Make: Lincoln Towncar
Engine Size: 4.6L
I just replaced the condenser on the Lincoln. The service manual recommends changing the accumulator/drier as well. I've noticed this recommendation in other literature/articles as well. I was wondering what the reasons for replacing the accumulator and drier are when replacing the condenser or other major a/c components ( compressor, evaporator, metering device(s) ).
Thanks for nay comments.
It's recommended that the accumulator/Drier be changed when the system has been open for any length of time. Especially one with many years of use on it already!
Accumulator or receiver/drier typically has some form of "dessicant" in it to absorb moisture from the system. Once it's saturated, you typically need to replace the dessicant. However, on most units, the dessicant cannot be replaced separate from the accumulator/drier, so you end up replacing the "assembly".
By opening up the system for a "major repair" implies that the accumulator/drier will be open the air, and thus collect it's moisture. So you say you'll cap it while it's out? Well, if it's a few years old, the dessicant may or may not already be saturated (or close to it). Hence the firm recommendation to replace the accumulator/drier any time the system is opened for a major repair.
It's kind of like changing your oil filter every time you change your engine oil. It may not be clogged yet, but there's no easy way to tell, so best to replace it as good practice.
Edited: Wed August 06, 2008 at 2:13 PM by webbch
Thanks for the comments. They are greatly appreciated.
Sounds like the main reason for replacing the combination (?) accumulator/drier like my Lincoln has is due to the possibility of the desiccant in the drier becoming saturated with moisture when the system is opened for replace of a major component. Is it possible to do a deep vacuum and get the moisture out of the desiccant, and possibly avoid replacing the accumulator/drier. I often get interested in the technical details/aspects of some of the logic behind recommendations for doing things. I'm not arguing whether or not to follow recommendations, just curious as to the logic behind them.
Also, if changing to R134a (you didn't say) then it's even more important to change the accumulator. (not to mention oil) But on a 91, even if using R12, I would suggest changing it now..It's served it's time...
Freedoms just another word for nothing left to lose
in conjunctions with chick's reply - i would also consider changing the orifice tube . reasons - first it will give you an indication on what condition your compressor is in i.e. if there is a lot of metal in it you compressor may and i repeat may need to be changed in the near future. two - if the orifice tube is partially clogged a new one will give you better efficiency and generally they only cost about 2 bucks. good luck
I have no idea if you could try to boil off the moisture in the dessicant - never heard of anyone trying. It would be a somewhat interesting experiment if you can find some dessicant used for these systems, and put it in a container with a lid that has an r134a coupler to pull a vacuum. Weigh it with a highly accurate scale. Then leave it sit out for a couple weeks and re-measure the weight. Then pull a vacuum to see if the moisture will boil off and re-measure the weight. I'm not sure if you could control the weights accurately enough to have a measurably significant difference or not though.
The more dessicant you can obtain to play with, the better your chances of coming to a reasonable conclusion.
There is a molecular bond that must be broken. It will usually take some sustained high heat such as 200-250C.
So, your vacuum pump is not going to boil moisture off the dessicant material and it needs to be replaced.
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