Is a Triple Evacuation Necessary for a Deep Vacuum?
Do you have to do a triple evacuation if you can achieve a deep vacuum by only doing a single evacuation?
Remember that the target vacuum of 500 microns or lower must be achieved before adding refrigerant. This level is not while the vacuum pump is running but after the pump has been shut off and during the standing vacuum test. A standing vacuum test is performed after the vacuum pump is valved off from the system and after waiting at least 10 minutes to see if the micron level in the system rises. If during your single evacuation, you perform the standing vacuum test and you are holding 200 or 400 microns, then you are certainly under the required vacuum level. Remember, the end goal is to achieve a deep vacuum. If you can do this by only performing a single evacuation and you can prove your deep vacuum during the standing vacuum test, a triple evacuation is not needed. Remember that if the vacuum level remains below 500 microns and does not continue to rise, then you have proven that the air, nitrogen, and water vapor have been removed and there are no leaks. The system is ready for refrigerant!
A couple extra tips: Make sure to remove the valve cores and use valve core removal tools. Mount the vacuum gauge as close to the system as possible and as far away from the vacuum pump as possible. Target around 200 to 300 microns while the pump is running and before trying to perform the standing vacuum test.
Check out our book which goes into detail about the vacuum procedure, standing vacuum test, triple evacuation and breaking the vacuum with refrigerant from the bottle or from the system! Use our workbook to test your knowledge! https://www.acservicetech.com/ac-book
Best Wishes, Craig Migliaccio