Measuring A/C Temp Solved, sort of...

[Boris]

Stormin Mormon wrote in news:fbHbx.66737$ [e-mail]:

Yes, I've gotten my terminology mixed up. Just like learning how to maintain the pool equipment from knowing nothing about it at first, to being able to take care of it myself, between this ng, talking with service techs, and going online, I've learned a lot about proper a/c terminology and how it all works.

All along, I thought the cooling took place in the outside unit. Wrong. I didn't know there was a thing called an evaporator in the furnace...a split system. I though that if I took the fan off of the top of the a/c unit, I'd see a whole bunch of complicated stuff about which I'd know nothing. Now I see that all that's in there (besides the electronics, which are physically isolated from the inards) is a compressor (big tin can in the middle) sitting on some rubber vibration isolation bumpers, surrounded by a radiator-like set of cooling fins.

I was incorrectly using compressor and condensor interchangeably.

The theory we're working on now is that the condensor is too dirty to cool the returning hot air generated at the evaporator. Yes?

If that's not it, I would suspect the evaporator. I'll have to see if I can get at the evaporator, and if so, I'll clean it, too, and reseal.

While the tech didn't record all the data on the work order, as he checked items, he'd tell me this is in range, that is in range. He did check temps at the evaporator inlet (he didn't open up), and considered icing.

I bought four cans of consensor foaming spray cleaner yesterday, but now can't go up to the Sacramento area until Sunday. Because the unit has louvered side panels over the fins, I don't expect to find and bent over or dented fins.

[Boris]

trader_4 wrote in news: [e-mail]:

Hmmm...I'm not quite clear on that. When the unit is cooling the house, the inlet to the evaporator is cold to the touch. I never touched it when the unit stops cooling. I'll have to do that Sunday.

[trader_4]

That's the theory some are working on. I'm with Mr. Burns and doubt it's the issue. If the condenser can't cool sufficiently, then the pressure line going back to the furnace will be significantly above ambient. If it's barely warm, then it has been properly cooled by the condenser and I don't see how cleaning is going to solve it. Any competent tech could tell if the line is abnormally warm by just touching it.

I doubt that's the problem either, but if you can DIY, no harm in taking a look.

[Boris]

" [e-mail]" wrote in news: [e-mail]:

I like that clear, simple, working explanation.

[Boris]

trader_4 wrote in news: [e-mail]:

You know, while I thought the tech said this was fine, I don't remember. If it was fine, then, yes, I probably have other than compressor/condenser problems.

While it may come down to a major repair or replacement, I just dont' want to do that until I've convinced myself it's needed.

Thanks.

[trader_4]

The pressure line, ie the small line, say a foot from the evaporator shouldn't be cool. It should be ambient to just slightly warm. The low pressure line will be cold. And the pressure line real close to the plenum may be cold due to the other end of it being inside the cold plenum. And if you have that, then I don't see how it's an insufficient condenser cooling issue, because, it's cooled.

[Tony Hwang]

I don't remember hearing dirty condenser is causing compressor OH and shut down. Dirty condenser just drops cooling efficiency.

[Tony Hwang]

[Tony Hwang]

If I were you Boris, first when it is running make sure the condenser fan is running, spray water onto condenser to aid cooling, then watch, does it keep running without tripping off? Fan must stay running while cooling(should never stop). Cleaning condenser is not hard. Just remember you have spray water inside out to purge dirt.

[J Burns]

I understand the OP starts out with great cooling, and it takes about an hour for trouble to become apparent. That makes me think something in the system changes in the course of an hour.

The site I found said the drier and the strainer can block the freon. If the drier causes a restriction, maybe it has absorbed all the water it can. A restriction would cause cooling as the refrigerant expands. If the restriction goes below freezing, ice could accumulate until the restriction is bad enough to overheat the pump.

If the drier/strainer is accessible, monitoring the temperatures on both sides would reveal a restriction, I think.

I hope you don't think I'm a troll, just saying that to get you all worked up!

[Tony Hwang]

My second hunch is for some reason I'd replace main contacter inside ODU.

[J Burns]

Looks like you're right again!

I was impressed at how low my split was, but now I don't remember the figure. My AC season hasn't started. When it does, I'll check.

If it's too low, now I know it's a sign of trouble.

[Stormin Mormon]

Almost yes. Too dirty to cool the returning hot REFRIGERANT which is coming back from the evaporator.

See? Like me, you're still learning. I learn new things about mine and other trades now and again.

Best wishes, and please let us know how it goes.

- . Christopher A. Young learn more about Jesus .

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[J Burns]

Uh-oh, I misunderstood. Condenser split is the temperature at which the refrigerant condenses. I guess that's deduced from pressure. The temperature at the outlet would be lower than the condensing temperature.

[Stormin Mormon]

If the condenser is dirty, the inlet to the evaporator may be higher temp than the outdoor air.

- . Christopher A. Young learn more about Jesus .

. .

[Stormin Mormon]

Simple, and incorrect on two points. But, who's counting?

- . Christopher A. Young learn more about Jesus .

. .

[Stormin Mormon]

I'm with you. I don't like to discard equipment that can be repaired.

- . Christopher A. Young learn more about Jesus .

. .

[Stormin Mormon]

It's totally possible. And it was mentioned on the web page I sent a couple days ago, as doing just that.

I see compressor shut down (result of dirty condenser) regularly in refrigeration work.

- . Christopher A. Young learn more about Jesus .

. .

[Stormin Mormon]

I also hate scrapping out equipment unless I'm convinced it's beyond repair.

Some times, it takes a while to get a good diagnosis.

- . Christopher A. Young learn more about Jesus .

. .

[J Burns]

I still didn't say it right! It's the condensing temperature minus the ambient temperature.