What is the lifespan of a receiver-drier? - PeachParts Mercedes-Benz Forum

shertex · #1 11-03-2011, 09:41 AM

Does a receiver-drier have a typical lifespan, after which it can no longer effectively remove moisture from the AC system? If so, what is it? If I'm understanding correctly the way these things work, it seems like they ought to be replaced periodically even if the AC system is not opened up.

Thanks.

tangofox007 · #2 11-03-2011, 09:59 AM

Quote:

Originally Posted by shertex

If I'm understanding correctly the way these things work, it seems like they ought to be replaced periodically even if the AC system is not opened up.

What is the rationale behind that notion?

shertex · #3 11-03-2011, 10:03 AM

Quote:

Originally Posted by tangofox007

What is the rationale behind that notion?

My thought was that the desiccant material that's used to absorb the moisture would eventually reach capacity. Is this incorrect?

shertex · #4 11-03-2011, 10:16 AM

From one AC site I was reading:

It's important to remember that one of the main functions of the accumulator or drier is to absorb moisture from the A/C system. Therefore they include a desiccant material. Desiccants are typically made from silica gel, and because of their affinity for water, they make great drying agents. Additionally, accumulators and driers have filter screens to trap any debris. After a compressor failure, these filter screens can easily get plugged with debris. KEEP IN MIND.. some of the components that flow refrigerant through the system work with openings of less than .050" (fifty thousandths of an inch). It takes LESS THAN 1/10 of A TEASPOON OF DEBRIS to plug these components and cause a failure.

SERVICE Required: Typically, the desiccants have been proven to become saturated after three to four years of service. Once saturated, they can no longer absorb moisture. Additionally, there is no way to check the filter screens for contamination. It is very common for the debris from the compressor failure to contaminate driers because the debris is carried throughout the system. Therefore, as a standard practice, accumulators or receiver driers should be replaced whenever you are replacing the A/C compressor. Consider that it's much the same as an oil filter on you engine. You change the oil; you change the oil filter. Like any filter, there is a 'fixed' capacity for how much debris and contamination any filter can hold. Additionally, if the accumulator or drier is not replaced, you are probably going to 'void' your compressor warranty.

Is this information accurate?

Air&Road · #5 11-03-2011, 10:19 AM

This is sort of a "how long is a rope?" type question. The life varies GREATLY depending upon: how often the system has been opened, how well it was evacuated each time, has it had any low side leaks?

The dessicate will saturate ONLY if moisture has been introduced to the system. As long as the system doesn't leak, no more moisture will enter the system to be captured by the dessicate.

Replacing the filter drier as a PM item IMHO is a BAD idea. Each time you open the system, you risk contamination, introduction of moisture and the possibility of not getting the system pumped down thoroughly. Additional risk is not reintroducing the amount of oil that was removed with the r/d.

The time to replace a filter drier is when the system is opened for ANOTHER reason. Unless the system has gone through a few leak down cycles, opening the system to repace the r/d introduces more risk than potential reward. If it saturates in 3 or 4 years of normal use, where is the moisture coming from that is captured?

It will be interesting and valuable to hear VSTechs experience and response.

leathermang · #6 11-03-2011, 12:00 PM

Our systems are not hermetically sealed. This is why VStech has agreed with others like me that using a vacuum to check for leaks is not dependable procedure.

( pressure testing with 4 oz R22 and dry nitrogen and a sniffer is the recommended and EPA approved method )....

The seal at the front shaft of the compressor has a designed leak in order to keep it lubed... that is why one should start their AC system at least once per month EVEN IN THE WINTER.

Moisture control in our AC systems is extremely important... which is why I cringe when I hear people relating that they or their shop ' vacuumed for an hour ' and filled in the refrigerant.... What is the rush after all the care has been applied to get the system to work right that would ignore the fact that moisture is slow to leave the system ?

IF ONE were concerned with the potential for a normally sealed and serviced system drier becoming saturated... there are INLINE sight gauges which could be installed with pink/blue indicators to alert to the deterioration of the system integrity.

vstech · #7 11-03-2011, 03:30 PM

I'd certainly not recommend a good running a/c system have the receiver dryer replaced just because... however, IF there are leaks or if the system is ever found empty needing a recharge, I'd recommend a leak search and repair, THEN a new dryer. and of course anytime any component in the refrigerant system is replaced, a new dryer should be installed. as mentioned, mobile a/c systems are not hermetic, so they do accumulate moisture over the years. but if the system is cooling well, and has not needed refrigerant added, then no, I'd not change the dryer.

Air&Road · #8 11-03-2011, 03:36 PM

That's the kind of wisdom I expected to hear from VS. Back in the late seventies I was a Field Engineer taking care of some Bio Medical instruments that had refrigeration systems including Liquid Scintillation Counters and centrifuges. I saw a number of them that once opened for any reason, they went down quick after that requiring MAJOR attention.

Since that time, I don't even like to hook up gauges unless the system is INDEED suspect. Doing it as a preventive maintenance procedure IMHO is a bad plan.