AC acting up-Not cooling properly

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Old 08-05-13, 06:58 PM
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AC acting up-Not cooling properly

Our house was built and purchased in 2009 (only 1300 sq ft, one level). In 2010, we had to replace the evaporator coil in our AC unit. Don't know if any of that is relevant but want to provide all possible details.

Just last week, my husband smelled burned plastic in the hallway where our thermostat and return are. Ever since, our AC has not cooled like normal. Only 3 rooms seem to be getting cold air now (those closest to unit outside). Other rooms have lower air flow coming from vents and air is barely cool. House gets up to 80 during the day but will not drop past 75 at night.

Air filter has been changed and we use the cheapos so it doesn't pull too hard. A friend came to check out the unit. Said lines were gunked up and cleaned them. That didn't help. He came back and replaced capacitor...that didn't help. All ductwork and dampers have been checked and are okay. He couldn't find anything else wrong with the unit. So we called a professional. The only thing he found was that we were a little low on coolant. Recharged to proper superheat. This did not do anything. Thermostat reads 75 right now even though it is currently cooler than that outside.

Any suggestions would be greatly appreciated! Feeling very frustrated and are out $250 for nothing!
 
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Old 08-05-13, 07:46 PM
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Does ac run constantly? OR does it cycle? Is thermostat working properly?
 
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Old 08-05-13, 07:57 PM
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It runs constantly. Not sure if thermostat is working properly. It says 75 right now (currently set at 68), but it feels cooler than 75 since we have fans running. Definitely warm in the 2 rooms directly across from thermostat though.
 
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Old 08-05-13, 07:58 PM
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is anything frozen? Evap coil or lineset?
 
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Old 08-05-13, 08:00 PM
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Not according to either of the 2 people that checked it out. . .
 
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Old 08-05-13, 08:03 PM
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those are things you can check.........
 
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Old 08-05-13, 08:11 PM
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I know the evap coil was checked and was ok. One of the guys that came out even termed this a "ghost problem" because he couldn't find anything wrong. Could a thermostat issue be causing our problems? Wasn't sure if that was possible since some rooms are cool and some aren't.
Would turning the AC off overnight and back on tomorrow possibly help if something is frozen?
 
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Old 08-05-13, 08:13 PM
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were the rooms that were warm cooling when the tech was there? If they were warm instead of cool then you could term it a "ghost problem"..... Do you have a zoning system? Are you going to verify if anything is frozen?
 
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Old 08-05-13, 08:25 PM
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Nothing changed when the tech was here or after he left. Those rooms were/are still warm with very little air coming from vents. I honestly think he was just as stumped as the first guy and was hoping more coolant would help. He got out of dodge pretty quick without determining if it was actually helping. I will be calling them back tomorrow.
I'm sorry but I'm completely clueless about this stuff; what is a zoning system? And I have no idea how to check if something might be frozen. We have turned off the unit, just in case, since it's a little cooler outside tonight. If something is frozen and we give it time to thaw, will that fix it?
 
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Old 08-05-13, 08:41 PM
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Shutting the system down and not verifying if it is frozen can lead a tech astray.... Thawing out a frozen coil will relieve a symptom but will not solve the cause. Have you verified the filter is clean?

Determining if something is frozen is a visual check..... (something you can do)

IF you are calling someone back out then I suggest you ask for a senior tech...
 
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Old 08-06-13, 02:50 AM
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Well we ended up turning it off for only about 20 minutes before it jumped up to 78 degrees inside (it was low 70s outside). Turned it back on. Filter is clean. I will check for anything frozen once it's light out and will be sure to ask for a senior tech when I call back. Thanks for your help. )
 
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Old 08-06-13, 04:57 AM
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When Kevin asked you if you had a zoning system, he was referring to your statement that the two warm rooms have very little airflow coming out of the vents. If it's a single zone system (which it likely is considering it's a single level, 1300 square foot house), there shouldn't be a sudden loss of airflow from some of the vents. Is there normal airflow from the other vents, are is it low from them as well? I'm suspicious that your evaporator coil may be frozen. A classic indication of a frozen evaporator coil is low airflow, however that would affect the entire house, not just a couple of rooms (assuming a single zone system).

Usually, there is an inspection cover that can be removed, allowing access to the evaporator coil. If you want to check it, find the cover, and run the system for an hour or more (cover on). Then shut the system down, remove the cover and look at the evaporator coil. If it is white with frost or ice, then it's frozen. A frozen evaporator coil is usually caused by two things. Either the system is low on refrigerant, or there is insufficient airflow through the evaporator coil (plugged air filter or blower not running at proper speed).
 
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Old 08-06-13, 10:09 AM
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Yep, seems the evap coil is frozen. Tech is here now. Don't know how his colleague missed that yesterday, but this guy seems more knowledgeable. Hoping he doesn't require my first born as payment. . Thanks Bob14525!
 
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Old 08-06-13, 11:40 AM
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So the final verdict. . . .relay was bringing heat strips on. Had to replace contactor and rewire strips to it instead of relay. So with yesterday's visit which included only 1# of R22 and today's visit requiring the new contactor, 3 more #s of coolant, and the rewiring it was a grand total of about $850. I hope this info can help someone else out in the future.
 
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Old 08-06-13, 12:21 PM
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So... refrigerant was added.... where is the leak and was it repaired? Ac systems are sealed systems if you are missing refrigerant then there is a leak.
 
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Old 08-06-13, 04:18 PM
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He didn't address a leak but we are already back where we started. Someone is coming back tomorrow. Now the thermostat will not communicate at all with the unit, won't even turn off. So frustrated.
 
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Old 08-06-13, 04:26 PM
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Tomorrow?! If only that sort of thing happened where I work.... IF we screw up then it doesn't matter what time of day it is.... someone shows up that day. Especially talking the kind of money you have paid to the contractor.
 
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Old 08-06-13, 05:31 PM
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Yeah I know. Wish you lived in NC to help me out. Lol. They will not be getting another dime from me until the problem is fixed to my satisfaction.
 
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