Mother AC Problem + Orifice Tube - Ford Bronco Forum
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post #1 of 8 (permalink) Old 09-07-2018, 05:24 PM Thread Starter
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Mother AC Problem + Orifice Tube

Lets face it, most of us just dump new refrigerant into the system and hope that all the leaks are it
I dont need to make a science out of it, nor pay some guy $900 to do what I can get close to doing
So I buy a POS gage from harbor freight and it looks like I have 300 PSi on the Lo side and 150 PSI (engine running) on the high side
Not normal
Normal should be 20 on Lo side and 200-300 on high side
So I look at every You tube video out there and every Jackass out there talks about everything but this
They talk about parts Ive never even heard of 'orrifice tube' ....??

Spell it out for me if these parts are part of the compressor, say 'you need a new comporessor'

Very frustrated, auto AC vids out there are junk

'96 Bronco w/ 5.8L engine

WHERE, is the 'Orrifice Tube' physically located in the AC system ??

'96 Bronco w/ 5.8L engine

WHERE, is the 'Orrifice Tube' physically located in the AC system ??

Last edited by miesk5; 09-10-2018 at 01:28 PM.
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post #2 of 8 (permalink) Old 09-07-2018, 07:40 PM
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Are you sure the gauges are not on backwards?

1994 FSB 5.8 E.B.
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post #3 of 8 (permalink) Old 09-07-2018, 10:18 PM
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Any obstruction in your system can cause pressures to be abnormal.

Evac your system and remove your filter (also called receiver drier) and see if it is packed full of metal shavings. Next check the little orifice tube and check it for clogs. Also remove your condenser and back flush it.

Sometimes a compressor will explode and the person just replaces it. The metal shavings sit around and cause clogs.

If the system has never been flushed and the air completely boiled out with vacuum there could be lots of stuff in there.

Without a machine I guess you can clean lines and evaporator and condenser, and replace filter and tube, but then get system evacuated and filled and maybe save money.

When I switched my one truck from r12, the amount of crud in the lines was insane! Rusty shavings mixed with probably the wrong pag oil makes this nasty snot stuff.

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post #4 of 8 (permalink) Old 09-07-2018, 10:23 PM
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The point I never made was with our older trucks we never know what the previous owners did. So we often have to just start over, clean up their mess, and do it right.

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post #5 of 8 (permalink) Old 09-07-2018, 10:25 PM
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I think the low side gauge is bad. Take it back and get another gauge set.

This is assuming, it did work before and you have not worked on it.
If you have done some work, let us know what you've done.

Did you add a leak sealer? you might have plugged up the condenser or evaporator.
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post #6 of 8 (permalink) Old 09-08-2018, 10:01 AM
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Yo red011862,

See Recharge by jowens1126 @

"High pressure port is on the drivers side near the radiator, low pressure port is located on the dryer on the passenger side near the air box."
And then go to jowen1126 Rebuild @

Spend some time reading about the 96's CLIMATE CONTROL SYSTEM in 96 Bronco Workshop Manual, partial @ 1996 Bronco/F-Series Workshop Manual
A/C Refrigerant System Operation

Go to Section 12-03A: Air Conditioning System, Manual A/C-Heater
Read about the A/C Evaporator Core Orifice, etc.
Here is some info:

Item Part Number Description
1 18527 Blower Motor
2 Suction Line (Part of 19D734)
3 Discharge Line (Part of 19D734)
4 19D734 A/C Manifold and Tube
5 19703 A/C Compressor
6 High Pressure Service Valve (Part of 19972)
7 19712 A/C Condenser Core
8 19835 Condenser to Evaporator Tube
9 19930 A/C Blower Housing
10 19B735 A/C Evaporator Case Cover

The A/C evaporator case (19897) is attached to the engine side of the dash panel. It contains the:
A/C evaporator core
Suction accumulator/drier
Blower motor (18527)
Heater blower motor switch resistor (18591)
A/C damper inlet door (19C802) and its vacuum control motor (18A318)
A/C vacuum reservoir tank and bracket (19A566)
Vacuum/electrical wiring harness assemblies
The suction accumulator/drier is clamped to the A/C evaporator case with its inlet tube connected to the outlet tube. The air conditioner A/C cycling switch is installed to a fitting on the side of the suction accumulator/drier. The inlet tube to the A/C evaporator core contains the A/C evaporator core orifice tube."

"Before servicing the climate control system, perform a visual inspection of components. Check all refrigerant line connections for indications of leaks. A refrigerant leak will usually appear as an oily buildup at the point of the leak. This is caused by refrigerant escaping through the faulty connection. As the refrigerant escapes, a minimal amount of refrigerant oil escapes along with the refrigerant. Over time, this refrigerant oil collects around the refrigerant leak and will take on the appearance of a dirty/oily deposit."

"In addition to visual inspection of the refrigerant lines, the drive belts (8620) should also be examined for evidence of age and wear. Look for signs of cracks and fraying on the drive belts. Drive belt tension should also be checked. Drive belts showing signs of wear should be replaced. Refer to Section 03-05 for information on drive belt tension and replacement."

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post #7 of 8 (permalink) Old 09-08-2018, 06:01 PM
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Take it somewhere and have it checked to make sure you didn't get a set of gauges made by the newest 8 year old Taiwanese prison labor.

If they see the same high pressure on the low side your gauges saw, then start checking the rest of the system like they've shown in the prior posts.

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MY A/C Vacuum leak repair
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post #8 of 8 (permalink) Old 09-10-2018, 01:16 PM
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Yo red,
Thought I gave you info last week?


Pics by jowens1126

Orifice Installation:
Hopefully this is the best pic you will ever see to explain how to replace this I searched around and sure diagrams and written explanations but sometimes a pic just helps....
See pic at
You need the 1/2 plastic A/C / Fuel line disconnect tool.
You also need a set of long, skinny needle nose pliers. I used Harbor Freight Item#63815
I need a 3/4 wrench and 5/8 wrench for the two disconnection points closest to the accumulator for the nuts near the radiator for the condenser.
Remove the large nut suggested above with the 3/4 wrench using the 5/8 to hold onto the fixed hex nut closest to the nut you're working on for support.

Use the 1/2 A/C line separator tool and slip it ON to the metal tube going to the evaporator just BELOW the larger round section at the end of the hose that goes to the condenser.
Press up and seat the 1/2" A/C line separator tool into the condenser hose to you expand the spring lock ring. You'll feel it but spin it around once you feel you're good to make sure you're good.

Because you were smart and disconnected the condenser line near the radiator, you can now spin the hose near the evaporator and pull up. Do it with precision and finesse and it will pop out. Don't force it or you'll bend the line and hate life.

NOW you can see your orifice tube!!! If you look at an angle with a nice shiny light from above and your head isn't in the way. Yes it's kinda deep in there.

Now comes the "fun". Pour some new refrigerant oil meant for your new setup and let it sit for a few minutes. 10-15 is good.

Grab the top of the orifice tube down deep in there with the tips of the needle nose pliers. Keep them mostly compressed so you can grab that tiny lil tab on the top.

Now comes the hardest part. Do NOT F' this up.
JUST BARELY like 1/16, Twist a bit to the right then to the left. Start very gently with barely any movement. You will feel it begin to move easily and then increase then turns just a tiny lil bit more. If you exceed an 1/8 of a turn you'll probably break it and have fun extracting.
Now you feel it's reasonably loose, squeeze hard on the pliers and pull STRAIGHT up. Brace yourself and try to use both arms to pull straight up because you need the most precision and both arms will offer it even if your back hates you.
It will slip a few times and then pop out.
Roughing up the inside tips of your new pliers will help provide some traction. I used a file and cut .5 mm separate lines with 2 cuts 1 each at opposing 45 degree angles.

It will come out. Just keep trying but if you did the above it will be the easiest you'll chance you have. Have fun!

So now you have it out! Just drop the new one in exactly as you see it aligned on the pic with the long red/blue part facing the sky and the short white part facing down. Hopefully that's exactly the same orientation when you pulled it too
[IMG]1736201923_AC87BroncoACOrificeTubeReplacement.thum b.jpg.e773050fe525b02152441cf8a8baba11[/IMG]
by entity unknown

"...The inlet tube to the A/C evaporator core is fitted with an A/C evaporator core orifice to control refrigerant flow. This A/C evaporator core orifice can be removed from the inlet tube and A/C evaporator core for replacement if it becomes necessary. However, Fixed Orifice Tube Tool D80L-19990-A or equivalent is necessary to prevent breakage when removing the A/C evaporator core orifice.

The A/C evaporator core orifice is a restriction between the high and low pressure refrigerant and meters the flow of liquid refrigerant into the A/C evaporator core. The diameter of the orifice within the A/C evaporator core orifice is 1.575mm (0.062 inch). The A/C evaporator core orifice can be identified by the RED body color and white outlet tip.

The A/C evaporator core orifice is located in the evaporator core inlet tube and has filter screens on the inlet and outlet ends of the body. The filter screens act as strainers for the liquid refrigerant flowing through the opening. O-rings on the A/C evaporator core orifice prevent the high pressure liquid refrigerant from bypassing the A/C evaporator core orifice. Adjustment or repairs cannot be made to the A/C evaporator core orifice and it must be replaced as a unit.

Suction Accumulator/Drier

The suction accumulator/drier is mounted to the front side of the A/C evaporator case and attaches directly to the outlet tube.

Refrigerant enters the accumulator/drier canister through the inlet tube and the heavier, oil-laden refrigerant falls to the bottom of the canister. A small diameter aspirator tube is located close to the bottom of the canister and runs to the top of the vapor return tube. This aspirator tube is covered with a filter screen and allows a small amount of the heavier liquid refrigerant and oil mixture to re-enter the A/C manifold and tube at a controlled rate. When the heavier liquid refrigerant and oil mixture enters the compressor evaporator to compressor suction line (19867), it has a second opportunity to vaporize and circulate through the A/C compressor without causing damage to the A/C compressor due to refrigerant slugging.

A desiccant bag is mounted inside the suction accumulator/drier canister to absorb any moisture that may be in the refrigerant system.

A fitting located on the side of the canister is used to attach the A/C cycling switch. A long-travel Schrader valve stem core is installed in the fitting opening to prevent refrigerant loss when the A/C cycling switch is removed.

NOTE: Replacement of the suction accumulator/drier is not required when repairing the air conditioning system except when there is physical evidence of system contamination from a failed A/C compressor or damage to the suction accumulator/drier.

NOTE: The compressor oil may have a dark color while maintaining a normal oil viscosity. This is normal for this A/C compressor because carbon from the compressor piston rings may discolor the oil.

There is evidence of moisture in the system, such as internal corrosion of metal refrigerant lines, or the refrigerant oil is thick and dark.
When replacing the suction accumulator/drier, the procedure given here must be followed to make sure that the total oil charge in the system is correct after the new accumulator/drier is installed.

Drain the oil from the removed suction accumulator/drier into a suitable measuring container. It will be necessary to drill one or two 1/2-inch holes in the bottom of the old suction accumulator/drier, or remove the bottom to make sure that all the oil has drained out.
Add the same amount of clean new refrigerant oil plus 59 ml (2 oz.) to the suction accumulator/drier. Use only the oil specified for the specific vehicle being serviced.

A/C Cycling Switch

The A/C cycling switch is mounted on a Schrader valve fitting on the side of the suction accumulator/drier assembly. A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem as the A/C cycling switch is mounted and allows the suction pressure inside the suction accumulator/drier housing to activate the A/C cycling switch. The electrical contacts will open when the suction pressure drops to 163-175 kPa (23.5-25.5 psi). They will close, activating the A/C clutch (2884), when the suction pressure rises to 276-324 kPa (40-47 psi). Lower ambient temperatures (below approximately 1C (30F) during cold weather seasons will also prevent A/C compressor operation, because of the pressure/temperature relationship of the refrigerant in the system.

NOTE: Temperature must drop to -4C (25F) to open pressure switch contacts. Contacts open at approximately -4C (25F) decreasing and close increasing 7.2-10C (45-50F).

The electrical contacts control the electrical circuit to the A/C clutch field coil. When the contacts are closed, the A/C clutch field coil is energized and the A/C clutch is engaged to drive the A/C compressor. When the contacts are open, the A/C clutch field coil is de-energized, the A/C clutch is disengaged and the A/C compressor does not operate. The A/C cycling switch, when functioning properly, will control the pressure at a point where the plate-fin surface temperature of the A/C evaporator core will be maintained slightly above freezing which prevents icing and the blockage of airflow.

A/C Condenser Core

The A/C condenser core is attached to the radiator support in front of the radiator (8005) with two mounting brackets at the top and bottom of the A/C condenser core. The top mounting brackets attach to the rear side of the radiator support and the lower brackets attach to the front side of the radiator support.
by Ford in 1996 Bronco Workshop Manual

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Navy & DoD (retired) ... THANKS to ALL WHO SERVE!
Please Participate & VOTE in our Full-Size of the Month (F.O.T.M.) & Full-Size of the Year (F.O.T.Y.) Contests[/B] @

Last edited by miesk5; 09-10-2018 at 01:24 PM. Reason: Pic won't load
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