Air conditioner troubleshooting?

[Dessert Tears]

Fortunately, a mouse did not pop out of my air conditioner. My wall unit air conditioner cools for a while, then becomes ineffective. Last year, the building handyman looked at it, said it was low on refrigerant, and supposedly recharged it. I wasn't there, so I didn't see what he did. It didn't seem to help then, and the behavior was the same last month.

When turned on after resting for at least a day, the AC blows cold air for roughly 30 minutes. The sound changes, but not to fan-only mode, and the air gradually warms to room temperature. If it is left running, cold air will return after 45-60 minutes. Longer runtime and hotter outside temperatures seem to shorten the cold and lengthen the warm periods.

Any thoughts or suggestions? The unit is bulky and probably heavy, so outright replacement will be difficult.

 

[mmntech]

Coolant leak? Bad thermostat?

 

[BoomerD]

Dirty coils?

 

[zinfamous]

dare I say it??

 

[BoomerD]

dare I say it??

Covered in the OP...

 

[Ichinisan]

Read topic title.

I've suffered the same thing for YEARS and the maintenance guys at my apartment complex have been unable to resolve it.

This is going to be a miserable summer...

[edit]
Read OP.

I have exactly the same issue. I'm in Newnan, GA...and it's @#$%ING HOT!

 

[Dessert Tears]

Coolant leak? Bad thermostat?

I think it isn't the thermostat because it sounds different (compressor still going?) from the normal fan-only switchover when compared to an identical unit we have in another room. I might have tested it by playing with the temperature setting on a relatively cool day, but I'm not sure.

Dirty coils?

I vacuumed both the fins and the intake filters. If the coils vent to outside, I don't have access to them, but I could ask the handyman to check.

BTW, I could use an air conditioner primer, if someone has a link. I got HVAC and central air information when I searched on Google.

 

[BTA]

Sounds like the compressor is shutting off when it shouldn't...possibly bad, possibly a coolant leak and needs a charge/service again.

I'd just get someone else to look at it.

 

[BTA]

Oh you said handyman...there's your problem.

Good luck.

 

[Dessert Tears]

I have exactly the same issue. I'm in Newnan, GA...and it's @#$%ING HOT!

I sympathize. It's not hot here yet, but once it heats up.... The maintenance queue was backlogged when we tried to get it fixed last year. I don't know if it was all the AC requests or if it's always like that.

 

[DominionSeraph]

You sure it's not icing over?

 

[zzuupp]

You sure it's not icing over?

in 30 minutes???

I did consider that, but the time isn't right

 

[DominionSeraph]

in 30 minutes???

I did consider that, but the time isn't right

If it's humid they can ice up fast.

 

[herm0016]

if its over charged or under charged it will ice faster. that was my first thought.

 

[BUTCH1]

You sure it's not icing over?

That's what mine was doing at the end of last summer, it has a slow leak at the evaporator, needs charging every 3 years or so. OP, your has a leak too but a much worse one it seems..

 

[Vette73]

Unless its some super crazy nice one just go spend $200 or so at lowes or any other place and replace it.

 

[grrl]

Sounds like the compressor is shutting off when it shouldn't...possibly bad

That's what it sounds like to me, the compressor could be failing. When it gets too hot it cuts out, then when the windings cool down enough it starts back up again. Can you still hear the compressor when it starts to blow warm air?

 

[MWink]

I had a somewhat similar experience with my window AC this year. I noticed that it was not cooling nearly as well as it used to. It would work for a while then become less effective. Also the compressor would cycle off more frequently than I thought it should. When I plugged it into my kill-a-watt I discovered the power usage was about 75% above it's normal draw and would increase when I turned the fan speed down.

I finally decided to try cleaning the condenser coils (outside part). They didn't look dirty from the outside but when I looked at the coils on the side inside the unit they were quite dirty. I tried some brushes and compressed air but it didn't do much. I finally decided to take a hose and blast it with water. I spent a good half hour blasting disgusting gunk out of the unit.

It seems to have worked. The unit is now blowing cold, running the compressor as long as necessary, and the power draw is back to normal. I'd suggest you try cleaning the condenser coils. If you use my method, make sure you unplug it first and let it dry after!

 

[ballmode]

check for mice

 

[Dessert Tears]

Thanks for all the replies.

I think it isn't the thermostat because it sounds different (compressor still going?) from the normal fan-only switchover when compared to an identical unit we have in another room. I might have tested it by playing with the temperature setting on a relatively cool day, but I'm not sure.

I tested the thermostat by switching the temperature setting between warm and cold: something (the compressor, I think) turns off and on, so it seems to work.

You sure it's not icing over?

Not 100% sure, but I don't see any ice when looking into the unit with a flashlight, and air flow doesn't seem affected.

OP, your has a leak too but a much worse one it seems..

I'm not sure that it was charged by the handyman. He said that he did, but performance was still inadequate. I don't remember if it was any better.

That's what it sounds like to me, the compressor could be failing. When it gets too hot it cuts out, then when the windings cool down enough it starts back up again. Can you still hear the compressor when it starts to blow warm air?

I think so. There's only on slight change in sound when it stops cooling. I hear something in addition to the fan.

Dirty coils?

I'd suggest you try cleaning the condenser coils.

Having thought about it more, crud on the coils is a definite possibility. We've had 3 times in the past two years where heavy wind and rain has blown outside water into the unit, which then drips onto the floor.

 

[Dessert Tears]

Any other suggestions?