AC gauges look ok?

[Shawn]

First time using this type of gauge set. Have always wanted to get a decent set but nothing justified getting a set until now with the 91 Blazer's aftermarket Frostemp AC made by Wynns back in the 90s. After pulling a good vacuum an hour, I loaded three 12oz cans but left the last can with a little left so maybe 28-30oz total. The Vintage AC systems are known to take 28 oz and it appears mine is similar in size. It was 70 degrees outside so it looks like I'm good going off this chart. The system is blowing cold but don't have a temp gauge to measure temp. With the AC compressor cycling, do these gauges look to be in normal ranges? I'm pretty stoked to get this AC up and running after sitting for over 15 years and the system was missing hoses, missing condenser, and had a bad compressor.

 

[Blue85]

The low side is really low. Below 28psi R134 is below the freezing point of water. As the compressor turns off, the low side instantly jumps up, as though there is no liquid still boiling off. The high side is also kind of low, but might be reasonable if you have big fans. Is the evap inlet cold and outlet warm? With no more information it sounds undercharged.

 

[Chickntrk]

I agree, undercharged

 

[Shawn]

The low side is really low. Below 28psi R134 is below the freezing point of water. As the compressor turns off, the low side instantly jumps up, as though there is no liquid still boiling off. The high side is also kind of low, but might be reasonable if you have big fans. Is the evap inlet cold and outlet warm? With no more information it sounds undercharged.

Thanks! Maybe I'll throw another can at it. I wish I knew just how many ounces this system takes. Its a bone stock 91 Blazer 350 TBI with the stock clutch fan with a new crossflow condenser made for R134. The aftermarket AC system looks like it came with R134 due to the fittings.

I'm just happy I can finally drive this thing on a hot day without getting my back soaked!