clm65

I just finished replacing the evaporator core in my 2010 F150, and bought a set of Harbor Freight manifold gauges and vacuum pump to evacuate and charge the system. The pump pulled the system down to 30 " hg fine, but when I went to see if the system held pressure by isolating the pump, I lost vacuum fairly quick (over a few minutes). I tried running the pump for over an hour, and same results. At first I thought I may have a leak in my AC system. But then I isolated the gauges at the connection to the truck's high and low pressure ports. I waited a half hour and opened the valves up, and I was still at 30" hg. Closed the valves and waited another 1/2 hour and still holding. So I'm pretty confident the system is sound and the problem is in the manifold. So I run out to Harbor Freight and exchange the gauge set. Try new set - same thing, but a little better. This time I figured I would try to add the refrigerant anyway. The low pressure hose seemed to be leaking at the ferrule the whole time, and the o-ring between the quick disconnect fitting and the hose blew out on the high pressure side half way through. I ended up using three 12 oz cans of 134a (36 oz), even though the system only takes 24 oz. And I apparently didn't get enough in there, as the air only blows at about 59F.

So, are there any tips to get these gauges to stop leaking?

And what is my next best step? I don't know how many ounces are in the system right now. Can I charge it based solely on indicated high or low pressure? If so, what pressure should I be shooting for?