AC Won't cool

What is the tev? My high side is maxed out

 

This^^^^^

 

There’s your answer. If you’re sure you only have 3 cans in it now. I was going to suggest adding 1 more can. 3.88 lbs= 62 oz. = 5.17 12 oz. cans. Looks like your over 2 cans low. Adding 2 cans, along with 1 - 3 oz. can of oil with green dye, might just be the ticket. The dye comes in real handy when there’s a small leak. My Classic takes 55 oz. I usually put 5 cans in. Bleeding a bit first from each can, to eliminate air in the line. Works out good, gives me a bit extra, less than 10%, not enough to hurt anything. As I recall my 92 WS took a bit more. Make sure the temp sensors working. You can hear it click, when it turns the compressor on. Also make sure the clutch is cycling on and off properly while at a high idle, it should shut off from high pressure, even though fans engaged. Should be engaged longer than not on the hottest most humid day. Preferably engaged twice as long as not. That Truck has a trianary switch. Fans welded, so can’t check the operation. Still if adding 2 cans causes problems. Might have a bad trianary switch, causing it to cycle the clutch off, other reason would be a blockage probably in one of the expansion valves. I’d also turn the water valves off, if open. Pretty sure you have air over electric thermostat type control valves on the cab and bunk. You can tell, if it has an air line running to them. Cab
valves usually on the firewall, follow the heater hoses. Bunk valves under their bunk. When either one goes bad, once coolant temp is reached in cab or sleeper, or when the keys turned off, and powers cut off, they put 100 psi into the coolant. Symptoms look like a blown head gasket. Don’t fall for that one. Turn water valves off, if that ever happens before assuming the head gaskets blown.

 

Thermal Expansion Valve. If your truck is old enough, it will have an orifice tube instead.

 

Yeah, it’s low. Might keep cool on mild days. Won’t keep up on hot days. You need to add a couple 12oz cans. Add them upright, in vapor, might take a while. The Running it low will make the compressor run hot, and shorten the life of Compressor and clutch.

 

If you're going to charge based on pressures then use this chart as a guide...