failed reversing valve

I just replaced the reversing valve on an old Tempstar package unit. DAMN... the cost of the job would've half replaced the unit, but the owner sez no. So you do the work, and only warrant that part, no?
It's a pilot-operated valve.
Anyway, what I am curious is, what is the mode of failure on these valves? One assumption I could make is that one of the pilot lines - almost as small as capillary tubing - has become clogged. The armature in the pilot valve moves freely and hits both seats with authority.
If there isn't a general consensus on why these fail, I'll probably dissect it on my own time to try and figure it out.
And no, I don't want to fix it. I just want to understand why it failed. If they do fail from grod in the pilot lines, it seems to me it's just an invitation for a new valve to fail in the same way.
Ideas?
LLoyd
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On Fri, 28 Dec 2007 19:20:58 -0000, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:>I just replaced the reversing valve on an old Tempstar package unit.

Exactly why any refrigeration system needs to have someone follow proper brazing practices, driers, charging, evacuation and servicing. If it were that easy, everyone would be doing it. Bubba
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I agree... sloppy, overheated, un-purged brazing seems to be the norm in this area, and I've had to do a lot of practice on scraps to get to the point where my joints are clean enough - inside and out - to pass muster.
I gather you mean that chaff in the pilot lines IS the common failure mode?
For what it's worth, though, this is a factory-sealed system - nothing but the service ports have ever been opened. So, if soldering practice caused the failure, it was from the factory. I guess dirt from a clumsy topping-off might have caused it, too.
LLoyd
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I doubt plugged pilot lines are the problem - at least I've never found any. The pilot lines see a pressure difference equal to the difference between suction an discharge, so its tough to plug em. Given the age, I would suspect wear or debris on the main piston/slide/shuttle , gummed-up or damaged plastic or rubber on either the pilot or main or a plugged bleed hole on the pilot. As to repeat failure - these things are installed in a position so they are damn tough to just replace using all the original fittings only without damaging the valve. I typically play it safe and add a couple (or sometimes more) couplings as needed in a place that's accessible and braze the valve with 50-60% silver with the valve completely out in the open, then do the couplings with the valve installed. Also - doing this frees you from the need to use the OEM valve - the old monsters especially cost about the same as a compressor.

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wrote:

Well maybe your eye are old and you need glasses? :-)

Never say never. It'll get you everytime

Didnt you just say up top that pilots dont plug? And the op did say the piston slid freely and with authority

Yup, same way I do them but I use the valve recommended. I also braze (not solder) with the sticks, Dynaflow, Stay-silv 6 of 15 I believe its called. Bubba

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Most units make a loud noise I think they call "windmilling" when the reversing valve is changed during operation as when changing into and out of the defrost cycle. Do you think that switching under pressure could casue lots of wear to the reversing valve?? What exactly makes the noise?
Mark
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wrote:

I'll bet you have a funny name for your "member" too? I dont call it "windmilling" (...wtf?) I call it "the reversing valve switching noise". It doesnt change "into" and "out of" the defrost cycle. It does however perform a defrost cycle when needed and terminates the defrost cycle when needed. I think any reversing valve movement causes wear. Same thing as when your tires on your car roll on the pavement. When you can figure out how to stop the wear, call me. I can make you famous. Bubba
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No I don't mean just the click sound...
I hear mine and my neighbors make a 5 to 10 second very loud whoosh sound like the escape of pressure. I assume it is the refrigerant flow that happens when the reversing value changes position (for the defrost cycle) while the system is operating and there is a large pressure differential. Mark
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exactly
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OK good. so my question now is, this large pressure flow seems like it might not be so good for the valve... In other words, does this wear out the valve?
Mark
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wrote:

and I'll answer again. Of course. Any movement will cause wear. If you would like, you can disconnect the solenoid from the reversing valve. This will stop the "whoosh", the movement, the wear and the cooling operation. Bubba
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Bubba wrote:

LOL
--
Zyp



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On Dec 28, 1:20pm, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:

How you figure that? If you do the work then presumably you've diagnosed the problem. Labor should be covered for at least 30 days.

They all are, AFAIK.

Yep, forget about it. It'll work or it won't. Too late to worry about it now.
We don't typically dissect parts to see what specifically happened to them, especially not reversing valves. Taking them apart would most likely obliterate all traces of the original defect.
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them.
The pistons have flouropolymer sealing surfaces that indeed can wear / flake off.
--




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And yet....so many have lasted 30 or more years. There is a fine line between "wearing", and "wearing out". If a reversing valve fails it's more than likely due to something other than ordinary wear, not that it can't happen.
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Not all. That's why I specified the type. Some of the older low- capacity Tempstars (2-3 ton) have what I can only call a humongous changeover solenoid around a stainless steel valve body. No pilot lines at all (unless there are some internal pilot passages in the slide). But they don't change over under pressure, shutting down completely before switching.
We have an inordinate number of package units around here, what with all the mobile homes. You see some strange ones, and some very, very old ones, too. I worked on one back in April that was a HUGE northern style gas-pack. It was big enough to be a 5-ton, but only good for 2.5. I'm not a gas guy, but this was only a condensor fan motor replacement.
LLoyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

With package units fairly common to see manufacturers using the same skidpan, sheet metal shrouding, controls wiring harness, ect. across a tonnage range.
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