Hi, I have a 1994 Ford explorer XLT with 130,000 on it. This issue I am having is with the AC system R134. Before I touched the system I noticed that the AC compressor clutch was engaging and releasing with the air on, no cold air, a sign of low pressure. I purchased a refill kit from AutoZone with a gauge. I added 2 cans of Freon, one can of oil and 1 can of stop leak per instructions. The ac system worked perfect for about a week. Then I noticed the a/c compressor clutch now is not engaging at all. With the same gauge I defined that there is now 0 pressure in the system. I bought another can to test, obliviously I have a leak, and with the one can and pressure in the system the compress is still not kicking on. I tested the pressure switch and seems to be ok.


I tried to locate the leak by checking for an A/C oil stain and a local garage want 100 dollars just to look at it. I also observed that the suction and discharge assembly hose was corroded and rusted at metal fittings.Pricing all A/C items on eBay stores I figure I can get a compressor, accumulator, condenser, orifice tube, and suction and discharge hose assembly for about 370.

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Is there anything that I can salvage from the existing system or should I just replace all.
I’m desperate to get the A/C system resolved for my wife and 2 kids cannot afford a new car.

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Thanks,
Tom from MI

 

There is a decent chance the high pressure line is leaking. It is $200 plus dealer item. That is what I had to have replaced this summer on my '94.

 

Jwireth,

Thanks for the reply. Is the high pressure line comming from the left side of the condenser? If so where does it connect to? I located it however could not trace where it connects to.

Thanks,
Tom

 

If you have no visible oil signs, most likely the evaporator coil (dash unit) is leaking. I am surprised your 94 lasted this long as my 91 is on it's third now.
But this would be a good time for total rebuild. Minimum is the evap coil, accumulator, and orifice tube, plus some flush for the lines. It would also be a good time to replace any hoses showing signs of seperation or balooning in the flex sections, and all "O" rings in the system connections. Local A/C shop replaced my flex sections at less than 1/2 new compressor manifild assembly cost.
Easiest way to get to the evap coil is to remove the entire plastic duct assembly from the firewall. It is held on by 4-5 nuts (one is hidden directly under the fan area). Once removed, the coil section can be opened and coil easily replaced. You will need to remove blower fan assembly, air filter box and some misc items for access, but not too hard of a job. You will need a good 1/4 socket set, long extension helps, and a flex joint, and some spring lock connector tools. Plan on spending several hours to do it all right.
Dialtone

 

Dialtone thanks for the reply
Where is the Orifice tube located on the 1994 explorer. I'd like to check it for black death.

Thanks, Tom

 

Dialtone

You bring up a interesting point about the evaporator coil. the week that I had the system working one thing that I noticed is that when I had the AC on and would turn the car off. I could hear a hissing sound like pressurized air escaping. This would last 3-5 seconds once I would turn the car off. It sounded like it was coming from inside the car, do you think that this hissing could be a leak in the evaporator.

Thanks,
Tom

 

The hissing you described is normal. It is the sound of the gas in the system equalizing pressure across the orifice tube when system is shut off. The orifice pipe is about the size of a pencil lead, and makes a restriction in the gas flow of the system, creating a pressure differential that allows the refrigerant to flash over from a liquid to a gas and cool off as it enters the evaperator coil.
The orifice on my 91 is in the evap lower tube where it connects to the line running from the condensing coil in front of the radiator. Should be a screw type fitting that sets below the air intake filter box, and MAY be difficult to crack if it is somewhat corroded. Orifice is slipped inside the tube to the evap coil and will be snug. Most of the time, it is impossible to remove without destroying it as it is fragile, and the pressure tends to "jam" it hard into the line, especially if the screen is plugged with debris.
About the only sure way to tell where a leak is without a visual inspection, involves using a Halogen sniffer box to detect the referigerant. A hole is drilled into the evap housing, and the sniffer probe is inserted. If freon is present, it willl register. Generally, when the evap coil is removed, it is real evident it has been leaking as it will have the telltale oil spot with some accumulation of dirt trapped in the oil.
Dialtone

 

Dialtone.

The hose that goes from the condenser to the evaporator which houses the orfice tube. I believe it is called the liquid line. I visually inspected it and it seems to be very rusty. Did you replace this line when you replaced the orfice tube? If not should I replace?

Tom

 

Whether to replace your line section(s) or not depends on the amount and type of the corrosion present. Some surface rust is to be expected, but a deeper flaking crust may indicate the line is being weakened and will eventually fail (depending on the thickness of the metal). Mine had only surface rust, so I have not replaced it or the accompanying flex section. The real test will be when you try to break the screw on connection. If it twists the pipe before it gives, cut the (evaporator) piping with a small tubing cutter (assuming you will replace the evap coil) and replace other piping as needed. Orifice tube is in a swelled out section of the evaporator side of the tubing which is aluminum and easier to cut. I cut mine to aid in removal before I tried to unscrew the connection. It was much easier to get at to work on with some of the junk out of the way first
Dialtone

 

Dialtone,

Thanks for you support. Last night I took the manifold suction and discharge hose assembly off to pressure test, which I suspected was the problem and it checks out ok. In doing so I noticed the O-rings flattened at the fittings. 2 questions.

1. Is there a A/C O-ring kit for 1994 Explorer.
2. Should there be a O-ring between the hose manifold and the 2 compressor ports, where the manifold mates the compressor? There was not.

Tom

 

I believe the high presssure line is on the drivers side but I have not looked closely at it. I think it runs most the length of the engine (front to back). I rode the Harley today so can't run out and look.

 

The old O rings will appear flattened somewhat on the mating surfaces and that is normal since they are disigned to seal against the contact surfaces.
You may find a vehicle specific kit of O rings at an A/C shop or auto parts store, but I find it is much easier just to purchase a kit of various O ring sizes from an auto supply. I always need one or two here and there (faucets, hot tub jets, ect), so having some extras around is handy. Just be sure the kit is approved for the oils it will seal against. I think the newer A/C rated ones are green in color but may also be black.
There should have been 2 O rings at the point the hose manifold attaches to the compressor. It would have been impossible to seal this connection without them. Possibly they fell out without you noticing when you disconnected it, as they fit loosely in a grooved out area of the manifold assembly, and are compressed when the bolt is tightened down.
Dialtone

 

1994 explorer
Here is a list of O-ring locations that I now of replacing Please let me know if im missing something. Not including O-ring locater internally of the suction and discharge hose assembly

2 on the back of compressor
2 on spring clamp of the hose assembly which connects to the condenser
2 on the spring clamp of the hose assembly which connects to the accumulator.

Possible.
from condenser to evaporator
and evaporator to dryer.

Your help is appreciated.

Its starting to sound like my evaporator is the issue. I’m going to try to access it tonight. I still want to replace all of the O-rings in the system. I ended up buying a ford o-ring kit.

Tom