AC Not Blowing Cold Air: Compressor Fan Running Fine

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Old 07-06-20, 08:01 AM
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Question AC Not Blowing Cold Air: Compressor Fan Running Fine

Hi all, AC system is 8 years old and stopped blowing cold air.

Compressor fan is running so that tells me compressor is fine? Unless there are other components of the compressor I should check/test; that info would be appreciated. No debris on inside or outside of compressor; it's clean.

Small copper line is hot to the touch, but larger copper line is not really cold (I compared to our other identical AC system which covers another part of our house).

Is this a sign of low refrigerant (it uses R410a) or are there other possibilities/things I should check?

My goal is to at least perform the diagnosis, as the HVAC techs here charge an arm and a leg and it's hard to get any sort of upfront pricing unless you ask about specfic repairs like "what is your pricing for an R410a recharge per pound?"

Thanks in advance.

Outside AC compressor specs:

 
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Old 07-06-20, 08:10 AM
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The fan is separate from the compressor although they typically share a capacitor. You should be able to hear the compressor running with a low buzz noise. You should also hear the refrigerant making noise in the lines.

Are you getting any airflow out of the vents?
 
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Old 07-06-20, 08:11 AM
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Hi, yes there is airflow out of the vents, just not cold air.
 
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Old 07-06-20, 08:16 AM
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Do you hear the noises I mentioned?
 
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Old 07-06-20, 08:35 AM
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Yeah, it makes your typical condenser buzzing sound. I even compared to our other identical [and properly functioning] AC system (since we have dual-zone in our house) and both condensers sound exactly the same.

As far as "you should also hear the refrigerant making noise in the lines" would I hear this on the lines outside, or inside? What does it sound like and do I need to put my ear up to them?
 

Last edited by ArchitectureFan; 07-06-20 at 08:51 AM.
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Old 07-06-20, 08:56 AM
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Hi, you said that the suction line wasn’t really cold, ideally it should be sweating, is your filter clean, is the inside coil iced up?
Geo
 
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Old 07-06-20, 08:59 AM
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Hi yes, put in a brand new filter yesterday to ensure it wasn't the filter.

Other pertinent info: All vents are in open position, and I'm using a Nest Thermostat "E" as our thermostat (which has been working fine since I installed it a few months ago).

How do I check if the inside coil is iced up? Where is it located?

Thanks again.
 
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Old 07-06-20, 09:02 AM
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What does it sound like and do I need to put my ear up to them?
Normally you don't even have to have your ear to them to hear it. It sounds like when you have air in a water pipe, kind of a gurgling or woosh-woosh sound. You should hear it anyplace you have access to the lineset. For example, my lineset goes through the basement joists and I can hear it making noise from about 4' away.

If you do not hear the noise then you are likely low on refrigerant and have a leak in the system.

If the coil is iced up you would not have very much airflow out of the vents. A coil icing up is also a sign of low refrigerant.
 
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Old 07-06-20, 09:18 AM
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I don't really hear any distinguishable noise, not even on my other [properly functioning] AC system. Could be that the sound is drowned out by the condenser outside, or the blower inside, as these are the only two places I have access to hear/see the lines.

However, when I put my finger on both the larger and smaller lines, I can feel what feels like liquid flowing through.
 

Last edited by ArchitectureFan; 07-06-20 at 09:39 AM.
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Old 07-06-20, 11:11 AM
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Small copper line is hot to the touch, but larger copper line is not really cold
Is this a sign of low refrigerant
Yes..... since the small line is hot you know the compressor is running.

You don't always hear the refrigerant..... but if you could.... it would be near the air handler.
 
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Old 07-08-20, 09:35 AM
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Decided to have a recommended HVAC technician come out since their diagnostic fee is only $75 and gets applied to whatever future repair.

The tech said the system was low on refrigerant but then also showed me that the inside coil was all rusted, and the leak detector detected a leak from the coil as well. So the tech said the coil needs to be replaced. Luxaire/York apparently is/was not using aluminum coils, which is why it rusted out, according to the tech, and the tech will try to find an aluminum one that will last longer.

The part may or not be covered under warranty (they have to check with manufacturer, unit is 8 years old); if out of warranty the coil part cost will be a ballpark of around $300. And estimated time to replace the inside coil is 4 1/2 to 5 hours (around $650 for labor).

Does that parts and labor estimate sound about right?
 
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Old 07-08-20, 09:44 AM
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Age of system is always a consideration. Based on a 8 year old system..... I'd go for that repair.
The repair estimate is fair and right in the ballpark.

Replacing evaporator coil
 
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Old 07-08-20, 01:32 PM
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Hi, you obviously don’t live in SW Fl. contractors here wouldn’t even consider just replacing only a coil.
Geo
 
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