I have a 1967 F-100 with an after-market, in-cab, air conditioner by AIRefrigeration. I need to convert it from RA-12 to RA-134. How would one purge the old gas and oil, and how many ounces of the new freon should I put in?

 

Check with your favorite parts house, I believe there are kits out for doing that.

The newer compressors are easier to turn than the older ones, converting to one of them may be easier on the mpgs.

John

 

Whoa there, watch those parts house conversion kits...they're commonly known as "Death Kits" among the A/C service community. They have a sealer/stop leak in them that can clog the system up, and they don't allow for getting the old oil out of the system. They can work fine for a while, and then it all goes to crap when your orifice plugs up and the compressor isn't getting properly lubed.

The best way to do it is to first have the R12 evacuated by a shop with a recovery unit (if there's any left in the system) and then you have to open the system, remove the compressor and turn it upside down to physically drain it of the old oil. (The oil used with R12 is incompatible with R134A). You should also flush the system and get the old oil out of the evaporator and condensor, and you need to replace the filter-drier canister. It's not a bad idea to replace the orifice tube with an R134A tube, but I've heard of people having good results still using an R12 orifice.
You'll also need to replace all o-rings in the system with HNBR rubber o-rings to help seal against the R134A.

You'll need to draw a deep vacuum on the system when it's buttoned back up and charge with the appropriate amount of refrigerant (can't say for sure what that is...sorry)

It's a little more involved than that, and I'm no A/C tech but I've done a few systems and read up on it quite a bit. I'd go haunt the A'C forum a bit, I'm sure you'll find a few threads there about doing conversions as well as get some good info from more qualified A/C techs. My main point was to stay away from the death kits and don't ever put stop leak in your system.

 

Sorry Dan, I was not aware of those dastardly death kits. That is not the one that I was suggesting.

John

 

Maybe you've got smarter parts people back there than we have here on the Left Coast, John... Here, you walk into a parts store and ask for a retrofit or conversion kit and a death kit is what they'll happily sell you. It's actually tough to get anything else...that's why I buy my stuff online.

My first time doing an R12 to R134A conversion, I did everything wrong. It was on my mom's Taurus, the compressor had died so I bought one at a wrecking yard and swapped it in, then added the death kit. Didn't replace the filter-drier, didn't add the correct amount of oil to the compressor (the refrigerant in the kit I bought had oil in it so I figured I was good to go) and I didn't pull a vacuum on the system. When I got it charged up, it blew 36º through the vents on high, so I was happy. Then, the next summer...nothing. The stop leak reacted with the water that was in the system from not replacing the drier or pulling a vacuum and plgged everything up. The system was junk after that. It was about that time that I learned about death kits from reading A/C forums and realized that I had some first-hand experience with them...

 

Gosh, I hope the kit purchaser didn't add to the meley.

John

 

Those conversion kits work great. Originally the R-13 wasn't compatible with the R-12 oil, but that was waaaaay back in the R-13's infantancy, but it's fine now. Read the instructions. No need to change the dryer, seals, etc. I converted my '84 using a Wal Mart kit, the system had no R-12 in it when I bought the truck. All I did was screw on the adapters, put the new oil and R-13 in and it worked great for the next seven years, right up until I sold the truck.

 

Mineral based oil used on R12 is not compatiable with 134A. If you have more than 5% mineral based oil left in the system, the new conversion dryer can not handle it. It will run for a year or so before the acid eats the whole system up. Then you have to replace every thing that is made of Alum.

The only correct way is drain all the oil and flush lines, cond, evap. Then put the new oil that is compatable with 134A, there are several that will work. With the conversion you will loose approx 25% of your capacity. 134A requires a larger cond and evap to get the same efficiency. But these small cabs do not present any problems.

I have enough R12 to keep my 68 F100 orig.

 

I bow to the pros

 

Orifice tube? Don't these come with an actual expansion valve?

As an HVAC tech for the past 20 years, I would contact a local HVAC company and have them help you. The risk of you damaging something or hurting yourself isn't really worth it in my opinion.

 

And learning is out of the question??

 

Sure… in Sweden it’s a 2 year vocational university, plus a certification test. The chemicals (refrigerants and oils) are dangerous both for you and the environment… the pressure and temperature that the system operates at are harmful. Be careful, you risk serious injury and/or damage to your vehicle.

I occasionally help people out with their a/c conversions, and it doesn’t have to cost an arm and a leg… you might ask someone to show you what to do.

 

Can you take a few pictures of your system so we can see what you are working with as it can help us help you.

Also when was this system last working, is it sealed or parts missing and open to the air?
Dave ----

 

How are your vents installed if after market A/C unit ? I want to install A?C in my & wonder how to install vents ?
Oh I just remembered the unit has the vents in it , duh.........Anyway if you can add anything I apologize for the interruption
Good luck , appears you & I am getting good advice here.......ha................

 

Thanks anyway.