R-112 to R-134A

Has anyone used the kit to change a/c freon from 112 to 134? I am doing this on my 1990 Cherokee.
How would you recharge the system for the do it yourselfer?

I believe it's r12. I bought the r134a fittings. I need to find a way to get the old freon out because my jeep won't take anything in.

hupo224 said:

I believe it's r12. I bought the r134a fittings. I need to find a way to get the old freon out because my jeep won't take anything in.

Click to expand...

Did you jump the low pressure switch--if the system is empty the compressor won't cycle.

hupo224 said:

I need to find a way to get the old freon out

Click to expand...

you need to have it evacuated and reclaimed professionally. Any intentional act that releases CFC's into the air is illegal and punishable with a hefty fine.

I'd do my best to avoid giving a nosey neighbor the opportunity to snap a cell phone picture and ruin my day-- just take her to an A.C. shop and let them evacuate it for you.

Ok then what. How do you install the corect freon? It looks like there are two valves on top of the compressor?

you'll want to open the service valves (center the shafts) and jump the low pressure safety switch to get the system to run. Low side port (suction) will draw refrigerant into the system.

If you haven't charged an A.C. system before, you'll want to do some research before you attempt it. You are going to need to pull vacuum and boil out all moisture and contaminants before you introduce the new R134a as it will not carry the old mineral oil in suspension.

Make sure you get either a refrigerant that contains oil suspended in it, or you add the requisite amount of ester (best for retrofitting) oil prior to charging.

Do you open both valves or just the low side?

opening both is the correct procedure because using a manifold gauge package that attaches to the high (discharge) side and low (suction) side to read pressures on both sides of the system is the correct method of charging and evaluating the system.

If you are not using the manifold gauges, you're never going to know when you have the system "full" and operating as designed. When you convert from R12 to R134a, the system capacity listed on the compressor is no longer a valid quantity. The "general" opinion is to charge to about 80% of the R12 capacity, but you'll need to monitor high and low side pressures from there (accounting for ambient air temps) to get things right.

Thanks. I have a manifold gauge but never used one. Now I will give it a wirl.
I live in the country with no noisy neighbors, just the "O"bamas.

I'll remain steadfast in my recommendations to have it professionally evacuated and vacuumed down afterward.

Whether or not you believe there is any merit to the arguments concerning the dangers of CFC's, you still need to get ALL of the old R12 AND the old mineral oil out of the system. You cannot accomplish this by "just opening it up" as the oil will remain in the accumulator and anywhere else it can collect (evaporator and condenser coils) reducing system capacity and reducing efficiency.

If you are already completely out of R-12 freon, you probably would be fine just. I usually replace the accumulator (cheap) and o-rings (cheaper still). You can get a spray can of flush to do your system. Then convert the fittings and add the required amount of oil and R-134a freon. If you still have a charge of R-12, you need to get it recovered. While they are there see how much it would cost to get your system flushed while they are in there. The last time I had a partially filled R-12 evacuated, I got the system evacuated and flushed for only 50 bucks. Considering the flush will run around 10 bucks, it's nearly worth the money to just get it done at the same time.

As for vacuumed, you need to get that done. If you have a air compressor, you can pick up a cheap venturi vacuum pump from Harbor Freight for around 9 dollars. Otherwise, you'll have to get that done professionally as well.

Has anyone found the need to change the rubber lines when converting to R134a?

No, those will be fine.

There is a sticker under my hood saying there is r134a already in there. My dad has those manifold gauges/hoses that you see at the shop. I can "drive" somewhere and let the old freon out I just never used those.


Problem is I cant hook his hoses into the already punctured r134a can I bought. I just have a hose hooked up to it with no gauge.

The can tap that you screwed on the can should have a valve. Shut that and screw the outlet to the line in the middle of the manifold. It normally is yellow. To charge, open the valve on the can, purge the manifold and open the low pressure side to allow the system to suck out the freon. The high pressure side valve should remain closed, but you should still hook it up as the high side is what you watch to see when you have reached full pressure in the system. This is not a complete set of instructions by far, but you should be able to find plenty of resources on the net on how to do everything properly.