AC help on an r12 rig

[crawlin40]

Okay guys, I know nothing about ac other than my son’s earyl 93 (12/92 build date) does not blow cold and Fort Bragg is hot. I currently have the truck up here in Reading PA to get this resolved. My friend who is a truck mechanic and Ford guy knows ac. This is what we have. System has about 22oz of r12 in it. Sticker say 30oz needed. So I am short. That’s all I currently have. I am willing to buy one more can on fbmp if needed. After the first can, no more bubbles in the glass. Put the second can in. No visible leaks. Below are the

numbers with the motor turned off for 25 minutes. He thinks a clogged drier. That’s an inexpensive part and he has a functioning r12 machine to recapture the r12. Any ideas are greatly appreciated.
Thanks.

 

[Pacer]

New OEM receiver dryer is the ticket, I don't know if it's clogged, but there's a desiccant material in there that absorbs moisture. When the system has been discharged/open for a long time, it becomes saturated and should be replaced.

Once the system is evacuated, I often take the opportunity to blow brake clean and compressed air through each of the components in the system.

At this point, with a new R/D you have the opportunity to convert to r134 if you like.

Pull vacuum, let it sit for a few hours to leak check.

With r134, charge to 80% of spec for r12.

 

[crawlin40]

Ok. Thanks. What about the expansion valve? Could that be a possibility too?