r12 to r134 a/c freon change over
04-10-2015, 02:37 PM
#1
Racer
Thread Starter
r12 to r134 a/c freon change over
Hi, need help. Have a 1967 with factory air that hasn't blown cold for many many years. Thinking the best bet is to switch over to r134 because it is plentiful and way cheaper than r12( $100 lb).I am getting my original drier rebuilt with x7 for r134. This is where I am getting confused,after reading 50-100 threads on this subject I am confused. I have spoken to 2 different company's ,I guy( a/c shop only) with over 50 yrs experience and another corvette specialty shop that has done 100/200 of these conversions over the years. From what I have read everyone claims you have to switch over to green o rings for the r134. However the specialty shop claims he has never changed the original black o rings in all the conversions he's done without any leaks or issues.I know you have to flush system, drain the mineral oil in compressor and add ester oil, add new drier and adjust POA valve to 22lb psi.,then add the r134. Also I want to get the front seal on the compressor replaced. What is a better seal the original ceramic or the two lip seal that rides on the compressor shaft.
04-10-2015, 03:31 PM
#2
Race Director
Hi, need help. Have a 1967 with factory air that hasn't blown cold for many many years. Thinking the best bet is to switch over to r134 because it is plentiful and way cheaper than r12( $100 lb).I am getting my original drier rebuilt with x7 for r134. This is where I am getting confused,after reading 50-100 threads on this subject I am confused. I have spoken to 2 different company's ,I guy( a/c shop only) with over 50 yrs experience and another corvette specialty shop that has done 100/200 of these conversions over the years. From what I have read everyone claims you have to switch over to green o rings for the r134. However the specialty shop claims he has never changed the original black o rings in all the conversions he's done without any leaks or issues.I know you have to flush system, drain the mineral oil in compressor and add ester oil, add new drier and adjust POA valve to 22lb psi.,then add the r134. Also I want to get the front seal on the compressor replaced. What is a better seal the original ceramic or the two lip seal that rides on the compressor shaft.
Do not need to flush the system, but need to drain and blow all the old oil out. ESTER oil (versus PAG) is more forgiving of any residual mineral oil.
The ceramic seal AC #15-2191 (formerly #15-210) or GM #6599114 should be all you need.
www.autoacforum.com has excellent info on flushing, and converting from R12 to R134a if you want additional info. This is a great site. See the FAQ Section.
R12 is not $100 a pound unless that is the cost some AC shop is telling you to get your $$$. It is more like $25-30 per pound on Ebay. But that is your choice to make.
Larry
Last edited by Powershift; 04-10-2015 at 03:33 PM.
04-10-2015, 05:55 PM
#4
Race Director
Some more info for you: from EPA and from GM. After many years, they have found that the sky does not fall if you change refrigerants. The REVISED procedures below reflect this. However, I still recommend R12 for our older cars. However, both will work.
http://www.epa.gov/ozone/title6/609/.../retrguid.html
http://www.e38.org/pparish/gm-rp.htm
Larry
http://www.epa.gov/ozone/title6/609/.../retrguid.html
http://www.e38.org/pparish/gm-rp.htm
Larry
Last edited by Powershift; 04-10-2015 at 06:00 PM.
04-10-2015, 10:13 PM
#5
Melting Slicks
IMO..134A wont touch R-12 in an old system. You couldn't pay me enough to change one of "my" old systems to 134A.
And even if R12 was $100 a lb. (it isn't), I'd gladly pay it for the difference in cooling. If the tech says other wise...I'd find another tech. Many techs these days have never charged a single can of R-12....and know less than nothing about the old system capabilities.
...oops I forgot you asked about o-rings. Install new O-rings throughout whatever refrigerant you use. I use the green ones for everything. ..... "and" do all the stuff ghostrider mentioned below.
And even if R12 was $100 a lb. (it isn't), I'd gladly pay it for the difference in cooling. If the tech says other wise...I'd find another tech. Many techs these days have never charged a single can of R-12....and know less than nothing about the old system capabilities.
...oops I forgot you asked about o-rings. Install new O-rings throughout whatever refrigerant you use. I use the green ones for everything. ..... "and" do all the stuff ghostrider mentioned below.
Last edited by Stan's Customs; 04-10-2015 at 10:26 PM.
04-10-2015, 10:19 PM
#6
I'm no expert, but do all my own A/C work.
If the system has been left unpressurized for many years, your only option is to replace all the O-rings. If not, you will be chasing slow leaks all the time.
The system should be flushed. I use denatured alcohol, poured into the lines and blown through. Repeat until it flows clear.
Get your compressor inspected, a new or rebuilt receiver drier, and use R-12. Get it off Ebay. You can buy a gauge set for 50-75 bucks and service yourself. Follow the instruction for oil and the freon charge.
I would also have our STV cleaned/rebuilt and of course a new filter.
If the system has been left unpressurized for many years, your only option is to replace all the O-rings. If not, you will be chasing slow leaks all the time.
The system should be flushed. I use denatured alcohol, poured into the lines and blown through. Repeat until it flows clear.
Get your compressor inspected, a new or rebuilt receiver drier, and use R-12. Get it off Ebay. You can buy a gauge set for 50-75 bucks and service yourself. Follow the instruction for oil and the freon charge.
I would also have our STV cleaned/rebuilt and of course a new filter.
06-11-2015, 09:58 AM
#7
Burning Brakes
I have a set of gauges I used to use to service AC in airplanes. Never used it on my Vette, because R-12 now requires recovery systems and all that.
That said, i still remember how to do it, even though that was, um, well over 30 years ago. But I do recall taking air out of the system with a vacuum pump -- is that not needed in these systems as well?
I druther put R-12 in it and not have the expense and bother of changing over to the new stuff (which apparently doesn't even cool as well). And I could DIY it with a vacuum pump. But the shop I called yesterday said they are away from R-12 because of the expense of the stuff, plus the expense of the equipment to do the servicing.
I can't imagine I'll put a hole in the ozone layer with my old equipment, servicing it once every 10 years.
That all said, just in case, does anyone have specific info on converting a C4?
That said, i still remember how to do it, even though that was, um, well over 30 years ago. But I do recall taking air out of the system with a vacuum pump -- is that not needed in these systems as well?
I druther put R-12 in it and not have the expense and bother of changing over to the new stuff (which apparently doesn't even cool as well). And I could DIY it with a vacuum pump. But the shop I called yesterday said they are away from R-12 because of the expense of the stuff, plus the expense of the equipment to do the servicing.
I can't imagine I'll put a hole in the ozone layer with my old equipment, servicing it once every 10 years.
That all said, just in case, does anyone have specific info on converting a C4?