How to pressure test the A/C unit. Part 1

This is the first in the series on refrigerant leak detection. The pressure test.
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.

28 Replies to “How to pressure test the A/C unit. Part 1”

  1. I located two leaks just today using nitrogen and an accutrak vpe, also found one leak yesterday using the same method. Discovering these leaks only took a few minutes, they were quite obvious.

  2. Oh man finally this is the cleanest explanation of pressure the system on entire youtube thank you sir.

  3. Hi Thanks for the video..I have a leak in a heat pumps system with TXV in both . I'm going to isolate the units. Do i need to pressurize both high and low sides of the line sets or just one side?
    Thanks in Advance

  4. Thanks very much sir for your good work. Also sir given that we now have nitrogen in the unit, how are we going to get it out before our refrigerant recharge? Thanks

  5. Never ever put 700 Psig on any hvac system. The compressors aren’t meant for any more than 150 psig.

  6. To add to my other comment, a compressor can only take so much pressure before it will be dangerous and could potentially explode and could kill someone. So he says it could go to 700psi, no system works at that pressure. It’s not made to at all, not even close to that. So at about 420-450psi, the compressor could start to expand/change shape due to high pressures therefore damaging the compressor. Above 450psi, this will be when the compressor could be explosive. Please please please take my advice and only pressure test at 150PSI MAX!!

  7. Please don’t listen to this guy. Pressure testing a unit at 700psi will definitely cause the compressors to explode. It will break right at the weld joint where the cap is. This is very dangerous. Pressure testing should only be at 150lbs MAX.

  8. cut the bottle off and use the pressure gauge on the bottle to see if your loosing pressure ,,you don't need the gauges,,jut don't loosen the hoses

  9. if you are pressure testing with nitrogen do you really need to bleed the lines, because when your done testing you are going to release the charge

  10. After you finish the leak test…do you recover the nitrogen with a recovery machine or what..?

  11. Very good video. I have a question that I am having trouble finding an answer to. The question is how many ounces of liquid refrigerant will a standard 1/4" refrigerant hose hold per foot? And is there much variance between refrigerants? I have search online to no avail. Thanks.

  12. I have a question relating to the installation of a 2.5 ton R-410 split a/c system that comes with a precharged condenser….how does one purge for brazing or pressure test the interconnecting tubing with nitrogen when there are no service ports on the evaporator?

  13. Is it possible to presurrize two units at the same time using one set of gauges on a 410a system?

  14. I followed you right up to the end of the purging of the hoses to the input of the unit and this is where I've always parted company with some of you guys demonstrating this procedure.
    Correct me if I'm wrong, I don't want to be the contrarian here, but the way I see it, you're simply applying a pressurized column of Nitrogen to the input of the unit and compressing the air within, because the opposite side of the system (low or high depending on which way the flow is) is closed, UNLESS, you purge the system and lines by applying pressure (as you are doing) and then loosening the opposite attached hose to purge, OR, you first pull a vacuum and then introduce the nitrogen.

  15. on a R-410a system, will nitrogen be good with the refrigerant oil when you do the leak test passing tthru the compressor?

  16. Thanks for the video. I need to pressure test a r22 260tr chiller evaporator shell, the tubes hv refrigerant In them. How much should be the nitrogen test pressure be for the same?? The design working pressure for tubes is 235psi and shell is 150psi.

  17. How many ounce of r22 do you put in unit if you do have a leak, to be able to use leak detector?

Comments are closed.