R12 to 134
Senior Member
Joined: Jul 2007
Posts: 3,805
Likes: 480
From: Cape Girardeau MO
Venting the old freon to atmosphere is not legal - but that's between you and your environmental conscience.
I changed mine over about 10 years ago - from what I can recall -
1) Changed the drier to one with an R134 rating. Need a special clip tool to get the hose off.
2) Changed all the o-rings - the new ones were bluish-green or green, the originals were black
3) Flushed the system with an appropriate cleaner to get the old refrigerant oil out.
4) Removed the compressor and flushed to get the old refrigerant oil out.
5) Changed the orifice to one recommended for R134. Need a special extraction tool for this.
6) Installed a high-pressure switch in series with the existing low pressure switch. This is not necessary - just a concern of mine at the time when conversions were still relatively new, and not a lot of information was available.
7) Pulled a vacuum for about 30 minutes to be sure to get all the moisture out, particularly after the flush.
8) Put in the prescribed amount of R134 compatible oil. Added freon at a rate of 3/4 lb R134 per pound of spec'd R12, then fired things up and dialed things in by pressure - trying to get about 40psi on the low side, and not over 300psi on the high side.
As luck would have it - the compressor was making a little noise before the conversion, and it shelled out a couple of months after the conversion - so got to flush the system again, as well as change the orifice and compressor.
Since then, been working good - not quite as cold as the R12, but just have to kick the fan speed up a notch to keep things comfortable. Lose about 1/2 can per year - which is acceptable to me, given the age of the original components and hoses.
As always - please be careful. The high pressures and extreme temperatures involved with A/C work can damage equipment and people in a hurry.
I changed mine over about 10 years ago - from what I can recall -
1) Changed the drier to one with an R134 rating. Need a special clip tool to get the hose off.
2) Changed all the o-rings - the new ones were bluish-green or green, the originals were black
3) Flushed the system with an appropriate cleaner to get the old refrigerant oil out.
4) Removed the compressor and flushed to get the old refrigerant oil out.
5) Changed the orifice to one recommended for R134. Need a special extraction tool for this.
6) Installed a high-pressure switch in series with the existing low pressure switch. This is not necessary - just a concern of mine at the time when conversions were still relatively new, and not a lot of information was available.
7) Pulled a vacuum for about 30 minutes to be sure to get all the moisture out, particularly after the flush.
8) Put in the prescribed amount of R134 compatible oil. Added freon at a rate of 3/4 lb R134 per pound of spec'd R12, then fired things up and dialed things in by pressure - trying to get about 40psi on the low side, and not over 300psi on the high side.
As luck would have it - the compressor was making a little noise before the conversion, and it shelled out a couple of months after the conversion - so got to flush the system again, as well as change the orifice and compressor.
Since then, been working good - not quite as cold as the R12, but just have to kick the fan speed up a notch to keep things comfortable. Lose about 1/2 can per year - which is acceptable to me, given the age of the original components and hoses.
As always - please be careful. The high pressures and extreme temperatures involved with A/C work can damage equipment and people in a hurry.