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73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: dvdswan on February 24, 2014, 11:04:46 am
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Ok, so I located a local j/y that has a 78 crew cab with factory AC and I can get everything in the interior (vents, ducting - heat and ac, controls, cables, and etc) plus the stuff on the outside of the firewall for $50.
my question is - is all this compatible with newer stuff like the 134a freon? or should I not worry about that and just use R12 (if its still available). when it comes to installing the freon I plan on taking it to the local garage to have them evac and fill.
I know I still need to find a condenser, compressor and hard lines.
should I grab any connectors, brackets, or other parts in particular? there is no engine so I cant get the engine brackets but I'm sure I can find them sooner or later.
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If you are getting all this for $50.00, I would grab everything nuts, bolts, brackets, everything you have to take off to get the parts I would grab.
I am not a AC expert, but I believe I read somewhere that not all systems are compatible between R12 and 134A, but if my memory serves me right, I believe you might have to change some o-rings for the new R12.
Someone who knows for sure will chime in and say for sure.
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I think R12 was used in the 70s and early 80s then was changed to R134a for better cooling or less damaging to the ozone something like that.
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I don't know about better cooling, but I do know that R12 was phased out because of damage to the ozone. I think you'd be fine going to R134. Just get o'rings and such meant for it. R134 seems to go warm when idling. The way to fix this is to put an auxiliary electric fan on the condensor. My son's '90 454SS was converted to R134 and had an auxiliary fan, it got frosty
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So I pull all the junk I could get, right down to the vacuum tanks and kick panels. Question though... are all the AC controls vacuum operated and just heat temp on the cable or is this something different from the rest?
maybe I'm going off what my Nissan truck is because it has cables for everything.
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I believe on the 78 there should be both cable and vacuum controlled parts for the AC.
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This is correct. The cable adjusts the hot/cold blend door. The vacuum adjusts the diaphragms that go to defrost, feet, face, vent.
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Cool, thanks for the answers.
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You can run 134a and any of our trucks...
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There is a standard process for converting from R12 to R134 and its been done on many vehicles. In most cases you use a smaller orifice (very cheap part), different oil that will mix effectively with R134, a new filter/drier that is rated for R134 (very easy to find), and new charge fittings for R134 (you can adapt the R12 fittings) and then charge the R134 to about 75% of the recommended amount of R12.
You will need to find an AC shop that will recharge with the amount of R134 you specify. Some shops are so used to newer cars that if they can't find your vehicle in their lookup table they can't figure out what to do. R134 systems are much more sensitive than R12 systems to having the right amount of refrigerant, so you want the shop to use a very specific amount. A few ounces too much or too little can affect cooling quite a bit.
Some cars that are converted have issues with the condenser (mounted in front of the radiator) being too small to be effective with R134, but the cab on these trucks is so small that there should not be a problem. There is also the possibility that you will need to replace the current rubber hoses with barrier hoses that can contain R134a better (it has smaller molecules than R12). However, stock hoses in good shape may also work fine.
Bruce
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Some things to read here: (really need to compile this and make a topic on it) If you need more, copy/paste this straight into google R134A site:73-87chevytrucks.com
http://forum.73-87chevytrucks.com/smforum/index.php?topic=8386.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=8593.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=21133.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=24125.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=12561.0