Puzzling issue with an 04 Exp with manual AC. Front AC suddenly started blowing hot air. Rear AC still blows cold. Replaced front blend door actuator but no change. Gage on AC recharge bottle showed level was low so I added a can. Front AC still blowing hot. Noticed ice build up on low side line but only from the front of the truck until the low side port. No ice from low side port towards the firewall. Any advice before a shop wants to charge me more than the truck is worth?