Orifice tubes

[lil_Blue_Ford]

So I have done some searching but I still feel like results are inconclusive.

What I’m working on right now is my 92 Ranger with factory AC. Naturally it had R-12 originally. Don’t believe it was ever converted to R-134a since there was not the common fitting on the accumulator. Some previous owner removed the pump and cut the suction line out. I stripped out everything but the evaporator and used the good pump from my 00 with the rest new. Vacuumed it down after getting it together but haven’t filled it yet, partly because I’m not sure about if I should change the orifice tube or not. Bear with me, I did pull the orifice tube that was in there and I believe it to be brown in color. Local parts store wanted like $20 for a new one (not sure what color). I had the bright idea of ordering a variable one online that said it fits.

Thats about where things started to go off the planned course. I had everything set up and was going for it. I put the orifice tube in and the liquid line wouldn’t fit over. After some work at it I finally determined that there are little plastic nubs on the orifice tube and the ones on the variable one were in a different spot. Pretty sure it would fit if I trimmed those off, but I wasn’t sure if that might cause a potential problem. So I rummaged around in my spare parts and came up with a brand new blue one that I picked up somewhere and forgot about. It matched the size and shape of the one that came out of the truck. Not really considering that colors could mean much, it went in. Now that I discovered color does matter, I’m wondering if I need to make a change or not. One thing I read said to stay with the same color and another said that blue is the typical color for Fords that got converted from R-12.

So… what say ye?

 

[Dirtman]

So… what say ye?

Hehe you said orifice...

 

[ericbphoto]

I just did a little bit of Googling and don't have a solid answer for you. Two pdf tech articles I read on Rock Auto's site said always stay with original size. But they didn't mention whether converting from R12 to 134 makes a difference.

I also found a cool chart with the different orifice colors, OEM part numbers and orifice sizes. Brown is 0.062" and blue is 0.067" if I recall correctly.

Sorry.

 

[lil_Blue_Ford]

I just did a little bit of Googling and don't have a solid answer for you. Two pdf tech articles I read on Rock Auto's site said always stay with original size. But they didn't mention whether converting from R12 to 134 makes a difference.

I also found a cool chart with the different orifice colors, OEM part numbers and orifice sizes. Brown is 0.062" and blue is 0.067" if I recall correctly.

Sorry.

That’s kinda where I was at with it. It will be a real pain to change it now, but I would kinda rather do it right

 

[Shran]

I just went through this last fall when I rebuilt the AC on my stepside truck. I bought some kind of a kit from RockAuto that included a blue orifice tube and for the heck of it I bought a brown one too. And I see that there is a red one available..... this is the conclusion I came to:

Blue is "standard" duty
Brown is "severe" duty for really hot climates
Red is "adjustable"

I used the brown one. There was a blue one in there originally. A bunch of forum research I did suggested that either the brown one was the one to use or that the brown ones suck real bad and get clogged up, I basically wrote all that off and ignored it since there was so much conflicting info there.

FWIW my AC, although currently residing in a 1988 truck, consists of ALL the AC parts from a 1994 Explorer so it wasn't really like I converted an older system. But I think you would be fine with either blue or brown and maybe blue would be my preference in your case since PA is pretty far north.

 

[Eddo Rogue]

Much like on humans, the orifice tube is very important, and must be clean for proper function. Put in a fresh one, they're only a few bucks.

 

[RobbieD]

I think you would be fine with either blue or brown and maybe blue would be my preference

Don't do the brown acid! I found that out that at Woodstock.

But when it comes to orifices, I've used the red adjustable on a '90 B2 conversion, and wasn't impressed with it. On a '94 Explorer rebuild, originally 134a, I used the blue, trying to stay "stock" and it works OK.

 

[Shran]

Flesh colored orifices are really preferable... brown makes me frown and blue may be dyed that way from portapotty water.

 

[RonD]

An Orifice tube replaces an Expansion valve in an AC system
Expansion valves often have an external control that could be adjusted to AC needs
Orifice tube has no external control

Eithers purpose is to slowly release the high pressure R-134 into the Evaporator and the low pressure side of system, which produces the cooling effect in the Evaporator

The Orifice tube does adjust "automatically" with outside temp
But that's from the nature of the AC system, as outside temps go up, so does internal pressure in the AC system
At 70deg AC low side would be 45psi and high side 200psi
At 100deg AC low side would be 55psi and high side 320psi
The high side goes up much faster than low side
So with the higher pressure more R-134 would flow out thru Orifice tube increasing cooling in Evaporator

I would stick with the Blue for Ford AC systems

The Blue would have a larger "hole"(orifice) for the R-134 to pass thru
Brown has a smaller "hole"

The slower you release the R-134 the more cooling you get, but...................you have to watch out for Freezing, which blocks the system
Much like when you are low on R-134 you will get freezing because the low side becomes too low, so high side can expand much faster in the evaporator causing "over cooling" and the freezing

It is a balancing act, lol

 

[lil_Blue_Ford]

I just went through this last fall when I rebuilt the AC on my stepside truck. I bought some kind of a kit from RockAuto that included a blue orifice tube and for the heck of it I bought a brown one too. And I see that there is a red one available..... this is the conclusion I came to:

Blue is "standard" duty
Brown is "severe" duty for really hot climates
Red is "adjustable"

I used the brown one. There was a blue one in there originally. A bunch of forum research I did suggested that either the brown one was the one to use or that the brown ones suck real bad and get clogged up, I basically wrote all that off and ignored it since there was so much conflicting info there.

FWIW my AC, although currently residing in a 1988 truck, consists of ALL the AC parts from a 1994 Explorer so it wasn't really like I converted an older system. But I think you would be fine with either blue or brown and maybe blue would be my preference in your case since PA is pretty far north.

That makes sense and sounds like I would be ok with any of them.

 

[lil_Blue_Ford]

Much like on humans, the orifice tube is very important, and must be clean for proper function. Put in a fresh one, they're only a few bucks.

Got a new one, was just trying to figure out if I had the appropriate new one

 

[lil_Blue_Ford]

Don't do the brown acid! I found that out that at Woodstock.

But when it comes to orifices, I've used the red adjustable on a '90 B2 conversion, and wasn't impressed with it. On a '94 Explorer rebuild, originally 134a, I used the blue, trying to stay "stock" and it works OK.

Interesting. I read a number of things suggesting the adjustable ones were the way to go but that sounds like a fixed one is pretty much as good.

FWIW, the adjustable that I got was black and does not fit without modifications, so… sounds like I ended up with the wrong adjustable one.

 

[lil_Blue_Ford]

An Orifice tube replaces an Expansion valve in an AC system
Expansion valves often have an external control that could be adjusted to AC needs
Orifice tube has no external control

Eithers purpose is to slowly release the high pressure R-134 into the Evaporator and the low pressure side of system, which produces the cooling effect in the Evaporator

The Orifice tube does adjust "automatically" with outside temp
But that's from the nature of the AC system, as outside temps go up, so does internal pressure in the AC system
At 70deg AC low side would be 45psi and high side 200psi
At 100deg AC low side would be 55psi and high side 320psi
The high side goes up much faster than low side
So with the higher pressure more R-134 would flow out thru Orifice tube increasing cooling in Evaporator

I would stick with the Blue for Ford AC systems

The Blue would have a larger "hole"(orifice) for the R-134 to pass thru
Brown has a smaller "hole"

The slower you release the R-134 the more cooling you get, but...................you have to watch out for Freezing, which blocks the system
Much like when you are low on R-134 you will get freezing because the low side becomes too low, so high side can expand much faster in the evaporator causing "over cooling" and the freezing

It is a balancing act, lol

Interesting. Oddly enough the system in my F-150 will blow frost out of the vents but I know the system is borderline too full. No idea what orifice tube is in it, never had the system apart, just topped it off awhile back. I rarely use the AC in the F-150 though because it has the wing vent windows. As I was reminded today, the red Ranger has no wing vent windows and no rear slider and absolutely sucks at getting airflow through the cab to actually cool anything by just opening the windows.

 

[lil_Blue_Ford]

So I left the blue one in and got the system mostly charged. Still have to check it but I got roughly the right amount of juice in it. Blows cold-ish. Was really hoping for frosty, but I suppose it’s adequate. Probably should have changed to brown. Green Ranger will get either brown or variable I think when I get that back together.

 

[RonD]

The Brown one, with smaller hole(orifice) doesn't make it colder persay, its smaller to release compressed(high side) "freon" slower into the low side so it can expand more which does make it colder when temps outside are higher than 90deg or so

If you overfill then low side doesn't go as low so compressed "freon" can't expand as fast so less cooling
If its under-filled then it will get colder but can also freeze moisture in the incoming outside air and block the evaporator, no air flow thru it
Evaporator should be 35degF at the coldest, 40degF is normal, dropping below 32degF is when you have a problem, it becomes a "freezer" not a "refrigerator" lol

Its a balancing act betwen high side and low side pressures