Re-installing AC

[CA Big Red]

Living up here near Sacramento, CA, I want to get AC back into my pickup before this next summer. I picked up a compressor and all the hoses of a donor rig that was working prior to being parted out.

So, I'm looking for good info on how I can piece my system back together. Any good threads on this being done?

My compressor was taken out in 1995, leaving everything else. However, I know there issues with the system being "open" and contamination issues. So, are there ways to test the system?

I'd appreciate any direction or ideas on next steps to ensure success. I've got time now, but summer will be here before I know it.

Thanks in advance.

[LTZ C20]

You will just have to start flushing everything and cleaning it all up and putting it together with new seals.

Flush the condenser, lots of brake clean and compressed air works good. Flush all the lines the same way. Probably best to get a new accumulator,  unless the one you plan on using you know for sure is good. Flush the  evaporater the same way also. Then start putting it all together,  new seals and O - rings at every location needed, new service ports also, now would be a good time to convert it to R134 if that hasnt been done yet. Use a battery to give power and ground to the compressor and see that the clutch engages and disengaged properly.

Once you have it all clean, connected and ready to go, do this yourself if you can or take it to a shop and have them vacuum down the system to ensure it holds vacuum. If it does, charge it up with the proper amount of PAG oil and refrigerant and test it out.

[roundhouse]

The stock condensor in front of the radiator Is kinda small for 134

I've seen several people use condensor from a 90s Yukon or Burb
The 134 needs a larger condensor to shed the heat


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[CA Big Red]

LTZ C20, you're suggesting flushing the condenser with shop (compressor) air the different parts using lots of brake clean. Can I do that with the whole system?

I guess I have the choice between 134 and R12. I've been told 12 blows colder, is that true?

Roundhouse, I assume they have a fabrication for the brackets needed to mount the 90's style condensor?

[LTZ C20]

Yes, spray lots of brake clean in one side and then air thru the same side and watch all the icky stuff blow out the other side. Then use brake clean and air to blow thru the hoses, just don't run it thru the compressor.

You can use are 12 if you can find it, but it's been outlawed so good luck, 134 is what we got now. I wouldn't worry too much about the condenser size, I have my stock condenser and 134 and the system blows very cold.

If you have a 90 ' s compressor, you will need a serpentine bracket system for the whole front of the engine,  for power steering and crank shaft, basically it would be easier to just get the right compressor for your year. I did a serpentine swap on my engine, but with the brackets and powder coating them I wanted, new alternator and power steering and all the pulleys and belt and all other needed parts I have almost 1,000 dollars into just that swap. I also had to get custom hoses fitted and made to adapt the 90s style compressor lines to the older style truck lines.

[roundhouse]

I was suggesting using 12 if your system has 12 in it and is still sealed up and just needs topped off with a little more 12 to get it working colder

If its open go back with 134


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[CA Big Red]

Thanks guys. Roundhouse, you suggested a condensor from a 90's Yukon or Suburban. I was curious about how it bolted up to the 78 I've got. Any idea? I could be on the look out for the larger condensor, but I assume it will need to be fabricated to fit? 

[Jason S]

This may be a bit late, but maybe this will help a little...

I picked up a compressor and all the hoses of a donor rig that was working prior to being parted out.

Compressor- What compressor did you get?  If it's the long A-6, they are generally good compressors - but rob some power. Whatever it is- just make sure to try to check it out as best you can. Apply power to the compressor clutch to make sure it engages. Turn the compressor by hand and listen for any abnormal sounds and 'feel' for internal, mechanical issues.  Drain out the oil into a container- look for particles, metal flakes, etc.  Refill compressor with appropriate amount of new, clean oil correct for the chosen refrigerant. Replace O-rings at back of compressor with new, oiled O-rings.

Hoses- If they're used hoses, check over the hoses thoroughly and look for any deformities or other issues in the rubber (or plastic) hose and the metal fittings. Looking them over, if you feel they may have a compromise, then replace them. I've lost over $100 of R-12 from a bad $10 hose... Replace O-rings at all fittings with new, oiled O-rings.

Evaporator-As long as the inlet and outlet lines haven't been kinked over, as I've often seen on an open system, then you can probably just clean/flush it out.  If it's been open for 20 years, make sure it's thoroughly flushed out- small critters and insects can often times make their home in the strangest locations.  If you can remove the evaporator from the truck, then you could clean out the plenum box and the evaporator fins as well as making it a little easier to flush out.

Condenser- for R-134A, if you go with a little larger condenser it would help- however, you may run into adapting fittings and making brackets. On both of my trucks they have 134A; I've run the factory style condensers and they work well too.  Only issue that I've had is during one scorching summer with 115 to 120 degree temperatures...

Orifice tube- Replace

Accumulator (drier)- Replace. The desiccant inside removes any moisture from within the system. The desiccant can be saturated, also the desiccant or the sock that holds it can deteriorate.

Oil- use the oil appropriate for the refrigerant. PAG or Ester oil are two commonly used oils for R-134. 

When I rebuilt the A/C system in my '74, some of the parts were  used (e.g., condenser). I took the used parts to an A/C shop to have them flush it- I don't recall the price, but I don't think it was too much since I was a poor college student. I figured they'd have the right solvents and equipment to do a thorough cleaning.  I tried to make sure everything was as clean as possible before assembly.  It's been good for over 15 years now.   

On my '73, back in 2004, I replaced an aftermarket A/C system that I had installed with a factory A/C system. The condenser, evaporator and hoses were new.  The compressor was rebuilt. Again, I tried to ensure everything was completely clean and it's been good now for over 10 years.

So, I'm looking for good info on how I can piece my system back together. Any good threads on this being done?

I'm not aware of any threads.  If you're using factory parts then you should be able to follow the Factory Shop Manual for your model year truck. There should be a pdf of the factory manual in the tech section on this site. Also, I (or others) can post some photos of a factory setup if there is something specific.

I know there issues with the system being "open" and contamination issues. So, are there ways to test the system?

Once everything is cleaned up and flushed out, and the parts are all connected (i.e., A/C system is assembled), then you can attach a vacuum pump and gauges to the system (Autozone rents them) and evacuate all the air. It'll take around an hour for the system to be evacuated.  After the system is evacuated, shut gauge valves, leave the gauges connected and turn off pump. Then after at least an hour, check the gauges to see if any vacuum has been lost.  If so, then there is a leak somewhere- often times it's a fitting but it could be a compressor seal, evaporator or condenser.

If you're satisfied that the system is evacuated and holding vacuum, then charge with your choice of refrigerant. 

I guess I have the choice between 134 and R12. I've been told 12 blows colder, is that true?

  In my opinion, R-12 works better in the 70's and 80's trucks than R-134a; however, R-134a still works well. Considering the current availability and the price difference of R-12 vs. R-134a (unless you score some R-12 cans cheap), it's usual to just switch to R-134a.  Watching for sales at autoparts stores and some of the farm supply stores, I've picked up R-134 for anywhere from $6-$8 per can.

[LTZ C20]

Jason S has covered everything I said in the beginning, only he has done it with greater detail and extra specifics. As long as you follow our examples and the shop manual, you shouldn't  have a problem getting your A/C back!

Well done Jason.

[78BIG-TEN]

X2 Jason

[CA Big Red]

Jason S, if there wasn't a good thread on this before, I think you nailed it. This should get a novice like me through.

I'll keep you posted and let you know when I'm done.

[Jason S]

Jason S, if there wasn't a good thread on this before, I think you nailed it. This should get a novice like me through.

I'll keep you posted and let you know when I'm done.

Well, I sure hope it helps.  Take lots of photos!

[LTZ C20]

Yes we would love to hear your progress and see pics of how it's going.

[CA Big Red]

So, I bit the bullet. Purchased a VintageAir system. This after I collected everything I needed for the stock system install.  I decided to go Vintage for the guarantee, the technology and a buddy of mine who just put one in and swore by it.

So, I hate to disappoint, but I am going the other direction and will post pics along the way a, but will start a new thread for that.

The project summits underway, but I've been waylaid by the amount of rust I found in the floors.

[CA Big Red]

New floors! Let the vintage air install continue!