IMHO......IF the system is still under R-12 pressure (and/or was not functioning)….you’ll be ahead of the game.…if you take it to a pro. Find out, if it only needs to be topped off or, if there is a leak or, if the compressor is up to the job. A pro, can test the compressor and usually has the tools to test for leaks, using a dye or with an elec. sniffer. IF you decide to proceed w/ a DIY CONVERSION job, you’ll now KNOW what part(s) will be needed and the system will still need to be evacuated anyway. The machine to recover R-12 is expensive and it is against the law to vent R-12 into the atmosphere. So, let the pro do that part.
Once void of refrigerant......you could DIY the parts replacement part.
IF you know that a part is bad……now (during the conversion), will be the time to replace it. IF the compressor has failed, you‘ll need a new one and YOU’LL NEED TO FLUSH.*
The usual conversion, will require the removal of the accumulator, orifice tube, and old compressor (w/clutch). Drain the oil from the old compressor and note the amount. Drain the oil from the old accumulator and note the amount. Dump the old accumulator and orifice tube, buy new ones.
Talk to the parts counter guy about your conversion......make sure that the desiccant in the accumulator is for R-134a. And, ask IF you'll need to replace the low pressure switch and/or change colors on your new orifice tube (to be compatible with the switch to R-134a). They may have it listed.
DO NOT expose the new accumulator to air.........keep the shipping caps on. Even when it's installed and hooked up to the lines.......the accumulator will draw moisture out of what little air is in the lines. For that reason, do the re-charge immediately........or at least that day.
The old compressor can be re-used if serviceable. Do not flush a compressor.
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Hummm……To FLUSH or NOT, you decide.
One of the reasons for a flush of the remaining components.....is that, as much as possible, you want to clear the “crud” and old oil out of the system. I wouldn't want to mix mineral oil used in an R-12 system with the oil needed for an R-134a system. But, that's just me.
So…..the evaporator and condenser can be flushed in place (or removed and flushed)......be careful. You could also flush the lines.......but, flushing a line w/a muffler is not recommended. So, you could buy a replacement hose w/ a new muffler or skip that line/part.
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As long as MOST (say more than half) of the old mineral oil is removed and IF there was NO compressor failure…..according to the Haynes book: "Unless the vehicle manufacturer - or the aftermarket kit instruction sheet specifically recommends flushing the system during the retrofit procedure, you can assume that flushing is not necessary (Readers who obtain the SAE's J1661 document will note that it recommends flushing before retrofit. However, you can disregard this information because the SAE no longer believes that flushing is critical to a successful retrofit.)"
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Anyway.....replace all the old "O" rings with new green "O" rings. Use Nylog as a lube (ask the parts guy for the correct one).
As for AC oil….use the correct compatible type and weight, keeping in mind the particular manufacturer of the AC system and refrigerant type. Oil is added into the individual parts as they are installed. How much oil? The answer varies. A good book on the subject will help.
Install all of the parts and connect up all of the lines and hoses. Once everything is back into its place..........you'll need to add on the new R-134a adaptors and label the system w/ a R-134a conversion sticker (so, the next guy will know).
Then proceed with your re-charge procedure.
Full Re-charge:
http://www.explorerforum.com/forums/...d.php?t=158183
Note: System pressures and capacities will vary between mfns and applications (again, a good book will help).
Ford Conversion Notes:
My '94 Explorer (w/ factory R-134a) used a blue orifice tube. I’ve heard that previous years (R-12 systems), used a red orifice tube. Normally......I figure, IF the factory system worked well w/ whatever colored tube......then, I should replace the tube w/ a like colored tube. Thinking - that the orifice color, indicates a certain sized hole. But, in this case (R-12 to R-134a conversion) a switch from red to blue orifice tube might be the correct choice.
Also, check that the low pressure switch is the correct one for your application. NAPA lists different part numbers for an R-12 vs. R-134a system (remember to also check the elec. connectors).
Shamaal said:
The switch on the accumulator controls the clutch on the compressor. When the system pressure is less than 24.5 psi the clutch is disengaged. When the pressure is greater than 43.5 psi the compressor clutch engages.
And, as a COMPARISON ONLY.......the Haynes book says ('94 Ford Explorer w/factory R-134a system)........at ambient air temp of 80 degrees F, hi velocity fan in front of the condenser, 1500 RPM.........22-50 low side and 160-250 high side pressure. Capacities: oil 7 oz and R-134a 2.25 lbs (36 oz).**Conversion capacities will differ, for a R-134a conversion, I've heard figures anywhere from 60-90% of the R-12 charge was good. **
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Aloha, Mark
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