95 Ac stops working after 20 mins driving

[Chickenman]

Can anybody help. I took the car to the dealer and the system was evacuated and then recharged. It blow ice cold but after 20 Min's highway driving it just blow cool air. I checked the relays they are working. Any thoughts? Thanks

 

[Justinlhc]

Sounds like it might be a bit low or one of the pressure switches is bad. I'd take it back to the shop that charged it and have them fix it.