Orfice tube size and color? | Ford Explorer Forums - Serious Explorations

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Orfice tube size and color?

D M Dickson

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Joined
May 20, 2007
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City, State
N. Charleston South Carolina
Year, Model & Trim Level
91 Explorer 2 WD
When converting an R-12 system to a 134A it appears that different size and colors of the orfice tube are available, what seems to work the best for a conversion on a stock 91' Exp? Thx for any help.
 



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What color orifice tube to use on a FORD?

http://autoacrepairs.com/ford_orifice_tube_application9202.htm


GM White .072 Orifice, Single black o-ring

Ford Blue or Black .067 Orifice, 2 Green o-rings

Ford Green .052 Orifice, 2 Green o-rings

Ford Red .062 Orifice, 2 Green o-rings

Ford Orange .057 Orifice, 2 Green o-rings

GM, Opel & Volvo Black/White or Red/White .072 Orifice, Single black o-ring

Ford Brown .047 Orifice, 2 Green o-rings

Chrysler, Jeep, Eagle & Dodge Purple .062 Orifice, 2 Green o-rings

GM, Volvo & Opel Yellow/White .062 Orifice, Single black o-ring

GM Yellow/White or Red/White .062 Orifice, Single black o-ring

GM, Geo & Opel Orange/White .057 Single blacl o-ring T-Tab

Audi & VW Gray/White .072 Orifice, Single black or purple o-ring

GM Yellow/White .062 Orifice, Single black o-ring no tabs

Ford Black/White .072 Orifice 2 Black o-rings

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Ford Conversion Notes:

My '94 Explorer (w/ factory R-134a) used a blue orifice tube. I’ve heard that previous years (R-12 systems), used a red orifice tube. Normally......I figure, IF the factory system worked well w/ whatever colored tube......then, I should replace the tube w/ a like colored tube. Thinking - that the orifice color, indicates a certain sized hole. But, in this case (R-12 to R-134a conversion) a switch from red to blue orifice tube might be the correct choice.

Also, check that the low pressure switch is the correct one for your application. NAPA lists different part numbers for an R-12 vs. R-134a system (remember to also check the elec. connectors).

Shamaal said:
The switch on the accumulator controls the clutch on the compressor. When the system pressure is less than 24.5 psi the clutch is disengaged. When the pressure is greater than 43.5 psi the compressor clutch engages.

And, as a COMPARISON ONLY.......the Haynes book says ('94 Ford Explorer w/factory R-134a system)........at ambient air temp of 80 degrees F, hi velocity shop fan in front of the condenser at it‘s highest speed, engine on at 1500 RPM, windows up, doors closed, AC set at Max, fan speed at it‘s highest (I‘ve found a lower speed will give a colder reading), thermometer in center vent.........you’re looking for ………22-50 low side and 160-250 high side pressure. Capacities: oil 7 oz and R-134a 2.25 lbs (36 oz).**Conversion capacities will differ, for a R-134a conversion, I've heard figures anywhere from 60-90% of the R-12 charge was good. ** Check your temps against this chart…..

http://www.autoacforum.com/aacf/ptchart.cfm


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Aloha, Mark

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AND.........


Now, I'm not an pro. Here is my thinking.......the 1st Gen with R-12 refrigerant used a red orifice tube.....my '94 with Factory R-134a uses a blue orifice tube.......so, does that mean that in any 1st Gen w/ R-134a, a blue orifice tube should be used?

POSSIBLY......remember I did say, "might."

I don't KNOW for sure.......IF, the '91-'93's systems are EXACTLY the same as the '94's system, except for the refrigerant used. In the '94 Explorer, the construction of the: condenser or evaporator or accumulator (not to mention capacity) could have been different (because of the fact that R-134a is used and not R-12). But, I also mentioned to change the low pressure switch.......NAPA, DOES SHOW different ones for the refrigerant used (R-12 vs. R-134a). Folks have also mentioned the heater manifold (in '94 a heater cut out was added), there have been different reports as to it's effectiveness (on a conversion system).

So......all together, will this be the ultimate set up, for a conversion 1st Gen AC system? Well, I don't have the PROOF........you could experiment, red vs. blue.......and report back......but, that experiment will cost you refrigerant. The FINAL decision is YOURS.

Humm......but the 2nd Gen vehicles uses a red one. Did the AC system change, again?

Aloha, Mark

PS......The accumulator needs to be correct for R-134a........I've heard that the desiccant might be different between a system built for R-12 vs. R-134a.........though, lately things may have changed.........either way.......BEST TO CHECK.

Lastly.......the system capacity for R-12 will differ from that of a system using R-134a......so, to get the BEST RESULTS, keep a close eye on the pressure gauges and temps. Record the final readings and put that conversion sticker on.........for the sake of the next guy.

And Notes About the Re-Charge...........
Remember I'm NOT a pro.......so, assume: There are NO LEAKS, the AC compressor & clutch, radiator fan & clutch, are up to the job and the system has been evacuated........

When you're re-charging the system......to start, charge it (into the vacuum) with whatever it'll take w/ engine “off.”

Then, set up a high velocity shop fan in front of the condenser and let her rip (highest speed). Turn on the engine, running at 1500 RPM, set the AC (max), *blower fan speed set at highest speed, doors closed and windows up, 10 mins. running to stabilize the system. *I have noticed that a lower blower fan speed, will get you lower temps. And, the HAYNES book says, blower fan speed at lowest speed, for the "Final Performance Test."

Continue to fill the system (w/ R-134a) to 60% of the R-12 charge. Sometimes, to help get the 60% in there, you might need to use a jumper at the low pressure switch connector, to get the compressor working. Once you get the 60% in the system, remove the jumper, reconnect the low pressure switch and observe that the clutch is working. IF the clutch doesn't energize, you may need to add a little more refrigerant (or the low pressure switch may be broken). IF you see that the compressor clutch is working. Check the ambient air temp and compare it w/ the vent temp. At an ambient air temp of 75-80 degrees F, you're looking for a 35-45 degrees F at the vent (about a 40 degree F difference, though close enough is good to). If you don't get the temps you want.....continue to add refrigerant (in the past, anywhere from 60-90% of the R-12 charge was reported to be good).......mindful that too much is no good and too little is no good......so, watch the pressure and temp readings.

Ambient air temps are taken 2” in front of the condenser. Vent temp is taken at the dash vent closest to the evaporator (usually one of the center vents).

Note the total charge and pressure readings, for future reference.

Aloha, Mark

PS......don't forget to label the system w/ a R-134a sticker.......so the next guy will know. And, IF the system still runs a little hot......you may have to go to an additional elec. fan in front of the condenser or a larger high-efficiency condenser.

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Aloha, Mark
 






Thx for the graphs and info, the blue orfice tube may be the way to go for the 134, i'll give it a try and find out how it works.
 






I just did an R-12 to R-134 conversion on my '93. I went from a red orifice tube to a blue one. The results are very good. The outlet airtemperature is in the high 30 to low 40 degree range.
 






Aren’t they different colors merely to represent the actual climate temperature range perimeters for the automobile’s permanent place of most use or point of destination? Between ( X low to Z high ) temp range as in, the blue is colder part of states, and red represents warmer? Similar to the thermostats installed when the car is manufactured will not be distributed the same for every car, but rather different depending on the part of the globe it is going to be used most.
 






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