a/c receiver drier

the911Tprocess · 09-02-2006, 06:29 AM

All,
Awhile ago I purchased a replacement receiver dryer for my early 911, thought I'd use it later. Now that I do need it, I spotted a small hole in one of the plugs that kept the drier sealed. Otherwise the receiver drier is new.

Now that it has been exposed can I resurrect it. I've heard from discussions that I could revitalize it by putting in the oven, is this possible?

Thanks any help would be appreciated.

Mark

Barrpete · 09-02-2006, 06:56 AM

The R/D contains a dessicant material that absorbs moisture from the refrigerant. If it's been open to the air, then more than likely the dessicant has absorbed moisture. You can drive the moisture out of dessicant by heating it, but I'd be leery of heating the R/D itself. I'm no expert but I'd wonder if there are any components inside it that shouldn't be heated up.

You could try using a vacuum pump to pull a vacuum on it which should also remove the moisture. You'd probably need to pull the vacuum for several hours though.

the911Tprocess · 09-02-2006, 07:00 AM

Thanks much appreciated. I will try that.
MarK

Por_sha911 · Por_sha911's Garage

I am not an expert on A/C and I didn't stay at a Holiday Inn last night but, I don't think that pulling vacuum is going to revitalize the R/D. I suggest you get a second opinion from someone like Kuehl to answer the question.

Barrpete · 09-02-2006, 07:20 AM

It may not. The hard part would be trying to figure out if it worked or not - short of installing & running the system.

The best bet may be to just buy a new one. They are available after market relatively cheaply.

ayglass · 09-02-2006, 09:20 AM

Generally, when A/C systems are serviced they pull a vacuum for 30 minutes or so and call it good. What is actually needed is about 2 hours under vacuum. The moisture evaporates quickly, but it takes a while for the dessicant to give up all the moisture it's collected. I find that in a "wet" system that's been opened (usually by the owner doing some other project and forgetting that the system shouldn't stay open) that the vacuum comes down to a certain point and that the last couple of inches of mercury are slow going. Vacuum it down, close the valve to the vacuum pump and let it sit for a half hour. If you lose vacuum over that time, then you either have a leak or your dessicant is still giving up moisture and you need to pull a vacuum on the system longer.

kuehl · kuehl's Garage

the911Tprocess,

"chances" are you will be able to use the drier even though it has been exposed to atmosphere.

"chances" would be you would not want to use it if it was submerged in water.

So what is the difference in the two opinions above? Basically the volume of water in the desicannt.

You could "revive" the unused (lacking oil) drier by raising its temperature. Its done often in products that contain drying agents however I would say the procedure is not worthy for the moment. The drier contains small desicannt balls, steel or aluminum depending upon its design (most 911 driers are steel and copper brazing), a woven cloth bag to hold the desicannt,
a piece of glass and an oring. The oring, typically behind the site glass, and the site glass may also have a plastic washer or back-up ring, is what makes the practice of moisture removal by heat a questionable procedure without knowing the properties of the oring or plastic... what temperature can you bring it to.

As far as how long of a vacuum, how deep of a vacuum and at what given ambient, you can read up on the basics at this URL below:
http://www.robinair.com/acsolutions/acvacuum/acvacuum.php

FYI: we have found a "3" hour evacuation works well on the 911 and 930, and you can help a questionable drier along in the process simply taking a heat gun or good hair drier and carefully warming up the drier toward the last hour of evacuation.

the911Tprocess · 09-03-2006, 07:55 AM

Thanks very much for all your recommendations. I've got a vacuum pump and will try the 3 hour approach. In the meantime, I will go out a buy a new receiver dryer just to ensure the least amount of moisture left in the system.

Thanks again.
Mark

Motorhead-45 · 09-03-2006, 09:15 AM

Advanced Auto Parts, Autozone and probably most of the generic parts houses sell a universal drier with the correct flare fittings. Going price is about $14.00 and is manufactured by "Ready-Aire" under part number 4104. For that price I wouldn't chance using your current drier.

kuehl · kuehl's Garage

Quote:

Originally posted by Motorhead-45
Advanced Auto Parts, Autozone and probably most of the generic parts houses sell a universal drier with the correct flare fittings. Going price is about $14.00 and is manufactured by "Ready-Aire" under part number 4104. For that price I wouldn't chance using your current drier.
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If the pic above you are suggesting Mark use in his 911, I'd think I'd rather by an aftermarket that had the proper ports (and adapters if necessary) at the right locations and the right diameter.

Motorhead-45 · 03:45 AM

Yep, I'm sure the $69.00 version from Griffiths is a much better choice.

The flare fittings on the part # I listed are correct, at least for my 1980 911. Yes the drier is slightly larger in diameter than the original drier but if I recall the original is held on with an adjustable hose clamp that takes about 15 seconds to replace if the existing one is too small and yes I had to connect the flexible hose to the top flare fitting rather than the original location on the side. I think all of that might have added a couple of minutes to my installation.

ruf-porsche · ruf-porsche's Garage

Quote:

Originally posted by Joeaksa
You can do what the can says but you are putting the gas out in a liquid form, which makes it even more important to keep the rpm's above idle, otherwise it can and will bog the system down. Have also heard that is can damage the compressor but have not seen it happen myself.

Personally I keep the can right side up until its mostly empty then invert or warm it to get the last bit out of the can.

The dryer is trying to dry things out. Leave it open and it will try to dry all the moisture out in the world, which is not going to happen and after a short time it will stop doing its job. Capping it and putting it in an airtight bag will keep it fresh. In the old days have heard of people baking a used one in the oven for a few hours to get the moisture out and then re-use it, but even as Scottish as I am, not gone that route just yet.

Joe A