In looking to get my 84's AC operational again, I've been doing some research on the interchangeability of the front compartment lines between the different years. I ruined the original lines on my car when I attempted to seperate the condenser from the lines, because they had corroded together, so I bought another set through The Mall here for an 84, and a set from an 87 from a local junk yard.
On the 84 Fiero, there are two hard lines in the front compartment: a short one, and a long one. On 85+ cars, there are a short one, a long one, and a REALLY short one that connects to the end of the long one, that also contains the orifice tube. On the 84, the orifice tube is in the inlet to the evaporator, and requires a special tool to remove. On the 85+ cars, the orifice tube is right at the end of the really short line, and can be pulled out with needlenose pliers.
The short lines are IDENTICAL between 84 and 85+ cars. Exact same line sizes and o-ring sizes.
The longer lines: Good news for 84 owners, is the long line and the really short line from an 85+ car are interchageable with the 84's long line. This also means you can now have the high side fitting in the front compartment, instead of using really long lines with you manifold gauge set, and stretching between the front compartment and the engine bay. 85+ cars cannot use the long 84 line, because then they wouldn't have a high side fitting.
The high side fittings are the same size on the 84 hoses and the 85+ long line.
If you're keeping the system R-12, the high-side schrader valve should be replaced, GM part # 10027604, AC Delco part # 15-5375. If converting to R-134A, it should be removed and replaced with a high-side fitting that has it's own schrader valve, like 4 Seasons part # 59978
Also: why it's important to seal you AC lines when the system isn't connected:
This short line came from an 84 pace car, that had apparently been left open to the elements for a while. Both ends of the line had this weird white buildup at the ends:
Chipping it out, I found the line was filled with dead bugs that had probably been living there for a while. Applying air pressure to one end of the line wouldn't blow it out. I think I'll try soaking the line with carb cleaner and trying again later, but I probably won't be trying to use this line on the car.
