sealing an AC system.what the heck?!

[dmartin1]

so im putting the AC system back together on my 1978 k20.

everything cleaned out,and im putting lines on it etc..but i want it to be completely sealed so i dont waste money on freon.

i bought the complete o ring seal kit from napa..

theres like 30 o rings in there?!

does anybody have a diagram on where all of these go?

i need helpp.first time doing an AC unit.

[gmachinz]

No, you don't need all those o-rings. Everywhere you have a fitting, you have an o-ring. Just collect your original o-rings and take them to the parts store and match up sizes with the 2-pack kits or smaller o-ring kits so you have all the correct sizes. You want to change out the orifice tube and drier as well. If this is yoru first AC overhaul, do you have a vacuum pump? You need one to pull the system down to verify you have no leaks first. PM me if you have questions-I can walk you through the steps. Trust me, no parts store will have a vehicle specific o-ring kit for any given vehicle-further, no parts store catalog system is good enough to find what you need. You just gotta match up what you have to get the right ones.

[dmartin1]

whats the drier and orifice tube?

how come i gotta replace them?

[gmachinz]

O-rings dry out and crack/shrink with age so they will eventually fail to seal. The drier is that cannister looking thing coming out of your ac avap box on the firewall. There is a high pressure AC liquid line down low coming out of the evap box-you will see a fitting there-open it up and there is an orifice tube inside that aluminum that I guarantee is cruddy....you need to replace that piece. If you have never worked on an AC system b4, I suggest just reading up on the basics.
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[Slonaker]

I'm not an expert, but I have been through this a couple of times...

The drier has to be replaced any time you open up the system. It is filled with dessicant to absorb moisture that will cause damage . When you open everything up, the dessicant absorbs all the moisture it can, so it has to be replaced.

The orifice tube costs only a few dollars, and should be replaced as well. It tends to catch debris that might be floating in the system. If it is full of crud, as gmachinz mentioned it could be, you should flush the system before going any further. It means that the system has had a major problem at some point in the past. That crud will be floating in there after you put it back together, and it will likely cause damage.

It sounds like a lot of expense and trouble, but skipping these steps will likely screw it up and force you to start all over again. You might as well do it right the first time.

Slonaker

[gmachinz]

Right...the orifice tube will likely have small pieces of metal from normal compressor wear as well as ac oil that has broken down. You should pull the lines and condensor with an ac flush....then blow out with compressed air....then assemble everything with new orings and pull it into a vacuum. Let it get down to and hold 29-30 inches of vacuum 4 at least an hour....then u should be good to go with the charge.
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[grs]

Did you change over to R134a? Just make sure you put the correct oil on the O-Rings before you install then. You will have to put oil in the system also. Go to an AC shop and get there advise.