R-12 to 134A A/C conversion
- Thread starter azcode3gn
- Start date
captndave737
Well-Known Member
- Joined
- Feb 14, 2006
I converted mine a few years ago and it was the best move I ever made. When done right it's as cold or colder than R12.
I'm currently in Brazil but when I get home next week I'll send a detailed description.
You should have AC guages, a thermometer and a vacuum pump. You'll need a new drier and expansion valve (cheap), AC flush and some oil (pag I think but I'll check) in addition to the r 134.
I'm currently in Brazil but when I get home next week I'll send a detailed description.
You should have AC guages, a thermometer and a vacuum pump. You'll need a new drier and expansion valve (cheap), AC flush and some oil (pag I think but I'll check) in addition to the r 134.
You need to recover the R12 out of the system first and foremost
Then replace the reciever-drier, orifice tube, AFTER flushing the system out with AC flush chemical (available at parts stores).
Install the R12-134a connectors.
Now you need to either borrow or rent a vaccum pump or take the car to a repair facility
Vaccum the the system down for at least 1 hour to remove the remaining oil and boil out any moisture of the system. You normaly do only 15 minutes to 30 minutes with a normal AC repair with evac/recharge but you need to get all of the old oil and moisture out of the system.
Then replace the reciever-drier, orifice tube, AFTER flushing the system out with AC flush chemical (available at parts stores).
Install the R12-134a connectors.
Now you need to either borrow or rent a vaccum pump or take the car to a repair facility
Vaccum the the system down for at least 1 hour to remove the remaining oil and boil out any moisture of the system. You normaly do only 15 minutes to 30 minutes with a normal AC repair with evac/recharge but you need to get all of the old oil and moisture out of the system.
- Joined
- May 26, 2001
If you expect to drive your GN here during the summer, changing to 134a is not going to do the job of cooling your car properly.
First of all, 134a is only 80% efficient as R-12, so in a "converted system", it will NOT cool as well. The Regals in 1987 do not have the larger evaporators and condensers like late model cars using 134a that do cool well.
Maybe at night or less than 100 deg. days it will not be too bad, but those 110 deg. spans of a few weeks will not comfortable.:smile:
First of all, 134a is only 80% efficient as R-12, so in a "converted system", it will NOT cool as well. The Regals in 1987 do not have the larger evaporators and condensers like late model cars using 134a that do cool well.
Maybe at night or less than 100 deg. days it will not be too bad, but those 110 deg. spans of a few weeks will not comfortable.:smile:
Mr-SShadow
New Member
- Joined
- Jul 7, 2007
My monte was conveted to 134a by previous owner. It pretty much sucks during the summer. I can barley feel the cool air. During winter its cold at night tho LoL.
Yes it is true that evaporative tempartures of R134a are not the same as R12. Therefore, 134a uses larger condensors and evaporators and poorly converted systems show that in spades. However, a properly retrofitted vehicle should give you acceptable cooling- if I had to put a precentage on it I would say cooling would be with in 90% or better just not 100%.
Yes you can upgrade the condenser core count (thicker) or dimensionaly larger (width) for added refrigerant charge, and adding a pusher fan to force more air flow across the condenser.
However, with your symptoms I would fathom a guess that you have a saturated desecant material in your reciever drier allowing moisture in the system, a clogged orfice tube not regulating refrigerant, or low charge.
Most shops that do retrofits, don't flush the ester oil and lines out. Nor do they usually replace the drier or accumulator. Its usually just a hack job of recover R12, screw some fittings on, 10 minute vac. and charge 134a. All wich lead to par or sub par cooling.
Also don't forget that the basics- it may be not cooling just from normal failures, weak/worn compressor, leak/low charge, etc.
Yes you can upgrade the condenser core count (thicker) or dimensionaly larger (width) for added refrigerant charge, and adding a pusher fan to force more air flow across the condenser.
However, with your symptoms I would fathom a guess that you have a saturated desecant material in your reciever drier allowing moisture in the system, a clogged orfice tube not regulating refrigerant, or low charge.
Most shops that do retrofits, don't flush the ester oil and lines out. Nor do they usually replace the drier or accumulator. Its usually just a hack job of recover R12, screw some fittings on, 10 minute vac. and charge 134a. All wich lead to par or sub par cooling.
Also don't forget that the basics- it may be not cooling just from normal failures, weak/worn compressor, leak/low charge, etc.
Yes Certainly R12 cools better there is no doubt about that... but an R134a system works very well too. Its that apples and oranges thing you know? :biggrin: :tongue:
The down side to recharging with R12 is the cost. I can still get R12 no problem... the problem is MY cost is nearly $30 per 11 oz CAN... figure you need at least 3-4 cans thats $120 MY COST not retail... when my cost for 3-4 lbs. of R134a is $40!
Thats ALOT of coin to be letting seep out into Al Gore's Global climate change world if you have a leak!
The down side to recharging with R12 is the cost. I can still get R12 no problem... the problem is MY cost is nearly $30 per 11 oz CAN... figure you need at least 3-4 cans thats $120 MY COST not retail... when my cost for 3-4 lbs. of R134a is $40!
Thats ALOT of coin to be letting seep out into Al Gore's Global climate change world if you have a leak!
Check the cabin air filters if they have them.
You can tell spring is in the air by the # of threads on converting to R-134a. My 2cents worth. I always said I would convert when the existing compressor went out. 3 years ago I had the opportunity and it was a learning exprience.
I tested tested "Common wisdom" on R-134a learned there is only one way to charge the system. Look up he P-T chart for the evaporator temp and charge the system to that pressure. Also you have to change the orfice tube for R-134A to get the temps down. While you're doing it change the o-rings too so it will stay charged.
I initially charged the system to the values suggested by "common wisdom" 80% of the R-12 charge by weight. At this charge the pressures were similar to R-12 but the temperature was not. Discharge temperature at the vents was 75 degrees on a 95 degree day. High side pressure was 200psi lowside was 20.
When I raised the pressures to what they should be for R-134a 270 psi highside. The discharge temp dropped to 50 degrees and it cooled well.
The only dowside of an R-134a conversion is that it takes longer to get cold. At least in my experience.
I tested tested "Common wisdom" on R-134a learned there is only one way to charge the system. Look up he P-T chart for the evaporator temp and charge the system to that pressure. Also you have to change the orfice tube for R-134A to get the temps down. While you're doing it change the o-rings too so it will stay charged.
I initially charged the system to the values suggested by "common wisdom" 80% of the R-12 charge by weight. At this charge the pressures were similar to R-12 but the temperature was not. Discharge temperature at the vents was 75 degrees on a 95 degree day. High side pressure was 200psi lowside was 20.
When I raised the pressures to what they should be for R-134a 270 psi highside. The discharge temp dropped to 50 degrees and it cooled well.
The only dowside of an R-134a conversion is that it takes longer to get cold. At least in my experience.
