Ok guys I rented a vacuum pump, got it hooked up, and vacuumed the system. Now heres the problem because i get contradicting answers to the question. Once it has been vacuumed, the low side manifold gauge reads 30 psi and the high side reads 0 psi. Is that correct? Now I let is sit to see if it holds vacuum and the low side goes from 30 psi to 10 psi. It doesnt makes sense to me that it appears i have a leak but it wont hit zero psi. can someone help me out?? thank you.

 

Make sure that your low and high side valves are open on the gauge set. With both valves open, it should vacuum down. When your done, turn off the vacuum pump and close both valves on the gauge set. It should hold vacuum as long as there isnt any leaks.