How to pump down the air conditioner

This one covers procedures to pump down the air conditioner into the condensing unit. This video is part of the heating and cooling series of training videos made to accompany my websites: and to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.

16 Replies to “How to pump down the air conditioner”

  1. I was doing a pump down today. But around 2 or 3 seconds into the pump down the compressor went off. I tried again and same thing. I see that there are no low or high pressure sensors on the copper pipes that can cause compressor to turn off. Thanks

  2. Thank you for another fine video.

    I've set up a separate folder for "HVAC gasses".
    For some reason, this part of HVAC has a lot of trees but not enough forest.
    I've seen other videos where they immediately start tossing around jargon and assuming concepts and I think "if you understand this guy, you don't need need this instruction, so what are you doing here?"

    In this video, I'm drawing a blank about "why are we here? Why do we need a "pump down". What IS a "pump down?" Some diagrams/visual aids might be helpful.

    Again, GFM's videos are always better than most and often the best of the category.
    Thank you.

  3. Ok so I shut the power off.connect my manifold gauges to high and low with my manifold gauges closed.turn liquid line clockwise. Manually start unit by pushing contact when gauges are at 0 do I also turn the suction line clock wise?…and once I have turned it clock wise when I remove my gauges can I cut the lines and cap them? I'm trying to relocate a ac unit

  4. Only units I have issues doing this on are the Trane / American Standards. They will usually trip the internal pressure relief before full pull down. One thing that helps is I use a ratcheting allen wrench. I don't fully close the high side. Then as the suction drops to lower pressure I then fully close the high side.Still may have to recover a little. Pumped down literally hundreds of unit but won't lie…you cringe hearing the compressor make its noises towards the end of the pumpdown

  5. if you pump it down to repair a leak that require brazing, it usually not good to leave any refrigerant in the lineset as you brazing. i wouldn't worry about the atmospheric pressure getting inside the line, i would simply pull a vacuum to 500 micron which you are suppose to do any way.

  6. Now I have a 2006 Carrier condenser with a low and high pressure limit switch. Will I still be able to do a pump down manually holding the contactor in

  7. Looks like a nice tidy install also is that an un lagged liquid line I see there ? Also getting oxygen in the suction line isn't a big deal as you made out the system always needs to vacced out to remove any moisture or oxygen after pipe maintenance.

  8. sir, I tell you it would have beeb nice to had you for a instructor 25 years ago you are great I will continue to watch your videos. THANKS!

  9. Thanks, it would be great if you showed some videos about very short and very long line set applications.

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