Automotive Air Conditioning Information Forum

I'm curious if having various hose sizes will cause problems when updating an old car AC system. I'm replacing the condenser in this phase.

My old system was like this:

Hi Side: Compressor Size 10 with barb and # 10 hose clamped --- downsize adapter near condenser to short piece of hose - Size 8 hose clamped at condenser.

Low side: Drier has a Size 6 O-ring crimped fitting (the special 15 degree bend) with Size 8 hose clamped to condenser.

New Condenser of course has Size 8 for Hi Side and Size 6 for low side. Will the following scenario cause a problem?

Hi Side: Keep Size 10 hose connected to compressor and use special fitting at condenser to use 10 hose with the new Size 8 condenser connector?

Low side: Keep Old Drier fitting and Size 8 hose and use an off the shelf step-up female fitting to use the Size 8 hose on the Size 6 new condenser fitting? Second option here is to cut apart the old drier fitting and modify it with a Size 6 fitting and run 6 hose to new condenser size 6 connector.

Your thoughts on the new scenario?

I personally am having some trouble with the way you are describing, esp what to what

The typical hose sizes are as follows
evap to comp 10
comp to cond 8
cond to FD 6
FD to TXV 6

What kind of mongrel setup do you have? What is the car?
Sounds like the drier you are using has non-standard connections?
Why not just get a modern standard universal drier which is 6 in and 6 out

You could go larger than the sizes above, but never smaller

tbirdtbird wrote: ↑Wed Sep 15, 2021 1:43 pm I personally am having some trouble with the way you are describing, esp what to what

The typical hose sizes are as follows
evap to comp 10
comp to cond 8
cond to FD 6
FD to TXV 6

What kind of mongrel setup do you have? What is the car?
Sounds like the drier you are using has non-standard connections?
Why not just get a modern standard universal drier which is 6 in and 6 out

You could go larger than the sizes above, but never smaller

Sorry I'm not describing my situation well. I'm only talking about Cond to Drier and Cond to Comp. I'm not doing anything on the other side.

First: My Drier is standard universal - but the old hose is 8 even though the connector on the Drier is 6. So I've been running 8 hose from the Drier to the Cond even though the drier fitting is actually for a 6 (but crimped to 8 hose). I can stay with the 8 from Drier to new Cond and put an adapter there, so I can use the 6 connector on low side of Cond. Or cut the end off the special drier connector and put on a new connector and use 6 hose all the way to the cond (much more work cutting and silver-soldering and $$).

Next: Both sides of my comp are 10 !! Honest! This is an old Camaro. I have had 10 hose running to the old condenser. But the old condenser had a 8 port, so there was a step-down just next to the condenser. These were all clamped connections. The new cond has a 8 connector, so if I keep the 10 hose I'll still go through a transition to 8 in order to connect to cond. But I could get serious and cut into comp tube and convert it to a 8 fitting and run 8 hose from comp to cond and not need any transitions. Mechanically, I'll have to figure out which conversion is best -- but in the meantime I'm curious if any of these hose-size changes will cause any operational problems in the AC system.

So
cond to FD is now 8 and only needs to be 6, so again, you can go up in size, never down
Same for the comp to cond, you are 10 now, which is larger than it needs to be, so no problem.
Are all your connections Male Insert O Ring? Or are there flares involved

Where are you finding these adapters?

That side of the system is very forgiving, the sizes tbird listed are pretty standard. I don't think I've ever seen a #10 discharge hose, nothing wrong with it as long as it doesn't burst, only downside is it's stiffer, bigger, more expensive, harder to route, no performance problems. #8 is usually optimum, easy to route, cheaper than #10, pressure drop in this hose makes very little difference to performance.

Liquid line (condenser to receiver) is even more forgiving, you can go all the way down to a 4mm ID aluminum pipe. Bigger hoses and pipes are just more durable, almost always way oversized for the actual massflow of liquid refrigerant.

The suction side is where pipes and fittings can help or hurt or performance, discharge and liquid lines just don't matter much.

tbirdtbird wrote: ↑Wed Sep 15, 2021 4:47 pm So
cond to FD is now 8 and only needs to be 6, so again, you can go up in size, never down
Same for the comp to cond, you are 10 now, which is larger than it needs to be, so no problem.
Are all your connections Male Insert O Ring? Or are there flares involved

Where are you finding these adapters?

Right now the only O-Ring connectors are (a) Males on the new cond and (b) Female on the universal FD. If I continue to use #8 hose on the FD, I can use this adapter to make the #8 hose fit to a #6 Female and then to the #6 Male on the cond. These guys as well as Vintage Air and a few others have various adapters for stepping up or down.
https://nostalgicac.com/fittings-hose-k ... tting.html

For the FD the more complicated move is to convert the male O-ring fitting on the FD to accept #6 hose then run 6 hose to the 6 O-Ring connector on Cond.

On the Comp side of the cond (top of the cond) I am having to fabricate a 90 degree drop tube since both hoses must connect near the bottom of the cond due to clearance problems (hideaway headlights) near the top of the cond. My local guy can make a tube that has a Female #8 O-Ring to connect to the cond - then turn 90 and drop down 9 inches and another 90 out toward the hose -- and he can put a #10 Male on the end of that tube so my #10 hose can connect with a F O-Ring. There will still be a barb connection with clamp on the #10 comp tube.

For the Comp the more complicated move is to cut the #10 barb at the comp tube and solder in a #8 O-Ring fitting so I could then run #8 hose all the way to the cond (but still have the 90 degree situation drop tube with a #8 male). The smaller hose definitely easier to route.

DetroitAC wrote: ↑Wed Sep 15, 2021 5:50 pm That side of the system is very forgiving, the sizes tbird listed are pretty standard. I don't think I've ever seen a #10 discharge hose, nothing wrong with it as long as it doesn't burst, only downside is it's stiffer, bigger, more expensive, harder to route, no performance problems. #8 is usually optimum, easy to route, cheaper than #10, pressure drop in this hose makes very little difference to performance.

Liquid line (condenser to receiver) is even more forgiving, you can go all the way down to a 4mm ID aluminum pipe. Bigger hoses and pipes are just more durable, almost always way oversized for the actual massflow of liquid refrigerant.

The suction side is where pipes and fittings can help or hurt or performance, discharge and liquid lines just don't matter much.

Thanks for this great info !! I have seen the standard and the thinner #8 and #10 hose. The thinner has the same burst specs but I'm wondering if it's still best to use the double-fiber thicker hose.

Also -- When I have my drop tube made as I described above on the Gas/Vapor input side, what size tube should I use?? Would 6mm ID be best for this tube?

I don't understand what you are talking about. May I suggest we talk about the pipe/hose assemblies like this:

Discharge Line - Goes from compressor to the condenser, high pressure, high temperature gas
Liquid Line - Goes from the condenser to the receiver, also might apply to another line that goes from the receiver to the TXV/OT, High pressure liquid
Suction Line - Goes from the evaporator to the accumulator, or evaporator to the compressor, or accumulator to the compressor

I don't know what drop tube you are referring to, there is no gas only hose that could be 6mm, that's too small

DetroitAC wrote: ↑Thu Sep 16, 2021 7:21 am I don't understand what you are talking about. May I suggest we talk about the pipe/hose assemblies like this:

Discharge Line - Goes from compressor to the condenser, high pressure, high temperature gas
Liquid Line - Goes from the condenser to the receiver, also might apply to another line that goes from the receiver to the TXV/OT, High pressure liquid
Suction Line - Goes from the evaporator to the accumulator, or evaporator to the compressor, or accumulator to the compressor

I don't know what drop tube you are referring to, there is no gas only hose that could be 6mm, that's too small

On my discharge line I will not be able to directly connect my hose to the #8 fitting on the condenser because of the physical location of the fitting. The fitting is near the top of the condenser and both of my lines approach the condenser near the bottom. Looking at the condenser, I will need a 90 degree turn to take the gas from the lower left UP to the input of the condenser. Then I will need another 90 degree turn to actually connect to the #8 fitting on the condenser. Instead of using hose for this 9 inch section for the two 90 degree turns, can I use an aluminum tube for that?? Kinda like a large S. My local guy can make a tube like that but I don't know if that is smart on the Discharge side for proper AC functioning. I have seen these tubes on the Liquid side. But if I need to stick with hose all the way on the Discharge line I can do that with two 90 degree fittings.

Second part of the question: I've seen the #8 hoses with same ID but with two different ODs -- standard and thin -- should I stay with standard?

Thanks for the help! I'm not explaining myself well but hope the tube thing makes sense now.

The discharge line from comp to cond needs to be the standard equivalent of a #8 hose.
Reduced OD hose is OK but requires special fittings.
Aluminum tube is OK but you need to check the pressure rating of the tubing you want to use. The high side can sometimes (inadvertantly) get to 300-350 psi, I would want a rating of 500 psi for safety

Remember that Cold Hose in Ocala can make special fittings/tubes

Also remember that the more 90s you have that the flow will be reduced, and potentially reduce your cooling. Perhaps not enough to notice, but just be aware

I understand the need for the drop, but why does this have to be tube?