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.