rejuvenating A/C system

[gramps77]

need to replace my old compressor that is original to the truck and R-12. What else should I replace or have done while doing so?

[Just call me Sean]

Expansion valve/orifice tube, accumulator/dryer.

[Skunksmash]

I'd take it to someplace that will do it for a reasonable price and give you a warranty. New systems often leak and have to go back a few times before they're perfect. I paid $320 for everything when I had to redo mine. That's parts and installation. I got a 2 year warranty and it has gone back a few times when all the freon leaked out. And if it leaks, don't run the compressor or you'll kill it. Found that out the hard way. You'll notice the air not blowing as cold, or fading from cool to cold. That's when you stop using it and take it in for warranty work.

[hatzie]

What year is it?
Are you planning to refill with R12?
The 73-?? systems used a TXV rather than an orifice tube and are less tolerant of differing refrigerants.
If you have something that looks similar to this then you have the early TXV AC system.

The later Orifice valve systems are more adaptable and are a fairly easy to retrofit.

[hatzie]

Originally Posted by Skunksmash

I'd take it to someplace that will do it for a reasonable price and give you a warranty. New systems often leak and have to go back a few times before they're perfect. I paid $320 for everything when I had to redo mine. That's parts and installation. I got a 2 year warranty and it has gone back a few times when all the freon leaked out. And if it leaks, don't run the compressor or you'll kill it. Found that out the hard way. You'll notice the air not blowing as cold, or fading from cool to cold. That's when you stop using it and take it in for warranty work.

Sounds like your Low Pressure Cut Off Switch is stuck or bypassed. The compressor shouldn't turn on at all if the pressure drops.

[gramps77]

Originally Posted by hatzie

What year is it?
Are you planning to refill with R12?
The 73-?? systems used a TXV rather than an orifice tube and are less tolerant of differing refrigerants.
If you have something that looks similar to this then you have the early TXV AC system.

The later Orifice valve systems are more adaptable and are a fairly easy to retrofit.

Its a 77 and I totally forgot to check yesterday for that. It should be on the firewall box correct? Just at the bottom?

[hatzie]

Originally Posted by gramps77

Its a 77 and I totally forgot to check yesterday for that. It should be on the firewall box correct? Just at the bottom?

It'll be on the firewall box. I've forgotten whether it's on top or bottom.
I Converted mine to the 80's orifice tube setup for Hydrocarbon refrigerant. But that's not for everyone... R134 will work OK at cruising speed with the right components.