Need help with charging A/C system

[Steve McMahan]

I don’t know who you’re taking your car to, but I would go to a place that has a good track record on AC repair. There is a place in Birmingham Alabama called. Southern Armature Works that has a good rep on Yelp. You might give them a call and see what they say.

https://www.southernarmatureworks.com/

 

[kevken1959]

The shop manual shows 1-1/8”. It says to run the engine and ac for 10 minutes so the oil returns to the compressor. Then isolate the compressor, make sure the compressor shaft keyway is facing towards the compressor head and when inserting the dip stick make sure it bottoms against the lower side of the crankcase and not the boss. Afterwards, you need to evacuate the compressor and recharge it.
The 1971 shop manual says the york compressor takes 10 oz of oil and a full charge of r12 is 1.75 lbs. you will need to refer to a conversion chart for 134a. It will take less.
Also, as previously mentioned, if the ambient temp is cool it may not take the full charge but you can heat the refrigerant. The shop should have a tank heater if it’s needed.

Awesome.Thanks! That's very helpful info. "Make sure the compressor shaft keyway is facing towards the compressor head." Is the compressor head the top of the compressor, meaning the keyway would be at the 12:00 position? Kevin.

 

[kevken1959]

I don’t know who you’re taking your car to, but I would go to a place that has a good track record on AC repair. There is a place in Birmingham Alabama called. Southern Armature Works that has a good rep on Yelp. You might give them a call and see what they say.

https://www.southernarmatureworks.com/

Thanks Steve!

 

[cjstaci]

Awesome.Thanks! That's very helpful info. "Make sure the compressor shaft keyway is facing towards the compressor head." Is the compressor head the top of the compressor, meaning the keyway would be at the 12:00 position? Kevin.

Yes, straight up.

 

[raydav]

AC systems are rather simple things. For basic info you might start here: https://en.wikipedia.org/wiki/Carnot_cycle

When I first got interested in auto AC, a pound a R12 at Pep Boys was one dollar.

I have been piecing together old systems. Two things I always do; Replace the old compressors with 508 - there is an adapter from York type.

I have never, and will never, use R134. When R12 got expensive I went to Enviorsafe.

All you need to work on AC is normal tools, a vacuum pump, and a gauge set. And they don't need to cost a lot.

I first do an overnight pressure check with 100# or so of air.

Then vacuum. Both gauge valves open. There is no high or low side when the compressor is not running, so both gauges must read negative. While under vacuum, close both gauge valves.

I then do a functional check with a fluid that is available, cheap, and an excellent refrigerant: propane.

System still under vacuum, attach refrigerant supply. slowly open low side valve. Low side gauge should immediately go positive Take the low side to about fifty pounds. High side should follow. Start compressor - if the system has a pressure actuated switch, the compressor will not start until the low side is at switch set pressure. . Take low side to thirty pounds. High side should climb to one hundred fifty or so.

Replace the propane, or not.

If all that happens, you are done. If not????????????????

 

[kevken1959]

AC systems are rather simple things. For basic info you might start here: https://en.wikipedia.org/wiki/Carnot_cycle

When I first got interested in auto AC, a pound a R12 at Pep Boys was one dollar.

I have been piecing together old systems. Two things I always do; Replace the old compressors with 508 - there is an adapter from York type.

I have never, and will never, use R134. When R12 got expensive I went to Enviorsafe.

All you need to work on AC is normal tools, a vacuum pump, and a gauge set. And they don't need to cost a lot.

I first do an overnight pressure check with 100# or so of air.

Then vacuum. Both gauge valves open. There is no high or low side when the compressor is not running, so both gauges must read negative. While under vacuum, close both gauge valves.

I then do a functional check with a fluid that is available, cheap, and an excellent refrigerant: propane.

System still under vacuum, attach refrigerant supply. slowly open low side valve. Low side gauge should immediately go positive Take the low side to about fifty pounds. High side should follow. Start compressor - if the system has a pressure actuated switch, the compressor will not start until the low side is at switch set pressure. . Take low side to thirty pounds. High side should climb to one hundred fifty or so.

Replace the propane, or not.

If all that happens, you are done. If not????????????????

Good info, Raydav. At the end you say, "Replace the propane, or not." Are you saying it's okay to keep using the propane as refrigerant? What about the flammability? Then I saw this when I looked up Envirosafe: "https://www.justice.gov/opa/pr/envi...unapproved-flammable-hydrocarbon-refrigerants" Has the issue changed since the 2015 ruling? Thanks. Kevin.

 

[raydav]

Good info, Raydav. At the end you say, "Replace the propane, or not." Are you saying it's okay to keep using the propane as refrigerant? What about the flammability? Then I saw this when I looked up Envirosafe: "https://www.justice.gov/opa/pr/envi...unapproved-flammable-hydrocarbon-refrigerants" Has the issue changed since the 2015 ruling? Thanks. Kevin.

A refrigerant moves heat from one place to another. As a high pressure liquid, it is expanded thru a small orifice. That action changes the liquid to gas. And that change attracts heat. It then carries that heat to the condenser, which changes it back to liquid, and that process gives up it's heat to the environment.

For that process to work the refrigerant must be very volatile. Volatile stuff tends to be flammable. But if you get a leak of this stuff, it is not like gasoline that forms a puddle waiting for a match. It flashes off and is gone.

I have read that there are other refrigerants that are flammable.

As for "approved", by who?

I have been buying Envirosafe for over a decade, including recent, for both car and house. The stuff is all over eBay.

And the WEB site: https://www.es-refrigerants.com/?site=dom

I currently have two cylinders. When they are gone I will probably use propane. I have met people who are using it.

 

[kevken1959]

A refrigerant moves heat from one place to another. As a high pressure liquid, it is expanded thru a small orifice. That action changes the liquid to gas. And that change attracts heat. It then carries that heat to the condenser, which changes it back to liquid, and that process gives up it's heat to the environment.

For that process to work the refrigerant must be very volatile. Volatile stuff tends to be flammable. But if you get a leak of this stuff, it is not like gasoline that forms a puddle waiting for a match. It flashes off and is gone.

I have read that there are other refrigerants that are flammable.

As for "approved", by who?

I have been buying Envirosafe for over a decade, including recent, for both car and house. The stuff is all over eBay.

And the WEB site: https://www.es-refrigerants.com/?site=dom

I currently have two cylinders. When they are gone I will probably use propane. I have met people who are using it.

Sounds good. Thanks!

 

[Hemikiller]

The issue with propane as a refrigerant, beyond it being extremely flammable, is when the mechanic installing it doesn't label the system as such. When the AC gets serviced at another shop, the one that uses a recovery system, you now have propane contaminating your refrigerant tanks, or worse, a fire. Been there, done that. Had an 80s conversion van from FL being serviced in CT, and a line failed while performing routine repairs, venting the system into the shop. We evacuated the building, fire department showed up etc. Previous mechanic that had serviced the system charged it with propane, but billed the customer for R12. The shop immediately bought a recovery system that would auto-detect R12 or R134a, and warn if anything else was in the system. This was in the late 90s when R12 was becoming a commodity and shady mechanics were taking advantage of the situation.

For testing purposes, propane is fine, I just wouldn't use it long term.

 

[kevken1959]

The issue with propane as a refrigerant, beyond it being extremely flammable, is when the mechanic installing it doesn't label the system as such. When the AC gets serviced at another shop, the one that uses a recovery system, you now have propane contaminating your refrigerant tanks, or worse, a fire. Been there, done that. Had an 80s conversion van from FL being serviced in CT, and a line failed while performing routine repairs, venting the system into the shop. We evacuated the building, fire department showed up etc. Previous mechanic that had serviced the system charged it with propane, but billed the customer for R12. The shop immediately bought a recovery system that would auto-detect R12 or R134a, and warn if anything else was in the system. This was in the late 90s when R12 was becoming a commodity and shady mechanics were taking advantage of the situation.

For testing purposes, propane is fine, I just wouldn't use it long term.

Thanks!

 

[kevken1959]

A refrigerant moves heat from one place to another. As a high pressure liquid, it is expanded thru a small orifice. That action changes the liquid to gas. And that change attracts heat. It then carries that heat to the condenser, which changes it back to liquid, and that process gives up it's heat to the environment.

For that process to work the refrigerant must be very volatile. Volatile stuff tends to be flammable. But if you get a leak of this stuff, it is not like gasoline that forms a puddle waiting for a match. It flashes off and is gone.

I have read that there are other refrigerants that are flammable.

As for "approved", by who?

I have been buying Envirosafe for over a decade, including recent, for both car and house. The stuff is all over eBay.

And the WEB site: https://www.es-refrigerants.com/?site=dom

I currently have two cylinders. When they are gone I will probably use propane. I have met people who are using it.

So I can tell you hate R134a. In what ways id Envirosafe better?

 

[dtestin]

AC systems are rather simple things. For basic info you might start here: https://en.wikipedia.org/wiki/Carnot_cycle

When I first got interested in auto AC, a pound a R12 at Pep Boys was one dollar.

I have been piecing together old systems. Two things I always do; Replace the old compressors with 508 - there is an adapter from York type.

I have never, and will never, use R134. When R12 got expensive I went to Enviorsafe.

All you need to work on AC is normal tools, a vacuum pump, and a gauge set. And they don't need to cost a lot.

I first do an overnight pressure check with 100# or so of air.

Then vacuum. Both gauge valves open. There is no high or low side when the compressor is not running, so both gauges must read negative. While under vacuum, close both gauge valves.

I then do a functional check with a fluid that is available, cheap, and an excellent refrigerant: propane.

System still under vacuum, attach refrigerant supply. slowly open low side valve. Low side gauge should immediately go positive Take the low side to about fifty pounds. High side should follow. Start compressor - if the system has a pressure actuated switch, the compressor will not start until the low side is at switch set pressure. . Take low side to thirty pounds. High side should climb to one hundred fifty or so.

Replace the propane, or not.

If all that happens, you are done. If not????????????????

Can you give more info on 508? I am thinking of repairing a/c on 71 351c. It hasn't been used for over 20 years.

 

[mrgmhale]

Just a heads up I have not seen mentioned in the prior posts. If you do go to R134, the compressor oil must be changed to a refrigerant oil compatible with R134. The regirant oil used for R12 is NOT compatible with R134.

 

[kevken1959]

So I shared information from the forum with the mechanic and something must have registered because he was able to get the A/C charged and now I have cold air. Many thanks for everyone's input!

 

[cjstaci]

What was the problem?

 

[cv_72mustang]

Yes after 33 posts inquiring minds need to know!

 

[kevken1959]

I wish I could say. On my end I flushed the evaporator, replaced the expansion valve AGAIN, took the quick disconnect valve apart, cleaned it, and put new o-rings in it. I also got the service valves in the right position for him to charge it. On his end, I just don't know. Unfortunately the first time he got Freon in it one of the service valves blew and the he had to do everything over again after replacing the valve. I was so happy he got it done I took another car to him that needed a charge and he got that one done the same day. Maybe he just needed some experience with working with this system. Who knows? I'm just happy to have air now. The only problem is that I'm having problems with one of the connections at the blower switch getting very hot, but OI put that issue in another post. Kevin.

 

[raydav]

So I can tell you hate R134a. In what ways id Envirosafe better?

It is compatible with both R12 and R134 so no issue with seals. And it costs less. And the manufacture advises not to bother vacuuming the system. So you can be a R12, R134 technician with nothing but tools and a gauge set.

 

[raydav]

The issue with propane as a refrigerant, beyond it being extremely flammable, is when the mechanic installing it doesn't label the system as such. When the AC gets serviced at another shop, the one that uses a recovery system, you now have propane contaminating your refrigerant tanks, or worse, a fire. Been there, done that. Had an 80s conversion van from FL being serviced in CT, and a line failed while performing routine repairs, venting the system into the shop. We evacuated the building, fire department showed up etc. Previous mechanic that had serviced the system charged it with propane, but billed the customer for R12. The shop immediately bought a recovery system that would auto-detect R12 or R134a, and warn if anything else was in the system. This was in the late 90s when R12 was becoming a commodity and shady mechanics were taking advantage of the situation.

For testing purposes, propane is fine, I just wouldn't use it long term.

I was asked if I would use propane in a service system. I answered that I probably would. I would NOT put it in any car that had any chance of being serviced by anyone else.

I currently have two Envirosafe cylinders and propane. Until the Envirosafe runs out, on any system I build, I will run propane until I am sure there are no leaks, and then switch to Envirosafe. That should eliminate any loss of expensive refrigerant. And I will try to collect performance comparison data.

If because a line blew off, you pulled everyone out of the shop and called the fire department, that was serious overreaction. Whatever volume was in the system would have flashed off within a few seconds, dispersed, and if you had any ventilation, it would have been not only not been a fire hazard but undetectable.

 

[raydav]

Can you give more info on 508? I am thinking of repairing a/c on 71 351c. It hasn't been used for over 20 years.

Is this enough info? That is a 508, on a 351 C4V. It is sitting on a commercial adapter, right where the old sat. I mounted one on another car with just four small angle brackets I made.

Note, this particular compressor has high and low fittings on the rear that are the same fittings as every gauge set I have.

Look at the bottom of this album.
https://photos.app.goo.gl/r6RWNSzM8ACu4x8x5