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I have an older truck (93) and need to replenish my dying r12 AC, but was thinking of doing the upgrade to R134. I've seen the kit at Walmart, but also have heard that you need A L L of the R12 out before you add the new R134 because it will screw things up.
Is there a simple way to do this? All i want to do is upgrade my system to R34a......but do it the right way. Hopefully i dont need to pay someone to drain my old system in order to upgrade to the new. If you know how to do this, please tell me how.
You will need someone to recover your R12; purging to the atmosphere, especially with R12, is verboten. After that, you'll need a new accumulator, orifice tube and conversion fittings at the minimum. You'll also need PAG oil; ester mineral oil, as used in R12 systems, doesn't play nice with 134a. 2-3 ounces in the new accumulator (if it doesn't already come with oil, some do, some don't) will do.
You'll need to flush the condenser and evaporator out; you can find flushing solution at an A/C supply store or maybe an auto parts store. Add flushing solution to the condenser and evaporator, blow through with compressed air. Repeat two or three times. Afterwards, you'll need to vacuum the system down. I'd recommend at least an hour, pull it down to 30" hg. Then let it sit afterwards for about ten minutes to ensure that the system is intact and showing no leaks on the vacuum end.
Charge the system with 134a. R134a operates at higher pressures than R12 does, so you'll need less refrigerant, approximately 70-80% of the R12 charge amount. Now, here comes the catch: The higher pressures may make leaks that were small or insignificant with your R12 hoses and lines serious with R134a. Additionally, the condenser may not be efficent enough to operate with 134a. You'll just have to try it and see. At one time in my neck of the woods, you could get a "complete" R134a conversion kit, which included an accumulator, orifice, a bigger condenser, discharge, suction, and liquid lines, oil and flush. Might want to try checking around some A/C shops in your area to see if they offer a similar package.
To recap, at the bare minimum, you'll need to have your R12 recovered; you need a new accumulator, orifice tube, service ports, and PAG oil. You may need new line(s) and/or a bigger condenser.
I bought my son a 90 F-150 and the air conditioner was low on R-12. I bought Freeze 12 to add to it. It works in R-12 systems but does not damage the ozone. It's as easy as adding R-12.
Be advised that additives will not make you a popular guy the day someone hooks their charging station to your truck to recover the refrigerant. The way this stuff is marketed, it looks like a complete replacement for R12, not necessarily an additive, even though it'll function in that aspect. Not an issue if you've got a shop that has the equipment and deals in this stuff. I Google'd Freeze 12 and found...
What are the requirements for recovery equipment with Freeze 12?
The EPA requires that recovery of Freeze 12 must be done with a dedicated recovery unit. TCC offers a competitively priced unit for this purpose.
So, it'll contaminate a (very) expensive cylinder of R12 should someone use their R12 charging station to recover the refrigerant out of your system. If they use an identifier prior to hookup and see that you've got something else other than 100% R12 and some air or moisture in there, chances are they won't touch it with a 10 foot pole, leaving you SOL. Probably not an issue if no one else ever looks at it, but still.
I did a complete conversion of my system on a 1992 Flareside. Since the compressor already died the black death and the evaporator sprung a leak, I didn't have to worry about recovery. I replaced the compressor and filled it with the proper oil. Replaced the Filter/Dryer, and evaporator. I went online and found a 'smart vov' which is a variable orifice valve. It costs about $20 and I would not do a conversion without it. Anyway purged the rest of the lines with denatured alcohol and replaced all seals. Put the system together, pulled vacuum and added 134a. This truck cools better now than it did with R12 while moving, however expect some loss of cooling while sitting still. The condenser (hope I have it right. Usually get them backwards) is not quite large enough for a 134 system but will work. That is where the smart vov comes in handy. I did the research and it wasn't that hard, plus saved a bunch of money on parts and labor
Would have loved to use Motorcraft parts, but it would have put me way over budget on this job. Using a GPD kit, I was able to do the whole job for ~$400 including dye, and r134a.
Everything was bolt on, with two exceptions:
the '95 R134a evaporator was not a direct fit for the '92s airbox. Nothing a dremel and some black silicon caulk couldn't fix.
Modified airbox. Filled in the gaps with black silicone caulk. Worked out great.
The only other issue was the low pressure switch. Simply swapped it out with an R134a version because the threading on the valve is different than the R12 version.
Purged the system for 30 minutes and pulled a 30in. Hg vacuum for 45minutes, which held fine. Added some dye and 33oz of R134a. The compressor was already filled with 7oz of PAG oil.
AC is blowing at 40F now. Brrrrrr.
Swapping the condenser was a job - I couldn't find much info on Remove and Replace procedures. My Chilton book told me to go give my money to a mechanic. If I wanted to go to a mechanic, I wouldn't have spent my money on a maintenance manual. I get that there are laws and regulations preventing the release of refrigerant into the atmosphere, but they should still include the technical data that I paid for. In my case, there was no refrigerant to release!
07-19-2005, 07:39 PM
If I wanted to go to a mechanic, I wouldn't have spent my money on a maintenance manual. I get that there are laws and regulations preventing the release of refrigerant into the atmosphere, but they should still include the technical data that I paid for. In my case, there was no refrigerant to release!
