a/c advice requested

Have owned a '95 1.9L Merc Tracer for 6 years. Keep it well maintained. No problems. A/C, in particular, has always worked A+. Pressure right on spec. Hoses are in good shape. No leaks.
Blows cold.
Just went for regular oil and filter change at oil/lube place I have been using for 5+ yrs. (part of "Penzoil" chain). Service mgr. evaluated the a/c system the same as I did. But he still pushed very hard for me to purge system and replace refrigerant (an extra $90-$100 service). He claimed that the refrigerant "wears out" (something I have never heard before), and "that it should be replaced at least every 5 years because when it does (as he said), "it causes condensation in the system which can ruin the compressor."
Hey. Summer's coming and no one wants their a/c to crap out on a hot day. (But no one wants to be scammed out of $100, either). And I'm wondering how the hell can you get "condensation" in a system that has no water in it to begin with. (As I said, the hoses and fittings are all in good shape).
Any a/c experts out there? Does this guy know what he's talking about? Was he giving me good advice? Should I get the a/c serviced when it's working fine right now? Or was the guy just trying to put some extra commission on his next paycheck?
Looking for advice.
Jeff
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On Mon, 11 May 2009 15:05:13 -0400, snipped-for-privacy@webtv.net (jeffry gagnon) wrote:

Did you ask him where this magic condensation comes from? Is it "leaking" in from relatively low atmospheric pressure into a high pressure A/C system? The laws of physics say no. When an A/C system is serviced, just before being re-charged with refrigerant, they pull a vacuum on it to evacuate the moisture from the system. If you had moisture in the system, that's what the drier is for.
He's trying to rip you off, plain and simple. I wouldn't let the son-of-a-bitch touch my car ever again. And I'd probably report this type of activity to the local press. They love going after rip-off people like this, especially in this economy.
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Thanks Tim-- That's just about what I thought — an attempted rip-off. At this time of year they probably tell their service techs to try it on every customer, and I'll bet they get at least half of them.
Btw, it was a "VALVOLINE Instant Oil Change" that tried to scam me (not a "Penzoil", as I first said).
I'm looking at the computer-print-out receipt right now. It's got the store#, the invoice#, the date and time, the manager's name, the service tech's name, and the "recommend service A/C" box is checked.
It gets even better: There's a section at the bottom which says: "CALL 1-877-208-1171 AND TELL US ABOUT YOUR VISIT". It's connected with a "CHANCE TO WIN $500 IN GAS MONEY SWEEPSTAKES" (in order to get customers to call, I suppose). I believe I will. It'll be interesting to see how the main company handles it.
Jeff
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I have wondered about this. If they remove the water vapor from the system before the charge - why do they need the filter/dryer? My guess is that there is a way for moisture to get into the system.
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On Mon, 11 May 2009 16:30:58 -0700 (PDT), MeatmartUSA

No, sometimes they don't evacuate the system completely for long enough, which can leave a very small amount of moisture in the system. When I used to do commercial refrigeration calls with my father-in-law, on some of the big R-502 systems, we used to pull vacuums for 24-36 hours. R-12/R-134a systems aren't quite as picky.
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The only thing one might want to do at five years is add a bit of oil, unless there is a leak.
I would take the vehicle to a dealership or an AC shop, for ANY service, however.
wrote:

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On May 11, 3:05 pm, snipped-for-privacy@webtv.net (jeffry gagnon) wrote:

If it works great, the only maintenance you need to do is check the belt that runs the compressor and take a garden hose and clean the condenser that's in front of the radiator. Other than that, never go to that place again. The service manager is trying to rip you off and he's also pressuring all of his employees to rip you off also. Go to You Tube and see some of the rip-offs that Jiffy Lube has done. I would consider this shop no better.
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On May 11, 3:05 pm, snipped-for-privacy@webtv.net (jeffry gagnon) wrote:

He wants to do a wallet flush. Find an honest mechanic.
Jeff

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If your AC quits working, it will be because either the refirgerant ran away from home.... or something in the system broke...
Refrigerant doesn't wear out.... and your oil change guy has tried putting his hand in your pocket. Calling him a "Service Manager" is a lot like calling a burger flipper a "Chef".
Depending on the system, you will find a receiver/drier or a suction accumulator - either one of these will contain a dessicant. In this life, it is rare to find those things that are 100%. And this is why the dessicant is there.... to absorb any moisture that may have escaped the deep vacuum process.
The moisture... The reason we are concerned about it... in a properly functioning system, there will be plenty of the correct lubricant circulating with the refrigerant (we don't use mineral oil any more because it wont carry with R-134a).... the reason we are concerned about moisture is because of the "event horizon". An AC system has either an orofice tube or an expansion valve... it is here where the refrigerant undergoes the change in pressure that results in cooling. If moisture makes it to this point, it will freeze and block off the system....
Your Penzoil store sounds more like a pick-pocket.

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