A/C not cooling in apartment

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Old 08-05-15, 10:48 AM
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A/C not cooling in apartment

Hi,
I am having a problem with my AC cooling. This is a system with the unit outside and then another part in a closet inside where you change the filter and and it has the drip drain, etc.
I have lived here for 3 years and the unit has always had problems. It will either 1) not blow cold or 2) not blow with any flow. For both of these they have always told me that it needed "charged" and it would then work again. This time I thought it was starting to slack by not blowing cold enough and they came and charged it. It did not get better. Then a couple days later it stopped blowing with good air flow and they did something else to make it blow well, but it is still not cold. It is currently hot out (I live in SC), but no hotter than any previous summer and no hotter than a couple weeks ago when it was just as hot.
I have the temperature set on 69 and it is staying on 69 but gets no colder to let the system break. Normally the system would kick on at 70 and then cool to 68 when set to 69. Last night it ran from 9:00 when I got home until 2 when I went to bed and I'm pretty sure it reached 68 and shut down for the 1st time at about 7 in the morning.
I bought a thermometer from the auto parts store (looks sort of like a meat thermometer) and put it into the vent and it reads 64. They tell me it is charged and there is nothing wrong with it and it is just running hard because of the heat outside even though this has not been a problem in the past.
I think they probably know there is another problem, but I do not know enough to ask if this or that was checked.
I would greatly appreciate any help/advise.
Thanks,
Shaun
 
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Old 08-05-15, 11:38 AM
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What has been the outside temp the last few days? Take a temp reading at the return air vent, let us know.
 
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Old 08-05-15, 11:48 AM
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You say the thermostat is set to 69f and the AC is cooling the apartment to 69f. And professionals came out and checked the system and said it is working properly. I fail to see what the problem is?

First, make sure you have a clean air filter installed. Depending on your apartment it may need changing monthly but a clean filter will help your AC operate better and more efficiently.

Previously you say you've seen the temp drop to 68f. The thermostat was probably turning the AC off at the set temperature. Most thermostats turn off the AC compressor at the set temperature but continue to run the fan for a minute to get the last bit of cold out for efficiency. During moderate weather this could be enough to tick it over to display one degree colder.

With the humid, sunny 90++ days we've been having for two months your AC is having to fight to get it down to 69. Just be glad your unit is able to get it so cold inside your apartment and please don't be shocked when you get your power bill. 68 or 69 is fine for a winter heat setting but I prefer 75f for summer cooling to help keep the power bill reasonable.
 
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Old 08-05-15, 12:02 PM
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Thanks for trying to help. Last few days it has been in the 90s, but that is normal. It was near 100 at the beginning of july and it worked great then.
The way this system works is that if I have the temp set to 69, then it kicks on at 70 and runs to 68 and shuts off shortly after reaching 68. Problem is it is not reaching 68 like it always has. 69 seems to be the lowest it can get to and it has to keep running to maintain.
 
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Old 08-05-15, 12:10 PM
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I looked for the air return and I am not sure where it is. I read on another thread that it is like a regular vent but it sucks it and I cannot find that. Could it be on the unit inside the closet? I assume it is around 70 because the air inside is maintaining about there.

Is the way I tried to measure the output sufficient?
 

Last edited by Shaun5142; 08-05-15 at 12:12 PM. Reason: Correct typing from a phone
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Old 08-05-15, 01:02 PM
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I bought a thermometer from the auto parts store (looks sort of like a meat thermometer) and put it into the vent and it reads 64.
If the return air is even close to 70, then your output of 64 is way to high. You should have at least a 15 - 18 degree temp difference. Either the system is not charged correctly or there is something wrong with the refrigeration metering device.
 
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Old 08-05-15, 01:15 PM
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You should have an air return somewhere. Generally they are big like 20" square louvered things in the wall, ceiling or floor. It will be out in the open unless you have put furniture in front of it or a rug over it. If you have anything blocking the air return it needs to be moved. The return needs a very free, good supply of air or your system will suffer.

Once you find the air return stick your thermometer in there when the system is running and note the temperature. Then do the same with a register (air blowing out) and note the temperature.

Another thing to check is to go around to all of your registers and make sure they are open. Then make sure they all have air blowing out of them when the system is running. If you find one that's open but not blowing air it could indicate a problem with the duct.
 
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Old 08-05-15, 01:17 PM
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Thaanks Tom. They did not mention anything about the refrigeration metering device being checked. Is that something a professional is required to check or could I verify it?
 
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Old 08-05-15, 01:25 PM
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To measure the temperature at the output vent I stuck the measuring end of the thermometer about 2 inches into the vent. If that was the correct way to take the measurement, then it seems from what you all are telling me that there is a definite problem with a reading of 64 degrees.
 
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Old 08-05-15, 02:14 PM
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If your room temperature is around 70, then your return temperature is about the same 70. So, as mentioned, your cold input air is 64 which is too high, should be around low 50s (51-55). common cause is low charge, metering device issue is rare. plus you said they charged it up before , then you OK, so may be this time they did not charge enough. If the charge is normal, then you may have metering device or other problems (The reason they have to charge the system all the time is because there is a leak somewhere and that should be fixed).
 
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Old 08-06-15, 04:56 AM
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I measured the cold input air again last night and it was 60 at 2 different vents. Maybe lower than earlier in the day because it had cooled outside? There was also another maintenance report left saying that they had checked everything again and it was working great, so they may have charged it again even though they said that they did not.
I cannot locate the air return and I looked on every wall in this 2 bedroom apartment.
Thanks everyone for helping.
 
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Old 08-06-15, 05:01 AM
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All you need is a good air-temp probe thermometer (digital reading in tenths preferable) an HVAC Supply might sell you one; or use your mercury TH & estimate the tenths; if you don't have a humidity gauge, you need to get one ASAP; a low cost 'INDOOR Humidity Monitor' - ACU-RITE Digital (Excellent) only $8.94 at Walmart Mart or over the Internet; it shows you if %RH is OK, etc..
Check to see if it registers the temperature correctly; if not, take it back for a full refund.

Need the Indoor percent of relative humidity - in the middle of the rooms or, at Return-Air inlet grilles ___%RH
Indoor Return Air Temperature __F Indoor Supply-Air Temperature __F
Subtract Indoor Supply-Air Temp from Return Air Temp __F
Indoor temperature-split = __F

Outdoor condensers discharge-air-temperature ___F
Subtract Outdoor air temperature: __F

Outdoor Condenser Air-Temp-Split ___F

Reply with Quote Fill the #numbers in where the blanks are. Easy Safe testing of your A/C or heat pump cooling performance for all forum visitors to use.
 
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Old 08-06-15, 06:20 AM
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What was the room temperature at the time you took the cold air temperature? If it was 70, then 70-60=10 still not good, you need at least a difference of 15.
Don't worry about the return air temperature, just use room temperature.
 
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Old 08-06-15, 06:38 AM
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The room temp was still 70.
 
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Old 08-06-15, 07:25 AM
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Are they AC techs ? or general maintenance people ? You need to tell them the (70-60) temperature difference (we call it Delta-T) is too small. You need much colder air comes in to the room, prefer 55 or below. If they can only do 60, something is wrong.
 
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Old 08-06-15, 07:45 AM
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They claim to be "certified". By who, I do not know. Is there ine certification board or state? Or can anybody set up an organization and certify people?
What I am getting is that "it is blowing cold and witg force, so what elsr coukd we do? It works." They are expecting me to drop it there and live with it I think. I am sure they know it is not right.
 
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Old 08-06-15, 08:10 AM
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If you think the air is cold enough and it keeps the room comfortable, I guess it is OK, it is really up to you. If this is your own house, and you pay for the AC repairs, then I'll insist top performance (delta-T at least 15), if this is a rental, you may have to take whatever you can get (or move). The only difference here is your AC (with 60 cold air) will run a little longer to get to the set temperature, and you will pay a little more on your utility bill.
 
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Old 08-06-15, 10:45 AM
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If you're paying the electrical for the A/C cooling 'then you don't want it running all the time' to keep U cool. It will pay U to take 5-minutes to log some data...

All you need is a good air-temp probe thermometer (digital reading in tenths preferable) an HVAC Supply might sell you one; or use your mercury TH & estimate the tenths; if you don't have a humidity gauge, you need to get one ASAP; a low cost 'INDOOR Humidity Monitor' - ACU-RITE Digital only $8.94 at Walmart Mart or over the Internet; it shows you if %RH is OK, etc..
Check to see if it registers the temperature correctly; if not, take it back for a full refund.

This form is for anyone to use to have us analyze your HVAC system's performance, if we find problems you'll need to call a Contractor to fix the problems. Many systems are functioning way, way below their mfg'ers performance Ratings; the average was found to be less than 60% of their Rated Btuh.

Because few Techs actually test the Delivered HVAC system's performance It is time for you to run an easy, totally safe, A/C Performance test of your own. No Kids; do not lay anything on top of the outdoor condenser, & hang onto the thermometer so it doesn't drop into the fan!

If we find problems, you will need to contact & qualify a good HVAC Contractor to fix those performance problems.


1) Helpful: condenser 'Tonnage' & SEER Rating of Unit &/or model number: Yours: ______
FIRST; We need to know the 'Indoor' % of Relative Humidity__ %RH
Also, (not critical) however, it's very helpful to get outdoor humidity from online weather info, etc., & wind direction ____, & velocity ___mph, & outdoor ___%RH, outdoor-temp ___F: (Optional)

Weather Forecast by Zip Code

2) TXV or, orifice metering device? __. Only if U know; not critical at this stage.

3) Outdoor condenser’s discharge-air-temperature ___F
Subtract Outdoor air temperature: __F

Outdoor Condenser Air-Temp-Split ___F

4) Need the ‘Indoor’ percent of relative humidity - in the middle of the rooms or, at Return-Air inlet grilles ___%RH

5)Indoor Return Air Temperature __F Indoor Supply-Air Temperature __F
Subtract Indoor Supply-Air Temp from Return Air Temp __F
Indoor temperature-split = __F

“Reply with Quote” Fill the #numbers in where the blanks are. Easy Safe testing of your A/C or heat pump cooling performance for all forum visitors to use.

First, make sure the return air filter is clean, and then you should get a digital probe thermometer that reads in tenths degrees, (though U can use any mercury thermometer) and a low cost percent relative 'humidity gauge 'to check the 'indoor' humidity level.

If you have an air conditioner that was manufactured between 1992 and 2005 it will 'probably be' a 10 or 12 SEER (though some were higher SEER even back then) R-22 refrigerant units.

When the temperature reaches around +80F to +95F outdoors and the indoor temperature is 80F and the relative humidity indoors' is right around 50%RH the outdoor condenser temperature split should be around 20F above the outdoor temperature.

If the indoor temperature is 75F and the relative humidity is 50% then the air discharge temp-split off the condenser should be around 17F.

The indoor temperature-split for all SEER Ratings between the return-air & at the supply air grille closest to the air handler @50%RH should be 18 to 20F temperature drop with either an 80F or 75F indoor-temp. I didn't see my other post...
 
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Old 08-07-15, 01:17 PM
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Thanks again to everyone who replied here. I do appreciate the help. Unfortunately I have been convinced that my apartment is just lying to me. I just spoke to the maintenance guy (certified) and he tells me that all of his readings are good. He tells me that the air temp at the vents that I measured at 60 degrees is not relevant to determine this. I had to really pin him down to get him to say that. He gave me several other readings that I am sure he knew where over my head. If anybody does know of a type of system where that is not relevant, then please doet me know. I live on the 2nd floor of an apartment with part of the unit on the ground (rectangular with the fan in it) and the other part of the unit (part with filter) in a closet with a vented door.
 
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Old 08-07-15, 02:26 PM
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Let us know what he said .. and post his readings here so we can tell you how to respond..
 
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Old 08-07-15, 11:06 PM
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He didn't tell me all of the readings. He said he measured something outside and it was 42 degrees. He was telling me that when I was trying to get him to tell me what they got at the vent. If this helps, I uploaded some pictures I will link below. Thanks again.

Model of outside unit:

http://i416.photobucket.com/albums/p...2/DSC00845.jpg

Outside unit:

http://i416.photobucket.com/albums/p...2/DSC00837.jpg

http://i416.photobucket.com/albums/p...2/DSC00840.jpg


Inside Unit:
http://i416.photobucket.com/albums/p...2/DSC00846.jpg

How I measured temp at vent:
http://i416.photobucket.com/albums/p...2/DSC00851.jpg

Thermometer I am using:

DSC00852.jpg Photo by shaun5142 | Photobucket

http://i416.photobucket.com/albums/p...2/DSC00854.jpg

http://i416.photobucket.com/albums/p...2/DSC00853.jpg
 
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Old 08-08-15, 10:01 AM
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From the pictures, you have a 2 ton Goodman heat pump, but out of the 3 condensers, I don't know which one is yours, looks like there is a fourth one. Anyway, the 42 degree may be the large pipe temperature at outside of the condenser, which is good, but this one good measurement does not mean you get cold enough air into the room, other factors may prevent you from getting cold air into the room, for example, air duct leak, dirty coil, metering device issues, etc.. So we always use Delta-T first before get into individual components. Delta-T is an overall indicator, another word, everything must be good before you can get a good Delta-T 15+. You can verify his finding by check the outside pipe temperature, or just hand feel the pipes at the condenser (find out which one is your condenser), when the system is running, the large pipe should be ice cold and sweet, the small one should be a little warm. If outside unit is OK, then the problem may be in the air handler (inside unit) or at air duct. If he is a licensed AC tech, he should know what Delta-T is. ask him why can't you get Delta-T 15+ ? is the air duct leak ? bad metering device, or dirty coil ?
 
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Old 08-08-15, 11:53 AM
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He is telling me his explanation in 2 parts: 1) It is very hot outside. He is correct here, but it has been this hot before. 2) He was asking as if he didn't understand Delta-T. I asked him 3 or 4 times what the temperature was coming out of the vent and he kept saying other things. When I pinned him on it I said "so you are telling me the temp at the vent (where I had the thermometer in the pic) is irrelevant to determining if the system is working?" He said yes, that it was not a factor.
 
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Old 08-08-15, 12:16 PM
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Also, mine was in the middle. The 2 shorter ones are the same.
 
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Old 08-08-15, 01:58 PM
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I don't think he is a licensed AC tech. In fact, Ac tech costs $120-$140 per hour, The apartment owner is not willing to pay that much unless they have to. You may want to discuss with the owner and tell him you did not have this problem before, and see if he can send a real AC tech to handle the problem. Tell the owner this guy may be just (owner should know) a general maintenance person, he won't be able to fix this AC problem.
 
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Old 08-08-15, 02:05 PM
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Thanks for the help Clocert. From what I have learned here I think they are just trying to avoid fixing it. Over 1,000 units where I live, so the cost of even replacing the whole system if needed would not kill the bottom line. Very irritating. With any training it would be hard to believe he does not understand the Delta-T.
 
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Old 08-08-15, 06:54 PM
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AS I mentioned, with 60 degree air (Delta-T at 70-60=10), your AC will run longer to get to the set temperature because the air is not cold enough, so you will have to pay more for electricity. other then that, no difference.
 
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Old 08-11-15, 09:34 AM
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I just had a face to face with the maintenance person. The manager was supposed to be here too but was a no show.

She still insists that it is cooling, so there is no problem. She told me that the delta T of 15 only applies to newer systems and not this one. Is that true? How long has Delta T = 15 been a good indicator?

Thanks
 
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Old 08-11-15, 12:39 PM
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I just had a face to face with the maintenance person. The manager was supposed to be here too but was a no show.

She still insists that it is cooling, so there is no problem. She told me that the delta T of 15 only applies to newer systems and not this one. Is that true? How long has Delta T = 15 been a good indicator? Thanks
Delta T varies as to the % of the Indoor Relative Humidity.
For example with average indoor ooutdoor heatload conditions; with the new systems, when the indoor humidity is close to 50% the indoor temp-split should be around 19 to 20F.

A the %RH goes up above 50% the temp-split is less; as %RH goes down below 50% the temp-split will be higher than 20F, on a graduated scale.

No; it does not just apply to newer or older systems; at least back to 1992 when 10-SEER was required. Some of the older lower SEER unit hid have even higher temp-splits.

The info you got was faulty...it may not be performing well...!
 
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Old 08-11-15, 01:45 PM
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As mentioned by HAVC RETIRED, Delta-T is vary based on Humidity (between 15 and 20). 15 is the lower limit even you have 90% humidity, drier room should have higher Delta-T, So, in short, anything lower than 15 is not acceptable, it has nothing to do with the age of the system. (She said it is cooling, sure, but the problem is NOT enough cooling.)
 
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Old 08-12-15, 08:24 AM
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One more thing to consider. If your apartment building is not insulated well enough, or the attic area is not ventilated well enough, it may affect the delta-T when you set the T-stat temperature too low (70 is considered a little bit too low while outside is above 90). To be fair, set the T-stat temperature at 75 while outside is 90, and see what the delta-T is.
 
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Old 08-12-15, 08:41 AM
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I checked it testerday when temp was low 80s and still got 60.
 
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