Building an A/C system from near scratch

[KBScobravert]

^^^^^^yep I see it flare back in right past the tube.

[dville_gt]

now you can see why i felt it easiest to stay "all GM" with it!

[KBScobravert]

now you can see why i felt it easiest to stay "all GM" with it!

Yep.....but I am gonna have to keep the Ford Evaporator and compressor. I am NOT pulling the dash every again and think it would be too much trouble to cram a GM compressor where the Ford one sits. Three of the bolt holes look to be in the same spot, but the lines come out towards the rack and I am not sure they would clear.

[dville_gt]

Yep.....but I am gonna have to keep the Ford Evaporator and compressor. I am NOT pulling the dash every again and think it would be too much trouble to cram a GM compressor where the Ford one sits. Three of the bolt holes look to be in the same spot, but the lines come out towards the rack and I am not sure they would clear.

oh i don't blame you, i just say that because people gave me a hard time for grafting a new bottom on my heater box just to use the gm evap. to me it was worth it to keep all the same connections, etc. and obviously i needed to stay with the gm compressor.

i think your system will come out great.

[shumpertdavid]

dville gt, The accumulator needs to be mounted upright to help control oil return back to the compressor for lubrication. I was at an a\c class last night for work when all this was explained. The oil will puddle in the bottom of the accumulator, because the freon leaving the accumulator is a vapor/gas it will not carry the oil back to lubricate the compressor. There is a .040 orifice made into the internal line that sits in the oil at the bottom. It allows oil to weep into the line and then the freon vapor will push it back to the compressor. Your location my still allow it to function properly, but based on the illustration I saw I don't believe it does. Long term if it doesn't it will starve the compressor for oil and cause it to have problems. Also by system design on all a\c systems, with r-134-a, being undercharged by as little as 10% will cause a lubrication carrying loss of 50%.

I'm not trying to talk you into changing your system up, just merely giving you some info so that if it has problems you can possibly help diagnose why and help ensure success the next go round.

I learned a lot of info last night that explains random failures that I've seen over the last 15 years.

[Magnimike1]

dville gt, The accumulator needs to be mounted upright to help control oil return back to the compressor for lubrication. I was at an a\c class last night for work when all this was explained. The oil will puddle in the bottom of the accumulator, because the freon leaving the accumulator is a vapor/gas it will not carry the oil back to lubricate the compressor. There is a .040 orifice made into the internal line that sits in the oil at the bottom. It allows oil to weep into the line and then the freon vapor will push it back to the compressor. Your location my still allow it to function properly, but based on the illustration I saw I don't believe it does. Long term if it doesn't it will starve the compressor for oil and cause it to have problems. Also by system design on all a\c systems, with r-134-a, being undercharged by as little as 10% will cause a lubrication carrying loss of 50%.

I'm not trying to talk you into changing your system up, just merely giving you some info so that if it has problems you can possibly help diagnose why and help ensure success the next go round.

I learned a lot of info last night that explains random failures that I've seen over the last 15 years.

Explained quite well. I have taught a few simple classes and attended some more intense ones myself.

[Baron Von Crowder]

dville gt, The accumulator needs to be mounted upright to help control oil return back to the compressor for lubrication. I was at an a\c class last night for work when all this was explained. The oil will puddle in the bottom of the accumulator, because the freon leaving the accumulator is a vapor/gas it will not carry the oil back to lubricate the compressor. There is a .040 orifice made into the internal line that sits in the oil at the bottom. It allows oil to weep into the line and then the freon vapor will push it back to the compressor. Your location my still allow it to function properly, but based on the illustration I saw I don't believe it does. Long term if it doesn't it will starve the compressor for oil and cause it to have problems. Also by system design on all a\c systems, with r-134-a, being undercharged by as little as 10% will cause a lubrication carrying loss of 50%.

I'm not trying to talk you into changing your system up, just merely giving you some info so that if it has problems you can possibly help diagnose why and help ensure success the next go round.

I learned a lot of info last night that explains random failures that I've seen over the last 15 years.

cool. Wanna fix the ac in my 69?

[sspstang]

(his name is robbie - eight 1 seven 437 1691 ) (and it was 30 for the condenser and hard lines)

I bought a set of pro stars off of him. He is a good guy. Is that still mansfield where he is at, or is it lilian?

[dville_gt]

I bought a set of pro stars off of him. He is a good guy. Is that still mansfield where he is at, or is it lilian?

he calls it mansfield, it's bfe either way

[shumpertdavid]

cool. Wanna fix the ac in my 69?

I'd be up to the task, however, when I delivered the Railroad electrical box to your house I believe it was a little over an hour and a half 1 way.

With the vintage air setups and other classic car a\c vendors, I would think it would be pretty easy to put a system together. I had a customer that purchased a 65 289 car. It has a sanden compressor w\adapter bracket in place of the old york techumseh. The rest of the system appeared to be stock type parts aside from the r-134-a conversion fittings. It was an underdash a\c. He hasn't asked me about servicing or checking it so I assume it's working good for him. The sanden should be a more HP and fuel friendly compressor from a lesser drag stand point and doesn't take near as much room.


As far as refrigerant charge amounts go. It's not so much about gauge readings with R-134-a. R-12 was so forgiving, if the pressures were close you most likely had cold air, the oil mixed\blended with the refrigerant to ensure it was carried through the system. R-134-A relies on the oil to be suspended in the refrigerant and carried through. It is easy for it to fall out of suspension. On an expansion valve system when the refrigerant level gets low (as little as 10% of total charge lost) then the oil will not carry all the way through the evaporator to be carried back to the compressor. Eventual result would be lack of lubrication to the compressor, heat build up, and eventual failure just like if you allowed your engine to run low. Orifice tube systems will have a similar problem in that it won't carry the oil through the evaporator core and allow it to collect in the bottom of the accumulator to allow it to weep back into the line to return back to the compressor.

As I stated before, a 3 hour class last night helped to explain a lot of failures that I've seen over the years that I chocked up to old, defective, worn out, or just plain "went bad" parts. Aside from leaks such as front seals, case joints, etc.

I've said for a long time that can filling a r-134-a vehicle is not a good way to do it. They are pretty specific on correct refrigerant charges. Pressure has a role and helping to determine charge amount, but the inlet and outlet temperatures of the evaporator core lines will get the you where you need to be.

[Baron Von Crowder]

Mine was factory a/c, and its all complete.

[KBScobravert]

I'd be up to the task, however, when I delivered the Railroad electrical box to your house I believe it was a little over an hour and a half 1 way.

With the vintage air setups and other classic car a\c vendors, I would think it would be pretty easy to put a system together. I had a customer that purchased a 65 289 car. It has a sanden compressor w\adapter bracket in place of the old york techumseh. The rest of the system appeared to be stock type parts aside from the r-134-a conversion fittings. It was an underdash a\c. He hasn't asked me about servicing or checking it so I assume it's working good for him. The sanden should be a more HP and fuel friendly compressor from a lesser drag stand point and doesn't take near as much room.


As far as refrigerant charge amounts go. It's not so much about gauge readings with R-134-a. R-12 was so forgiving, if the pressures were close you most likely had cold air, the oil mixed\blended with the refrigerant to ensure it was carried through the system. R-134-A relies on the oil to be suspended in the refrigerant and carried through. It is easy for it to fall out of suspension. On an expansion valve system when the refrigerant level gets low (as little as 10% of total charge lost) then the oil will not carry all the way through the evaporator to be carried back to the compressor. Eventual result would be lack of lubrication to the compressor, heat build up, and eventual failure just like if you allowed your engine to run low. Orifice tube systems will have a similar problem in that it won't carry the oil through the evaporator core and allow it to collect in the bottom of the accumulator to allow it to weep back into the line to return back to the compressor.

As I stated before, a 3 hour class last night helped to explain a lot of failures that I've seen over the years that I chocked up to old, defective, worn out, or just plain "went bad" parts. Aside from leaks such as front seals, case joints, etc.

I've said for a long time that can filling a r-134-a vehicle is not a good way to do it. They are pretty specific on correct refrigerant charges. Pressure has a role and helping to determine charge amount, but the inlet and outlet temperatures of the evaporator core lines will get the you where you need to be.

We may need more info on your last paragraph as I go to charge this hybrid system.

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

[shumpertdavid]

Mine was factory a/c, and its all complete.

Yours should be pretty straight forward then. All the replacement components should be r-134-a compatible, expansion valve, drier, compressor etc. If you aren't looking for a factory type restore then I'd look into the sanden conversion like I was saying. They have great service life normally and won't put near as much strain on the motor as the old style stuff. A newer style condenser will net you better efficiency also.

[shumpertdavid]

We may need more info on your last paragraph as I go to charge this hybrid system.

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

You will need a good contact probe type thermometer to do temperature based filling. The IR type thermometers WILL NOT BE ACCURATE ENOUGH. Your inlet and outlet evaporator temperatures will need to be within 5 degrees F of each other. If the evaporator outlet tube is more than 5 degrees COLDER than the inlet then the system possibly is overcharged. If the evaporator tube outlet is more than 5 degrees WARMER than the inlet then the system is possibly undercharged. More split than that and you have an undercharge. The condenser Inlet temp should be 25-30 degrees F higher than the outlet temp. More than that and it has a restriction. Less than that and you don't have enough airflow.


You need to pull a vacuum on the system at minimum for an hour, 2 would be better. 29.5" of vacuum is what it needs to pull, less than that and it won't properly boil off the moisture. The compressor needs 3-4 ounces of the correct pag oil in it. The accumulator will take the other 4-5 ounces. Total system oil capacity should be 8 ounces. The a\c system will distribute it around as it runs. If the compressor has a fill or drain plug in the body then add the oil there, otherwise pour it in the suction (large port) side of the compressor.

[dee]

Vacuum time won't matter at all unless the oil is good in the pump and not saturated.