A/C Not cooling properly


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Old 12-30-07, 04:51 AM
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A/C Not cooling properly

I have a rather old console air-conditioning unit. It doesn't seem to be cooling properly lately. Both the evaporator and condensor are free of debris. Compressor seems fine too. Condensor fan working alright as well. When the unit is running, only half the evaporator gets cold, the other half only gets slightly cool. (Its as if the freon "loses steam" half way through the evaporator.) Does this sound like it may be low on freon? Its an old unit so I'm too keen on spending too much money it. Any help would be greatly appreciated.

Thanks
 
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Old 12-30-07, 05:17 AM
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From the symptons you describe, it does indeed sound like the unit is low in refrigerant.

Unfortunately you'll have to put some money into your old unit to get it back in shape. You seem reluctant to do so...but the alternative is to pay for a new unit to replace it.

How old is this console AC of yours?
 
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Old 12-30-07, 01:40 PM
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I'm not entirely sure on the age. But I would say that it is nothing less than 12 years old, based on design, quality of workmanship and lack complicated circuitary. Its in rather good nick considering the humid conditions it works under. Uses R22 refrigerant so its not too old.

Thanks for your help.

Just to add to my previous posting. The liquid pipe leading to the evaporator forms a thin layer of ice on it after 2 to 3 mins of running the system. The returning gas pipe from the evaporator is warm as well.

Forgive the simple terminology...can never remember the correct terms.
 
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Old 12-30-07, 03:54 PM
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You seem familiar with things in this area. Indeed, there is a liquid line whose job is to bring "liquid" refrigerant to the evaporator, and a returning gas line (called the suction line) that brings the "gas" back to the compressor.

What is not normal with this picture is that you are reporting ice forming on the liquid line. That suggests a somewhat plugged "liquid line filter dryer". If this diagnostic of mine is what it is, it would severely restrict refrigerant flow into the evaporator, which would explain why only about half of the evaporator gets cold.

Having said all of the above, I'm not sure how much work you'll be able to do since you'll need some specialized tools. I'd advice you to call an HVAC service provider.
 
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Old 12-31-07, 04:03 PM
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Yeah sounds like a internal sealed (actually leaking used to be sealed) refrigerant system problem, unservicable by uncertified personnell. If you have a EPA cert and can purchase R-22 you could recharge and see how long it lasts but if you try to have someone service it they will quickly run up a bill probably well in excess of the purchase price of a new replacement unit.
 
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Old 01-01-08, 10:03 AM
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Hmmm...I don't where you are going with this...LOL. Anyway, I'll get someone in to look at it.

Thanks again for the advice.
 
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Old 01-01-08, 12:23 PM
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Don't mean to turn you off, we're glad to help, but you really need some tools of the trade, and since the type of work needed will involve cutting your lines open, are you EPA certified? You'll need, by law, to be at least type-I (I believe your unit falls in the small-appliance category).

recovery machine
tubing cutters
vacuum pump
refrigeration gauges
compressed nitrogen
vacuum pump

to name but just a few, are some of the things you'll need to have handy to do this job. And if you did have them, you'd probably have done this job already w/o needing to ask us for help.
 
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Old 01-05-08, 06:59 AM
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Since all the technicians are still closed here, I got bored and fiddled and started cleaning as much of the system as i could...ie dusting off the coils and cleaning out the drip trays etc.

I've been thinking further to your blockage theory, if there should be a blockage in the system, surely the condensor wouldn't get as warm as it normally would?

I also let the system run for about 15 mins out of curiosity with evaporator coils exposed and in the those 15mins ice formed on the first 3 coils or so...and remaining coils were slightly cooler than room temperature. Blocking the air flow through it completely saw it eventually getting entirely cool.

Still suspect a blockage?

Then just another general query. Does an airconditioning system ever need re-charging even if there are no leaks? Surely the freon looses its properties after a period of time and the molecules can escape from the system such as your cars tyre?
 
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Old 01-05-08, 08:08 AM
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Originally Posted by Darkwing19
I've been thinking further to your blockage theory, if there should be a blockage in the system, surely the condensor wouldn't get as warm as it normally would?
A partial blockage would...and so would a low charge product of a slow leak. You're correct, a complete blockage won't cause the condenser to get warm.

Originally Posted by Darkwing19
I also let the system run for about 15 mins out of curiosity with evaporator coils exposed and in the those 15mins ice formed on the first 3 coils or so...and remaining coils were slightly cooler than room temperature. Blocking the air flow through it completely saw it eventually getting entirely cool.
The room air is much more warm than the refrigerant inside the coil...heat from the air is transferred to the circulating refrigerant. When you block the coil you literally stop this transfer of heat so the coil remains cool since is not being permitted to take that heat the air was bringing

Originally Posted by Darkwing19
Still suspect a blockage?
...or a low charge condition product of a very small leak which has been causing the system to slowly be leaking refrigerant over a long period of time.

Originally Posted by Darkwing19
Then just another general query. Does an airconditioning system ever need re-charging even if there are no leaks? Surely the freon looses its properties after a period of time and the molecules can escape from the system such as your cars tyre
Freon was created to last over 120 years without losing its thermal or physical properties. A system that does not have a leak does not need to be recharged. Quite different with older automobilels where you have hoses (with permeability issues) as well as pressure connections. Central A.C. systems have soldered or brazed connections. If a service provider comes to you each year allegedly to re-charge your system, he's either not too competent (since he's not fixing the alleged leak), or worse, not being honest.
 
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Old 01-06-08, 01:19 AM
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Just out of further interest sake...How would the techinician remove the blockage..using nitrogen was mentioned lower down.?
 
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Old 01-06-08, 04:44 AM
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He would have to...
(1) empty the unit by recovering the refrigerant in it

(2) pressurize the system with Nitrogen to see if perhaps a leak is the culprit. identify the leak
(3) fix the leak and proceed with normal charging procedures...evacuation of the nitrogen+dehydration+charging

If no leaks show, then there's a blockage

(2) remove the expansion device (I never asked...but...does yous system have: a- a capillaty tube?, b-a piston?, or c- a TXV?)
(3) connect a nitrogen cylinder via a set of gauges to the unit's service valves
(4) bleed nityrogen thru system...this will show whether the refrigerant control or the filter drier (or both) are at fault
(5) re-install exansion device
(6) pressurize+evacuate+dehydrate+charge
 
 

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