AC charging

[77jimmy]

Hi I just got all my AC working. I need to know how to fill it up with freon. It's R-12. I have 8 cans of R-12 and the tool for the cans. But not pressure gauge. Can I do it without one? Or does someone have one for the R-12 I can buy. Or how can I change it to R-134a?

 

[wildcatjason]

Weeellll how do you know it's working without freon is my question? You have to vacuum it down and it has to hold the suction to know its working properly. The freon gets applied in this process and you know it's working if the system holds vacuum. You have to clean out/replace the whole system to update your freon. I guess there is a freeze 12 that is compatible with both types of freon but if you already have the r12 that shouldnt be a problem.

 

[77jimmy]

Well what I ment was that I got the blower motor fix and now I just need to know how much freon it needs. It blows semi cold. It's a 77 jimmy that had no factory air but it has a surburban rear AC unit in it. How much freon do I need to put in it? And how do I know if I over charge it?

 

[oneluckypops]

Honestly, not trying to insult you in anyway but, A/C systems can be very dangerouse to service, I dont reccomend ANYONE perform a/c work unless they are properly trained and have the right tools for the job. If i was you I would take it to a professional and let them charge it for you.

you have to have a set of gauges to install the freon and to check your pressures, an infrared thermometer is also very usefull for diagnosing systems air flow, under/over charging, and blockages.

 

[77jimmy]

Well that was of no help. I know there tricky but not all that hard. I just need to know how much freon in. Not all of us have the money to take our trucks in.

 

[HotRodPC]

To be honest with you, I bet you can sell that R12 on CL for $25 a can. Sell 4 cans for $100, then take your truck to service place and usually an AC check up is $59.95-$79.95 and includes 1lb of freon, probably more for R-12 but see if they'll use one of your cans and keep the price the same.

 

[wildcatjason]

If you don't have the proper equipment to deal with the ac they are not tricky they are impossible. I will do everything from body to engine work but I don't have the equipment to mess with it so I would take it somewhere and let them suck it down and fill it, but to answer your question it 5lbs 4 oz for a my suburban with front and rear ac. I'm under the impression that they need to vacuumed down to about 30 mmhg prior to filling. I could be wrong.

 

[77jimmy]

Hey hotrod that's a good idea thanks. I'm going to give it a try. If I can't get it cold. I'm going to add a can slowly to see if it start blowing cold. I have the tool to add the Freon and a adapter so that I can use my gauge for r134a.

 

[77jimmy]

Well it's blowing Ice cold now. I added about 3/4 of a can. It's at 32psi. Thank for all the tips.

 

[HotRodPC]

Good to know. Hope it holds up for you and doesn't leak out.

 

[oneluckypops]

Well it's blowing Ice cold now. I added about 3/4 of a can. It's at 32psi. Thank for all the tips.

and yet you still dont have a clue what the head pressure is running, hope it holds up for you.

 

[Guardian]

I was thinking the same thing. If there is a restriction it won't last long, none of the old compressors had a pressure relief but some of the remans do.

 

[Boudin]

Most of the gauge sets I have seen that are automotive have both r-12 and r-134a markings on them. I too am running r-12 in my 84 C20. You need to do it right or have someone else do it for you. There is a lot more to a/c work than just shooting in more freon in hopes of making it colder. Freon is usually the last thing I check out when trying to get an older a/c system working properly. Make sure that your condensor coil is free of bugs and junk.....check for leaking duct work.....use a thermometer to read the temp of the air coming out the vents and compare it to the air temp that it is taking in. You should see a 40 degree drop at least. When doing it at idle, you want to allow the truck to run on NORM so you can use the outside temp as a reference and after running the a/c for a few minutes, take the temp of the air at the vents. This is best done with a good high volume fan placed in front of the radiator to simulate air flow when driving and the engine should be revved to about 1500-2000 rpm when reading the vent temp.

With r-134a cans running 30 bucks at the parts store and vintage cans of r-12 for the same price on eBay, i decided to stick with r-12 and not do the conversion. There is the advantage of r-12 systems cooling better than using 134a in the same system.

If you have freon loss....you have a leak, pure and simple. Fix it before you even think about adding freon to it.

 

[HotRodPC]

Most of the gauge sets I have seen that are automotive have both r-12 and r-134a markings on them. I too am running r-12 in my 84 C20. You need to do it right or have someone else do it for you. There is a lot more to a/c work than just shooting in more freon in hopes of making it colder. Freon is usually the last thing I check out when trying to get an older a/c system working properly. Make sure that your condensor coil is free of bugs and junk.....check for leaking duct work.....use a thermometer to read the temp of the air coming out the vents and compare it to the air temp that it is taking in. You should see a 40 degree drop at least. When doing it at idle, you want to allow the truck to run on NORM so you can use the outside temp as a reference and after running the a/c for a few minutes, take the temp of the air at the vents. This is best done with a good high volume fan placed in front of the radiator to simulate air flow when driving and the engine should be revved to about 1500-2000 rpm when reading the vent temp.

With r-134a cans running 30 bucks at the parts store and vintage cans of r-12 for the same price on eBay, i decided to stick with r-12 and not do the conversion. There is the advantage of r-12 systems cooling better than using 134a in the same system.

If you have freon loss....you have a leak, pure and simple. Fix it before you even think about adding freon to it.

No my friend, a memember on here just did his own leg work on his parts, freon, oil etc and then took it to someone and paid them labor. He got freon for $8 a can at Big Lots. I've checked, it is $8 for 12oz cans of R134a, and $10 a can if you want leak sealer in it too. I'm going to Big Lots today and getting 6 cans for my 2 trucks that need it. One is already converted the other is not as of yet. I do have an Air Vac though and intend to Vacuum my systems down and borrow some guages.

 

[HotRodPC]

I've hit this guy up via email and see if he'll take $75 for these guages.
http://oklahomacity.craigslist.org/tls/3021405718.html

Anyone know how well an Air Vac works? I have one for R12. The type where you use an air compressor to create your vacuum? I think I'll try using it to vacuum down my R12 truck, then install the R134a conversion adapters and fill it with R134a. If I undestand right, since R134a runs a higher pressure, you only fill to about 85% of capacity what's called for on R12 right??? I've only done AC 2X in my life long long ago and that was with someone who knew what the hell they were doing. But, I think I can handle this if i get those guages. Going to Big Lots now to get that $8 freon.