(strange?) problem with AC in 960

[ginnyneko]

Hello everyone! I am having a problem with the AC on my 960 Volvo. I thought it just needed to be charged, so I checked the freon pressure and it was at 45 psi. Soooo, I checked the pipes leading from the AC and neither were changing temp; I expected the top to get hot and the bottom to cool and condensate, but they didn't change temp at all. I pulled the idle cable on the engine to see if it would drop the psi, which it didn't. My dad is a mechanic, and he was giving me instructions, but this had him stumped. Any ideas? Thank you in advance for your help! If I used incorrect terminology, I apologize; I'm a complete novice, so thank you for your understanding

[ginnyneko]

so a friend thinks it may be the expansion valve, does this sound right?