New apartment a/c issue - can't catch up

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Oct 30, 2015
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I moved into a different apartment a couple days ago and was looking for a little advice regarding its a/c.

The apartment is 600ish square feet and in a '60s building so likely not too well insulated by any means. The windows are large, and seem to be two layers of single-pane construction, so they are far from tight.

The a/c in question is a wall-mount unit in the corner of the living room. It's a GE unit from the mid 2000s by what I can gather by googling (no visible model number). It looks like either of the following... a AJCH10DCB or an AJCH12DCB which are either 9,900 or 11,600 BTU (respectively). It's supposed to be rated around 9.5 EER. It's a 220v and 15amp unit based on the two horizontal prongs on the plug. The filter was reasonably clean.

The issue is that it hasn't come close to catching up despite being on for several days. (The room was in the upper 70s when I moved in.) It's been set to the highest fan setting and the coldest temperature, and the lowest it's been able to reach is 72F (measured across the room). Naturally, that means that it hasn't cycled once, and the point at which the mechanical thermostat clicks off is about the 1/3 mark from MIN COOL to MAX COOL (that is, there's 2/3 of the scale where the thermostat does nothing since it can't catch up). The high today was 85F or so, and it was only able to hold 72F while I was at work with the blinds pulled, and lights and appliances off.

I'm not saying that 72F is unacceptably warm or anything, but the behavior seems strange and it certainly can't be efficient running it 24/7/365 to keep merely a ten or twelve degree differential over the outside. Even last night, with the low being around 60F, it couldn't catch up or cool the room below 72 despite being set to the max cool setting. This seems much worse than my counter-example of a comparable window a/c I've used, which could easily freeze out a similar-size room if set to its lowest setting for that long, and could easily catch up and cycle at a normal setting.

Does this behavior seem normal? I'm expecting a big electric bill based on the fact that it hasn't cycled once or been able to catch up. It's also not a good sign for how it might work when the temps climb higher than 85 or so. (The climate is southern Wisconsin, so not hot, but it'll get plenty warm.)

Here's the unit (or a similar one), for reference: https://www.geappliances.com/appliance/GE-230-208-Volt-Built-In-Room-Air-Cool-Unit-AJCH10DCB
 
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what is the air temp its putting out?
is this in a wall sleeve? those are typically quite abit lower efficiency vs window units.
although that seems even lower than normal.. probably around right for a 20 year old one.

You might be better off with a inverter window unit in the bedroom (if that is possible) keep that one running usually MUCH more efficient and supplement as needed with the wall unit.

fairly new 12k btu 220v wall sleeve unit is 10.5eer

a midea 12k btu 115v u shaped inverter window model is around 15 CEER (CEER is more strict than EER)
 
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That is not a lot of btus for a room that size. What floor are you on? I’d measure the air temp coming out of the unit and possibly get a window unit for the other side of the apartment to balance things out. If it’s only 10k btu and you have crappy windows and insulation I’d say it’s doing all it can.
 
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Just based on some quick math you probably need a 15 to 20k BTU unit (probably leaning towards 20) for 1960s construction.
 

TmanP

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I don't have a meat thermometer yet (haven't fully moved in yet) but the temp that it's putting out seems more like "cool" and less like "cold." I can update once I get a reading from that.

To make matters worse, it's a fifth-floor, south-facing unit.

I'd not be surprised that it was struggling at warmer temps, but it's anemic even at ambient temps of 60-80F.

The summers are moderate (not Dallas or anything) - I'm in Madison WI which is a bit north of Chicago, for reference.
 
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Brick building? Full sun? Maybe room darkening shades would help, sounds like the heat load is more than it can handle, usually undercharged means icing up (guessing that’s not happening).
 
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TmanP

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Brick building? Full sun? Maybe room darkening shades would help, sounds like the heat load is more than it can handle, usually undercharged means icing up (guessing that’s not happening).

Yep, it's brick and in pretty much full sun.
Better shades will be an option, as will supplementing with a portable a/c unit in the bedroom and making sure there are no incandescent bulbs here.

I appreciate all the advice from everyone already.

As an update, the ambient just ticked up to 73F. Outdoor is 80F and it's getting dusky (no direct sunlight any more).

to @Rand, it is in a wall sleeve. Each unit has just one (no a/c in any of the bedrooms).

I don't see any signs of icing up on the inside.
 
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Cant swing a window unit? the u shaped midea is 15ceer
the portable ones range from 8-10.5 and if you dont get a dual hose version they will exhaust your cold air and heat the other rooms up.
 

TmanP

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Cant swing a window unit? the u shaped midea is 15ceer
the portable ones range from 8-10.5 and if you dont get a dual hose version they will exhaust your cold air and heat the other rooms up.

I don't think window units are allowed (no one has one) and the windows slide to the side rather than being double/single hung that slide up.
There are three this size and then a much larger one in the living room...
 

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I don't think window units are allowed (no one has one) and the windows slide to the side rather than being double/single hung that slide up.
There are three this size and then a much larger one in the living room...
yep.. portable it is.. I wouldnt replace their wall unit for them.
Dual hose inverter style isnt too bad.. some of the old single hose models are terrible.
 

JHZR2

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What does the landlord say?
Exactly. Take data and bring it up to the landlord. Have photos documenting. You shouldn’t have to buy anything for a rental that claims it has AC.

I agree that knowing the air temps coming out is a major step. Start with that and go from there.

I suspect maybe the coils are iceing up…
 

JC1

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What about the gaskets on the windows? Sounds like poor insulation with a combination of many other things are combining to keep you uncomfortable. How do you clean the fins on those type of AC units? Can they be sprayed with water to clean out any dust or dirt?

Make sure your ceiling fans are going in the proper direction as well.

 
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I would look and see if it has an air filter on the back side. I had a portable A/C unit where I work in our shop and the filter on the back was caked up with dirt.
 

TmanP

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Update: it looks like it's a 9900 BTU model (nominally 10,000 BTU). I took the grille off and found the label:
IMG_0202.jpg
 
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I used to live on the top floor of an apartment in the summer where outside temp is 110F during college. I subleased the apartment because it was 1/2 off when students go back because of the heat, and I calculated that I am getting 50% off on rent and I can take summer classes at 2/3 off discount.

Let's just say it was still 85F inside when it was 110F outside, mainly because the roof gets HOT under the sun, with 1 small wall mount AC like yours in the whole 700 sqft apartment. After that, I decided to never rent the top floor in that town (my parents disagree until I invite them over for a visit with AC OFF one day).

OP your AC is there to keep you from dying, not to make the place a heaven. I'm sorry but if you want better AC you likely have to move, as most landlord would not be able to retrofit that apartment to great comfort and recoup the investment put into it.

In my current moderate climate house, the outside temp can be 81F when my 3 ton AC is still needed to cool the house down before going to sleep, or the top floor could be 81F at night when the outside temp is 69F. Roof traps a lot of heat and release them back into the house at night if AC is not on during the day, even in a 90s house like mine.
 
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It's a PTAC most likely and the landlord could certainly put one with more BTUs in, it's on a 240V (or 208V) 15A circuit.

But this one sounds like it isn't working right. Could have a leak and be low on charge. If that's the case it will eventually completely fail.
 
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It probably needs to have the condenser cleaned out. They get packed full of lint and dirt and the unit will stop cooling. Your landlord will probably not want to do that since the whole unit will have to be removed to get at it.
 
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I once lived on the top floor of a high rise. I had to run the a/c most of the time from May thru early October. If you live on the top floor of any apartment building, your 10k btu unit may never catch up.
 
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