Auto AC rules of thumb
Posted: Mon May 20, 2024 8:38 am
What rules of thumb exist in Auto AC?
Below are the ones that come to mind for me. What others exist? Please correct the ones posted as appropriate. I can update this first post with corrections and additions as they come up in additional posts. Maybe it can become a sticky/FAQ. Thanks in advance for your knowledge and contributions.
Rules of Thumb
System pressure in PSI equals ambient temperature in F when the system is not being used and has not been used for a while.
Such result typically means system dues not have moisture/air or other contaminant in system. (Is this true just for R134a or also other refrigerants?)
High side pressure when running showing 3x ambient temperature typically indicates a good functioning system.(Is this true just for R134a or also other refrigerants?)
Don't use sealers, "fix in a can" etc. They make a bigger mess to clean up, can mask real symptoms causing a more difficult fix. Use only specified refrigerant, oil, and as appropriate dye.
Vacuum - Standard gauges do not have enough resolution for vacuuming/leak detecting a system. Ideally use a micron gauge to get to and keep 500microns
Pressure testing - don't use compressed air. It can affect the desiccant in the receiver/drier introducing moisture into system. Nitrogen is preferred and then needs to be vacuum evacuated.
What minimum times/pressures do the pros recommend for the following
1) vacuum of ? Microns holding for ? Minutes/hours is considered a leak free system
2) pressure test of ? PSI holding for ? Minutes/hours is considered a leak free system. (Nitrogen is the preferred gas. Don't use compressed air.)
Below are the ones that come to mind for me. What others exist? Please correct the ones posted as appropriate. I can update this first post with corrections and additions as they come up in additional posts. Maybe it can become a sticky/FAQ. Thanks in advance for your knowledge and contributions.
Rules of Thumb
System pressure in PSI equals ambient temperature in F when the system is not being used and has not been used for a while.
Such result typically means system dues not have moisture/air or other contaminant in system. (Is this true just for R134a or also other refrigerants?)
High side pressure when running showing 3x ambient temperature typically indicates a good functioning system.(Is this true just for R134a or also other refrigerants?)
Don't use sealers, "fix in a can" etc. They make a bigger mess to clean up, can mask real symptoms causing a more difficult fix. Use only specified refrigerant, oil, and as appropriate dye.
Vacuum - Standard gauges do not have enough resolution for vacuuming/leak detecting a system. Ideally use a micron gauge to get to and keep 500microns
Pressure testing - don't use compressed air. It can affect the desiccant in the receiver/drier introducing moisture into system. Nitrogen is preferred and then needs to be vacuum evacuated.
What minimum times/pressures do the pros recommend for the following
1) vacuum of ? Microns holding for ? Minutes/hours is considered a leak free system
2) pressure test of ? PSI holding for ? Minutes/hours is considered a leak free system. (Nitrogen is the preferred gas. Don't use compressed air.)