Ac
The small AC line by the accumulator is the high (pressure) line. It goes into the evaporator core. The orifice tube is installed in line at the connector (3/4" and 5/8" line nuts) spot. The proper way to diagnose your car is with a set of AC gauges, so you can see both high and low pressures and their relationship with each other. It's possible a low freon condition (from a small leak) could cause that spot to freeze up, along with no cooling. More likely is trash from compressor wear has clogged up your orifice tube and made for a restriction, as you surmised. Orifice tubes are cheap, but replace the accumulator /drier, also. Gauge readings on a correctly filled system would be 225 high/30 low, depending on ambient (outside) tempature. A restricted system would show readings like 300-350 high/5-15 low. If when you first hook up the gauges (engine off), you get static pressure of around 40 psi (assuming it's not 19 degrees outside), then you're low on freon. If it's low on freon, you have a leak. Please, do not use any stop leak product. Find and fix the leak. I'd recommend a professional to diagnose it for you, money well spent. Then you can decide if you want to replace the parts and have him evacuate/recharge it for you. HTH.
