A/C not cooling


  #1  
Old 09-18-21, 08:52 PM
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A/C not cooling

Just noticed that the A/C on my main floor not cooling (at 11pm). THe past couple of time, it was a relatively easy fix. Once it was the capacitor that needed to be replaced. The second time it was the relay. Easy fixes. This time though the condenser is still running so it probably something else. It is dark out so couldn't really do to much. It seems like there is still some ice on the line at the condenser.

Turned the system off and will take a closer look tomorrow morning. I am usually good about replacing the filter and the condenser coils are clean.

Hoping it is nothing serious. The system is 18year old so nothing would surprise me.

Any tips on what to check tomorrow would be appreciated.
Take Care all
Ian
 
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Old 09-18-21, 09:38 PM
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If your condenser is running and you are seeing some system frosting.........

Your evaporator coil may have iced over inside. Overnight it will melt so try the system again in the morning. Very important to keep the filter clean. Check and make sure the blower in the air handler is running.
 
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Old 09-19-21, 05:03 PM
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Thanks for the comments.
The air filter was dirty but not too bad. It was time to change so installed a new filter.
Turned system back on this morning. temperature was 77 thermostat was set to 75. And it cooled down to 75 and kept it there most of the day. Thought I might be good.
Late this afternoon, the temperature was back up to 77. System was running but temperature was not dropping. The fitting on the pipe leaving the condensor outside was iced up so I am getting some cooling. Furnace blower is blowing.
Low charge? does that mean there is a leak. This system is 20 years old
What else might I look for?
Take Care
Ian.
 
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Old 09-19-21, 05:17 PM
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You could have a charge issue.
Usually if the evaporator inside freezes over the airflow gets reduced. Are you losing airflow ?
 
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Old 09-19-21, 07:31 PM
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Turned AC off and ran the blower only. Ran it for about 1hr. Seem to have good air flow.Just turned the AC back on and will obswrve to see if I get any cooling.

If it is a charge issue, I am guessing that means I have a leak. So this is a 20 year old system with older freon.
Is there anything more I can do? Is it worth having someone try to find the leak and recharge.
 
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Old 09-19-21, 07:42 PM
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Refrigerant never goes bad or get olds..... it just leaks out.
A typical leak after 20 years would be a corroded evaporator coil.
See if you have an access panel where you could look at it.
 
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Old 09-19-21, 07:46 PM
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So it did cool down from 77 to 74 when i started it back up. No expectation that it will work any better tomorrow.
Been lucky in all of my years of home owhership i have nevwr had a syarem that needed to be recharged.
appreciate any advice you might have on best path forward
 
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Old 09-19-21, 08:11 PM
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The access panel is under 2in of insulation.i have been tempted to cut it off in the past and clewn the coils. I doubt they have ben cleaned in 20 years. I have been in The house for 4 years.
i agree if a leak it is likely in the evaporator coil. If it cmae down to replacing the AC coil any rulea of thumb wet repair or replace
 
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Old 09-19-21, 08:16 PM
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You could check to see if they're rusted where they sit in or near the drip pan.

It would be borderline to change just an evaporator on a 20 year old system.
You could have a tech check for leaks.
 
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Old 09-20-21, 06:27 AM
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Thankful that we are going into fall and the 2nd floor and basement ac are good. One way or the other, i guess I need a tech to come in and check things out. I have been priming myself for a while wrt getting the system replace just given the age but maybe time to given in.
Thanks much for the comments.
 
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Old 09-20-21, 04:14 PM
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System worked again this afternoon but it is not very warm out so not much load. It did drop the temperature when I asked it to.
What would be the most cost effective approach to replacing AC and furnace? I got a quote about 18months ago to replace both the main and second floor AC and furnaces totalling about $14k. How do you decide what SEER rating to go with? I am lucky. We are going into fall so no urgency. Would likely only replace 1 system at a time.
 
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Old 10-03-21, 06:08 PM
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I am back in town and have a little time to try and troubleshoot my A/C system. Symptoms haven't changes. Cools some but eventually can't keep up. Would like to take a look at the evaporator coil but don't want to do more harm than good. I have a carrier furnace air handler 58PAV070. I have attached a couple of pictures of the connections to the evaporator coil but I haven't found any diagrams showing how to open up the panel

I suspect it is going to be quite rusted as the drain line got plugged up last year. When I cleaned it out, it look mostly like rust. Just curious to see what it looks like

This is a 20year old system. I suspect, I am heading towards a system replacement.



 
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Old 10-03-21, 07:31 PM
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To answer your evaporator coil inspection question, the front panel with the Carrier logo on it will come off. It is held in place with a series of screws that usually require a 5/16" nut driver. Sometimes there are a couple on the right edge also. When they are out the bottom of the panel slides out first to miss the top lip. Once it's off you'll see the top of the coil which is not the area that gets dirty, but you'll also see the evap pan which should be clean.. You can usually break it down further to see underneath, but that gets complicated.
Reading the prior posts explaining the problem and good suggestions for a solution it should be clear that a frosting/icing evap coil usually means low air-flow or low refrigerant. Focusing on what you can do aside from clean filter(s) I would look to confirm that you you don't have any closed supply/return vents in the home. I've also seen vents covered or blocked by furniture.
Check the blower wheel in the furnace to make sure it isn't dirty. If it is it's a problem in itself as well as an indication that the evap coil is dirty underneath. A clean wheel would indicate the opposite. A static pressure check or look with a camera would be helpful, but once again it get complicated.
One thing I notice in your photo is that your suction line (bigger one) appears to be rubbing the edge of the case where it enters. The case is vibrating steel, the line is softer copper. With time this can cut the copper and leak refrigerant. Naturally this contact should be eliminated. After the rub is corrected thumb gum, cork tape, or silicone should be used to seal the airflow leaking around it like the smaller line has. I would strongly suggest signing up for an annual "clean and check", "tune-up", "preventative maintenance", or what ever they call it in your area. Good luck.
 
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Old 10-07-21, 05:52 PM
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Was able to get the cover off. and look inside. It is pretty rusted on the ends but don't know how bad that is from normal given the system is 20 years old. I just turned the system on or a few minutes and the bottom coils ends frosted up so getting some cooling. It would certainly be easy enough to clean the two evap panels that are right there from the top side. Tomorrow night, I will try and get the A panel on the left out to see how dirty those 2 coils are from the bottom. 3 of the screws will be easy the 4th is alittle tucked away. I guess I could try cleaning what I can see and see if I see a difference

I am lucky that we are in the fall so I don't have any urgency to get the system fixed or replaced. As a first impressions, is it worth trying to fix or should I consider a replacement system?

 
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Old 10-07-21, 08:40 PM
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While you're at this point I would also check to see if you have a steel drip pan. If so I would be concerned that it could be as rusted as the other steel in the photo. Rusty pans often become leaky pans. One more thing to consider when deciding on a system replacement.
 
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Old 10-08-21, 09:45 AM
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Just the bottom 2-3 coils frosting over indicate a low charge.
 
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Old 10-08-21, 02:07 PM
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Finished opening things up this afternoon. The coils are actually pretty clean. Based on this an PJMax comments and no obvious plugging; Low Charge it is. So there is a leak somewhere.
The pan the coils are sitting in is 3/16 in thick plastic so there shouldn't be an opportunity for a leak in the pan.

The question now is repair or replace. I have a tech coming on Monday to look at system. What would be the break even point for repairs/replace on a 20 year old system.


Both coils in A frame

coil on the right of A frame
 
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Old 10-08-21, 03:24 PM
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Just to clarify, when said "rusty pans often become leaky pans" I was talking about condensate leaking, not refrigerant.
 
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Old 10-09-21, 09:22 AM
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I did understand. The condensate pan looks like it is some kind of PVC about 3/16 to 1/4 in thick. Since I have low charge I think I have a refrigerant leak somewhere. I have a tech coming on Monday to look at the system and will make a decision from there.
I enjoy getting my hands dirty on these type of projects and really appreciate everyone's comments as I ask dumb questions and use the wrong terms <grin>.
I will post back what the tech ends up coming up with.
Have a great weekend everyone
 
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Old 10-12-21, 03:38 AM
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Technician stopped by today. Diagnosed low refrigerant charge. $270 to fix the leak with a "stop leak" compound. No guarantee on repair. plus 1# to more likely, 4# of freon. $250 per lb of freon. ( System uses 4 pounds). Recommend system replacement. I guess I am not surprized. Confirmation of what I already thought I knew $85. In process of getting replacement quotes.
 
 

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