Automotive Air Conditioning Information Forum

When using a micron gauge, where do you connect it to the system? If a system is sealed up good, how low should the micron level go when vacuuming?

Thanks,

Tee it into your vacuum pump- anything below 500 microns is excellent--but it all depends on your vacuum pump's ability to pull a good vacuum- you can always deadhead the micron gauge directly into the vacuum pump to test the pump only- and its ability to pull a good vacuum- some vacuum pumps are worn out....you can also see if system holds vacuum by isolating the system from the pump (shutting off vacuum pump valve) and see if micron gauge rises- which would indicate a leak in your system.

I changed a hose on a car yesterday and it was my first opportunity to vacuum with a micron gauge. It got down to 270 microns. My trouble was coming up wth a way to isolate the system and gauge. I'm thinking I need a tee with two metric male connections and one SAE?

My pump is an older one, but still gets to 25 microns.