freon ?

  5. Hey quick question. So after I know i dont have a leak. I turn the pump back on for a few hours. And then what do i do?

  6. I did not understand this video. He says if it gets to 30, you can close it now and turn off the vacuum. Now its going to vacuum for 1 hour. So how is it going to vacuum with vacuum off?

  7. I have honda city 2005 exi model.. When I teun on the A/c rpm goes down below 600..enigne pick up is very low…….

  8. Hi Jonny. Great video!!! I'm going to be replacing my compressor on my 08' Honda CRV. This is the machine I need to rent from Autozone to vacuum out the freeon & air out of the system before disconnecting the lines right? And when I replace it vacuum any air in the lines before charging it up with freeon right? Just want to be have more knowledge when I go to do it. Thanks!!! Hope to hear back from you

  9. Sorry, I don't get it. When you turn of the valves on the manifold…have you not ceased to measure "vacuum" in system…no matter how long you wait?

  10. Can I do this on a semi charged system? Or do I have to have all the R134a out of the system. I accidentally got air into the system and my ac is just barely cool. The compressor is running and the fuse is good as well.

  11. Thanks for video Jonny. I've tried pulling vacuum on a 2005 odyssey after changing compressor. The low side gauge would not move at all. What am I doing wrong. Please help

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