Automotive Air Conditioning Information Forum

Hello All, Have a R134 system (2004 Jeep) that vacuumed down to 1000 Microns. Closed valves and after 20 Minutes, rose to 1500 Microns. Any input on the result would be appreciated. Nitrogen pressure test showed High-side valve-core and suction line leaking.

It is normal for some outgassing to raise the micron level at first, so pull it back down below 1000 & try again.

Check your service valve hardware, hoses & manifold set for leaks as well.

All of this assumes you corrected the suction hose leak you mentioned.

This is exactly the reason I state a 30 minute vacuum is useless. As suggested, keep the vacuum going for a longer period of time. You may need to run vacuum for a few hours depending upon how much moisture is in the system and the quality of your equipment. On my own vehicles, I run an overnight vacuum.

Dougflas wrote:This is exactly the reason I state a 30 minute vacuum is useless. As suggested, keep the vacuum going for a longer period of time. You may need to run vacuum for a few hours depending upon how much moisture is in the system and the quality of your equipment. On my own vehicles, I run an overnight vacuum.

If you vacuum for a second time 30 minutes later. It normally will stay at the lowest vacuum.