Rusted out receiver/drier

2005 Mercury Grand Marquis, 100K miles

I noticed within the last couple months that the car’s air conditioning has taken longer and longer to get cold. Eventually it stopped cooling altogether, and when I watched the compressor for operation, the clutch would only engage for at most one second at a time, and would not engage again for almost ten seconds. Seeming like a symptom of low refrigerant, I checked under the car for any neon green leakage indicating a refrigerant leak and sure enough, I saw bright green droplets hanging off the bottom of the receiver/drier. On this car it’s mounted down low in front of the engine bolted to a frame rail in a thick plastic casing. I separated the casing halves to inspect the unit directly and found that it’s rusting away pretty badly in numerous spots. There was also more bright green dye evident within the plastic casing. It’s clear that the receiver/drier will need to be replaced.

Is there anything else that should be done at the same time? I consulted a friend of mine who’s an HVAC professional and he’s said that I might as well do all of the hoses and condenser at the same time. If I’d had a compressor failure I might see the wisdom in that, but it seems extreme. Is an acceptable repair in this case simply an evacuation of refrigerant, replacement of the decaying part, and a recharge/leak test? I would be letting a shop handle the job as I don’t have the necessary equipment to fix A/C systems the right way. I’m sure I could wing it if I had to, but I’d rather not.

Thanks for your input.

The problem here is, you don’t know how much oil was lost from the system from the leaking drier.

But I don’t think the entire system requires a complete rebuild because the drier was under positive pressure. So no debris was allowed to enter the system.

What I would do in this case is, get a new drier, flush all the components in the system, make sure the compressor has the proper amount of oil, add the proper amount of oil to each component, install new O-rings to the components, pull a vacuum on the system, and then recharge it with refrigerant.


I would be concerned about the receiver/dryer having rusted from the inside out. If the desicant got saturated with moisture, the moisture would start forming acids that would attack the metal of the A/C system. The most critical being the evaporator, compressor, and condensor. I would not be worrying about the hoses as moisture and acids do not attack them as readily.

At the least, I would replace the receiver/dryer; change the compressor oil; check or replace the screen ahead of the expansion device; pull a vacuum for a long time on the warm system; check for leaks; load the requisite mass of freon; and see what develops. Maybe at the next A/C service change the receiver/dryer again.

Meh, I wouldn’t worry much about it. The accumulator, as they’re called when they are in the low side of the system, “sweats” quite a bit as it’s full of cold refrigerant. Normally the water just flows off but since Ford had decided to insulate it to be more efficient it actually sits in water inside that insulating casing. After a while they just start to corrode and leak. I see this regularly on Ford products. I see it on my own 2002 Explorer.

I can think of no valid reason to replace the hoses and condenser on the car if the system functions well at a full charge.

That was my thinking. The system functioned perfectly before the most recent winter, so I can’t believe there’s any need to replace all that extra stuff.

Like Tester said though, it’s possible some PAG oil was lost from the accumulator so accurately measuring how much is in it (and thus how much to add to the new one) might involve a bit of guesswork. Every manual and diagram I’ve read says to add however much was drained from the old part plus two ounces…perhaps I’ll make it plus three ounces. Good or bad idea? Or maybe someone has a general idea of how much PAG oil is supposed to be in an accumulator?

I’ll mention something that nobody else has . . .

Replace the orifice tube as part of the repair

You can’t think of the amount of oil that’s added to the drier is the only amount that leaked out.

The oil in an AC system mixes with the refrigerant as it moves thru the system.

This is what prevents hoses and O-rings from deteriorating.

So if the oil in the entire system gets low enough, the oil in the compressor will start mixing with the refrigerant. And this drop in oil in the compressor can damage the compressor.

That’s why the system needs to be flushed to remove the oil from the components, and then refilled with the proper ounces of oil. And the compressor drained and refilled with proper ounces of oil.

Now the system has the exact oil capacity.