Evap coils freezing up- Any advice?

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We've been having problem with our A/C for some time now, the blower/ fan/ heating unit is old, but the outside A/C unit is only 1-year old. I think the inside/ evap coils were also placed new at the time.
We've had problems with charge, which the tech has been out twice to balance, but it could still be mis-balanced charge I guess. In any case, we can't run the A/C for more than 2 hours and the coils freeze up solid, completely iced over. I've taken the cover off to make sure that is the problem, and it surely is. Of course this means we get no air flow and have to turn the system off for many hours to let it thaw out, just to re-freeze when we turn it back on.
I've been reading in this and other groups about possible causes, and read that it could be the charge is wrong, could be dirty/ clogged coils, could be bad airflow. To be sure, I've cleaned the outside A/C unit and coils, but as the unit is still pretty new, there wasn't much to clean, they are good. I got inside the evap coils and there is no visible dirt/ clogging, but still sprayed it out with compressed air, again, no visible sign of it being dirty.
As the fan is old, I suppose it could be going, and it just isn't providing enough air flow, but it is running, and at least doesn't sound like it's having any problems.
Even when the coils are thawed out, and the air is running, it still doesn't feel to me like it should, like I remember it. Furthermore, it doesn't cool the house down, at best it can keep the temperature the same, say around 78-80 while running, but in the 2 hours until it freezes up, I think the air flow is less than it was in the past and it certainly doesn't cool the house. The air is cold, but the flow is weak.
This made me suspect the evap coils were clogged and preventing airflow, but would I see any visible signs if that was the case? Can the fan be going out or somehow working at a lesser capacity when it also isn't giving any signs, at least not audibly? I suppose there could be problems in the vents as well, but I've no idea how to check that.
Any suggestions or advice is most welcome. I'm willing to replace the fan unit, or get other work done, I just don't know what needs to happen. As the A/C unit is still under warranty, I can get the tech out to balance the charge, but he's already done that twice, and quite honestly, that company has turned out to be a huge pain to work with, very unresponsive, very reluctant to do anything and I just want to get the A/C working for my wife and kid who are home all day.
I hope I described the situation correctly, and used the right terms, I have very limited knowledge obviously. Thanks much,
Rock
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Ever think about calling a competent HVAC company?
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Certainly I want to get a competent HVAC company, it seems from some of the responses though that some of you have also dealt with yuppies posing as qualified techs, or companies who are lousy to work with. In truth, to go back before these problems, we went through 3 companies in trying to get our previous A/C unit fixed before having this one installed new, so as a whole, I have shaken faith in these and most companies, all who were all licensed and established.
I'm trying primarily to understand what the problem could be so I have don't get snowed again by having someone come out and replace everything, when it could be fixed by cleaning the coils only, or replacing the blower, ... that kind of thing. Of course I fully understand and don't expect a completely accurate analysis from some internet based conversations, just seeing if anyone has experienced this and have any reasonable guesses.
As for the coils, should I be able to visibly see debris, or does it junk up inside the fins out of sight? Are there any signs of the blower going out that I could check for?
Rock
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we need a whole lot more information before even being able to hazard a guess..... let me ask some questions...... What temp do you have your thermostat set to?? Are *ALL* of your vents wide open?? When was the last time you cleaned/changed your filter??
And some questions for your "tech" to answer.... Make/model/serial for the following... Condenser Evap AHU
What type of refrigerant Was the lineset replaced how deep of vacuum was pulled
Need readings for the following.... SP ST LLP LLT ODT IDT WB/DB
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Thanks stormin M for the info, that is helpful. As for these questions, clearly I don't know all the answers, and can't get my tech right now, but here is what I do know.

72, but for several weeks now have never been able to get that low, the best we've had on cooler rainy days is 74, but average temp is around 80> Are *ALL* of your vents wide open?? -yes, that I know of. Sometimes I close one of the basement vents to try to push more air upstairs, but this is off and on, and the freezing over of the coils is the same either way.
also, all my returns are open, and just to try and get more air going in the return, I've also tried leaving the slot open where the filter is, not effecting the placement of the filter. No difference though either way.

pretty regularly, it is a rather thin one that fits, so I swap it out every month or two. There is a new filter in the system now, I swapped it out about 2 weeks ago.
For the rest of the techy answers, I'm afraid I don't know of course, and it will be a few days before I can reach the tech, I'll try to get some info though. Thanks

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snipped-for-privacy@gmail.com wrote:

72, but for several weeks now have never been able to get that low, the best we've had on cooler rainy days is 74, but average temp is around 80

one of the basement vents to try to push more air upstairs, but this is off and on, and the freezing over of the coils is the same either way.

pretty regularly, it is a rather thin one that fits, so I swap it out every month or two. There is a new filter in the system now, I swapped it out about 2 weeks ago.

It is an apparent low airflow problem with possible additional problems. Check the blower wheel blades to see if there is any lint buildup on them. Any lint blockage will be on the intake side of the E-Coil where you can not see it from the top view.
Get a tech out there that can take some static pressure readings. http://www.udarrell.com/external_static_pressure_readings.html Learn all you can. It should not be difficult for an average tech to locate the problem(s) & get it working properly.
Is it an oil or gas furnace? Some oil furnaces require the E-Coil to be installed 3 to 6 inches above the furnace to allow proper airflow through the E-Coil.
The tech can not properly balance the refrigerant charge unless the airflow & heatload on he E-Coil is within the proper perimeters. All you need is someone that knows what they are doing & it appears those you have used, - don't know enough. You could end up damaging the compressor, I would NOT operate it to the point where it begins to freeze up! - udarrell
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On Sat, 28 Jul 2007 11:54:08 -0700, snipped-for-privacy@gmail.com wrote:

You're a fucking moron. You let some hacks install a condensor, you don't know for sure if the evaporator coil was replaced and you left the old, crappy ass air handler in place. You surely got what you paid for dumbass.
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While you have many different answers no one have mention that it could be possibility of mismatch condenser vs evaporator coil and your AC should be able to run 24 hours per day with out freeze up if everything is matched properly and working ok Tony

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Only if there's enough heat being absorbed by the evaporator.
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That is a really stupid response.
Please stop wasting space on this planet unless you have something to contribute.

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Why, don't you understand that his comment is wrong?
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Thanks to all of you who have offered ideas and suggestions, it gives me a much better idea of what to check against when we have someone come out to service the unit. We'll get someone new out here, and make sure they check all the different points that have been brought up, which is why this information is useful. I certainly never intended to try to fix the problem myself, but I feel much more confident in talking to the new tech we get out here. I hope we'll get it worked out!
Rock
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Nothing worng with his comment , you just didnt read it properly and added some insane bullshit in your head and then vomitted a few words to make you think you are smart. Do you feel smart?
Im glad ;)

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you
If you think his comment is correct, you must be a dipshit too.
What do you thinks going to happen with a system that runs 24/7 that doesn't have the required heat for the evaporator to absorb?
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Pot, kettle, black
*PLONK*
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That was said before moron
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Said before, when? It's not in your post and you make no reference to it anywhere.
You're so clueless that you're making Stormy out to be a genius!
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There's really only two reasons that a resi-system will freeze-up (assuming a matched system was installed).
First, low on refrigerant. Locate leak, recover refrigerant, repair leak, change filter/drier, pressure test, evacuate and then properly charge the system.
Second, airflow issue... many things can cause this. Inadequate ducting Dirty evaporator coil Restrictive air filter Dirty blower wheel Improper blower speed Faulty blower motor Closed vents etc
In order to find the cause, you need a competent tech which will gather the required information to correctly diagnose your system.
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Only two reasons eh??
How bout i quote your other post to me
"If you think his comment is correct, you must be a dipshit too.
What do you thinks going to happen with a system that runs 24/7 that doesn't have the required heat for the evaporator to absorb?"
So that would be three reasons....thought you said two???
And then you mention a third??
Maybe you are having trouble counting??
I have a fourth
How about a bad tev....stuck open??
and if ya wanna get really stupid we could call setting the tstat at 55 f a reason too but thats not enough heat which is the third of your two reasons
Now if ya wanna go back to Stormys post, when he said a system should be able to run 24/7 , it was impliede that there was a "demand"/ load.
And yes He is right....a system should be able to run 24/7
Actually a properly sized system in a high humidity area, at max load is designed to run 24/7
If it ran less it would not remove enough humidty.
Gotta remember, not everyone lives at you trailer park, some people live in other states and even other countries.
Seems all you guys can have a reasonable conversation about is the price of freon and copper. Everything else is just a bitchfest.
For fucks sake grow up and get out of the playground.
Ta ta Jackass.
James
P.S. TOP TOP TOP TOP TOP
yer welcome

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Are you that fucking stupid?
Other comments/facts are inserted.

I said there's really only two reasons for a resi-system to freeze. That doesn't mean there's only two, but that there's two that will normally cause the issue. Low ambient temps will cause issues in some commercial apps, this doesn't normally happen on resi-equipment.

doesn't
So a normal functioning system is going to run 24/7 without satisfying the stat? If it does, there's adequate heat for the evaporator to absorb, Dipshit! Geez, are you that dumb?

Maybe you're having trouble paying attention. Try comprehending what you read this time.

TEV stuck open? I guess you think an oversized piston is going to freeze an evaporator too? LMAO

a
reasons
Yeah, like people normally have there stat set at 55 degrees... get a clue!

It wasn't Stormy who posted that... it was your brother, Tony. Again, pay attention to what you're reading and *try* to comprehend it!

As I stated earlier, only if there's proper heat for the evaporator to absorb.

Your statement isn't actually true. House's vary and so does infiltration.

in
Wow, you must live in a trailer to be so sensitive to ones post... sorry, I didn't know you lived with your mother!

of
And your post is what? You've helped people here in what way?
I suggest you grow some balls and try to pay attention and learn something.

P.S. it was Sam who jumped your ass about the top posting, not me. PAY ATTENTION!!!!!!
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