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Questions about charging A/C system

J

JoshRountree

NAXJA Forum User
Location
Boone, NC
I replaced my A/C condenser and accumulator two weekends ago and am ready to have a guy charge the A/C system. I told him I was going to take my own refrigerant oil and r134a. I went by the parts store and found the r134a and the oil. My question is how much r134a will I need. It came in 12oz. cans but my manual says it needs 0.567kg or 1.25lbs. I don't know how many cans (approx.) it will take. Any brand better than the other, I was going to get the DuPont brand.

And, refrigerant oil. My manual says SP-20 PAG but couldn't find any. All they had was high, med, and low viscosity with numbers 45, 100, and 150. I'm assuming the numbers match the viscosity. Will the low viscosity work, or should I buy it from the dealer.

Thanks, I printed out the relavent sections from my manual, I hope the guy will test it like the manual says. A/C is one of things you can't do yourself b/c the equipment costs so much...

thanks
 
1.25 lbs is 20 ounces since there is 16 ounces in a pound if you buy 2 cans you will have some waste. most repair shops have the proper machine that can measure the right amount to dispense.
 
jneary said:
1.25 lbs is 20 ounces since there is 16 ounces in a pound if you buy 2 cans you will have some waste. most repair shops have the proper machine that can measure the right amount to dispense.
Click to expand...


Gosh I feel dumb now, I know 16oz is 1lb just didn't think about it....thanks.


What about the refrigerant oil?
 
Josh, with the system completely evacuated like you have you will need to draw a vacuum on the other end to get a good charge. It will make a huge difference on how cold your air will get. You can buy a vacuum pump, either electric or pneumatic but since you don't do this every day I would recommend just finding a shop or a buddy with the equipment.

Hoss
 
HossHoffer said:
Josh, with the system completely evacuated like you have you will need to draw a vacuum on the other end to get a good charge. It will make a huge difference on how cold your air will get. You can buy a vacuum pump, either electric or pneumatic but since you don't do this every day I would recommend just finding a shop or a buddy with the equipment.

Hoss
Click to expand...

Yeah, I'm having someone do it tomorrow but I'm bringing my own r134a and refrigerant oil. I just don't know where to find the SP-20 PAG. I don't know what it's equivalent too.
 
JoshRountree said:
I replaced my A/C condenser and accumulator two weekends ago and am ready to have a guy charge the A/C system. I told him I was going to take my own refrigerant oil and r134a. I went by the parts store and found the r134a and the oil. My question is how much r134a will I need. It came in 12oz. cans but my manual says it needs 0.567kg or 1.25lbs. I don't know how many cans (approx.) it will take. Any brand better than the other, I was going to get the DuPont brand.

And, refrigerant oil. My manual says SP-20 PAG but couldn't find any. All they had was high, med, and low viscosity with numbers 45, 100, and 150. I'm assuming the numbers match the viscosity. Will the low viscosity work, or should I buy it from the dealer.

Thanks, I printed out the relavent sections from my manual, I hope the guy will test it like the manual says. A/C is one of things you can't do yourself b/c the equipment costs so much...

thanks
Click to expand...

BS on your last statement, you can and should do it yourself, and the tools aint expensive. Mechanics just want you to think they are. See if this helps you out. http://www.naxja.org/forum/showthread.php?t=930084 You can rent a vacuum pump (all you really need) from autozone for free. All you have to do is run it for thirty mins, turn off but leave hooked up for thirty mins, then unplug it from the port and then charge with a reqular "quick-fill" can. You need 16oz of r134 and 6oz of oil, no more no less. SP20 is equivalent to ISO 135; 150 or 100 will do you right, I went with 150. Invest in some good quality "double end capped" oil with UV dye.

here's where the problems start:

1stly, your evaporator is almost certainly shot. You can replace it for $78 with a new part from ACKits.com and r134 is a greenhouse gas. It will also help you save some green.

2ndly, neither vacuuming nor leaking will remove all the old oil from your system. You need to get it out. Get an air compressor and some flushing solvent. For the condenser and accumulator, dump in some solvent then blow it out, repeat.

remove the valve core from the low-pressure sensor bung in the accumulator, drain overnight upside-down.

remove your compressor, drain overnight upside-down.

Reinstall everything (with new o-rings, they're cheap and easy to replace), except the accumulator valve core. Now add three oz oil each to the compressor and the accumulator. manually turn the compressor clutch 20-50 times to get the oil to start to circulate. Replace the accumulator valve core and sensor.

pull vaccuum.

add the r134 with the engine on and ac at full blast recirc with all the doors open.

Your AC system now works like it did from the factory, enjoy.
 
darjevon said:
BS on your last statement, you can and should do it yourself, and the tools aint expensive. Mechanics just want you to think they are. See if this helps you out. http://www.naxja.org/forum/showthread.php?t=930084 You can rent a vacuum pump (all you really need) from autozone for free. All you have to do is run it for thirty mins, turn off but leave hooked up for thirty mins, then unplug it from the port and then charge with a reqular "quick-fill" can. You need 16oz of r134 and 6oz of oil, no more no less. SP20 is equivalent to ISO 135; 150 or 100 will do you right, I went with 150. Invest in some good quality "double end capped" oil with UV dye.

here's where the problems start:

1stly, your evaporator is almost certainly shot. You can replace it for $78 with a new part from ACKits.com and r134 is a greenhouse gas. It will also help you save some green.

2ndly, neither vacuuming nor leaking will remove all the old oil from your system. You need to get it out. Get an air compressor and some flushing solvent. For the condenser and accumulator, dump in some solvent then blow it out, repeat.

remove the valve core from the low-pressure sensor bung in the accumulator, drain overnight upside-down.

remove your compressor, drain overnight upside-down.

Reinstall everything (with new o-rings, they're cheap and easy to replace), except the accumulator valve core. Now add three oz oil each to the compressor and the accumulator. manually turn the compressor clutch 20-50 times to get the oil to start to circulate. Replace the accumulator valve core and sensor.

pull vaccuum.

add the r134 with the engine on and ac at full blast recirc with all the doors open.

Your AC system now works like it did from the factory, enjoy.
Click to expand...


I guess I should have said but I have a 1998, and the AC actually worked pretty well before I had it discharged. The only reason I replaced the condenser and accumulator was because someone backed into me and busted my radiator. I hope the other parts are in good shaped. I'm going to take it to this guy tomorrow, but might rent the tool the next time. I'd much rather do it myself, just didn't think about renting the tool.
 
I paid $148.24 yesterday for replace the two seals between the manifold and compressor, evacuate and recharge of the system. I have the know how, but not the tools nor the time to do this job myself.

Tom
 
darjevon said:
2ndly, neither vacuuming nor leaking will remove all the old oil from your system. You need to get it out. Get an air compressor and some flushing solvent. For the condenser and accumulator, dump in some solvent then blow it out, repeat.

remove the valve core from the low-pressure sensor bung in the accumulator, drain overnight upside-down.

remove your compressor, drain overnight upside-down.
Click to expand...
I worked in dealerships for more than 20 years, and went to several manufacturers' A/C schools.
Nobody ever recommended that procedure. Certainly nobody said that you need to get all the old oil out except in the case of some R12 to R134a conversions.
Take it to a qualified A/C specialist.
 
JoshRountree said:
I guess I should have said but I have a 1998, and the AC actually worked pretty well before I had it discharged. The only reason I replaced the condenser and accumulator was because someone backed into me and busted my radiator. I hope the other parts are in good shaped. I'm going to take it to this guy tomorrow, but might rent the tool the next time. I'd much rather do it myself, just didn't think about renting the tool.
Click to expand...

shouldnt the person who backed into you have their insurance carrier cover the cost to have it fixed.
 
89xj said:
shouldnt the person who backed into you have their insurance carrier cover the cost to have it fixed.
Click to expand...

haha, you're not the first one to mention this. I was over at a friend's house one night and someone I didn't know backed into my front end as they left, and ran off. I called the sherrif's dept. and tried to report but they said they couldn't do much. I called the guy and confronted him and he denied it. My parents paid for my insurance at the time and I didn't ask, and my father didn't tell me that I had collision, so it's too late to report it. I just fixed it myself and chaulked it up to a life lesson...

I ended up replacing the radiator, condenser, accumulator, water pump, t-stat, t-stat housing, and all the hoses...
 
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