Need help diagnosing ac problem

Friendly format provided to inquire about automotive a/c systems.
Archived Forum

Moderators: bohica2xo, Tim, JohnHere

User avatar
JohnHere
Preferred Member
Posts: 1192
Read the full article
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate - USA

Re: Need help diagnosing ac problem

Post by JohnHere »

Dbwy wrote: Fri Nov 26, 2021 9:08 pm Ok so the Freon can was freezing up and it took like 30 minutes to get the car to take Freon. You guys were right, it’s working great now! Thank you so much for the help!
Dbwy wrote: Fri Nov 26, 2021 6:45 pm Maybe I didn’t vacuum it long enough? But after the vacuum both gauges were at 0.
Glad it's working now. But will it remain working over time? Probably not because the system has a leak, which is indicated--at least in part--by the vacuum leaking down to zero on both gauges right after you evacuated it. Presuming your gauges don't leak, a tight system should hold vacuum indefinitely. If the vacuum leaks down like that, air and moisture will also be drawn into the system through the leakage point(s), contaminating the system. You need to find that leak.

Speaking of evacuation, a good vacuum on an A/C system should register about 29.9 In.Hg. (Inches of Mercury) at sea level on your low-pressure gauge and be maintained for at least 30 minutes to effectively remove all air and moisture in the system. A reading of only 10 In.Hg. for 15 minutes is woefully inadequate. I would also replace the desiccant before evacuating the system.

An air-powered vacuum pump, if that's what you're using, isn't capable of pulling a deep enough vacuum.
Member – MACS (Mobile Air Climate Systems Association)

Thankful for the responses you have received? Please consider making a monetary donation to the Forum.
Post Reply