[Goofee691]

I bought a vacuum gauge for my 91 volvo 240 and installed it, first I hooked it up where the climate controls get a vacuum from but the guage would read 15psi at all times, I think its because of a check valve I had read about online which uses a different size hole than the tube for the guage or climate controls and drops to the size needed for the climate.

I found another vacuum hose hookup that I teed off of but I would only read a little under 5psi which would drop as a accelerated and return to 5 after I took my foot off the gas. Is it normal for one area to only have 5psi?

I noticed some nuts in the manifold that I'm guessing could be used with a compression fitting if I were to buy one. would this be the best option to get a proper reading on the gauge?