Author Topic: Override window air conditioner not working  (Read 1082 times)

Offline philhelm

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Override window air conditioner not working
« on: July 17, 2019, 05:34:42 pm »
Ok so ive read a few posts on this and I thought i understood how top do this.. i have a frigidare 5000btu unit listed here:

https://www.amazon.com/dp/B00W..._sw_r_cp_awdb_t1_O80lDbFBZKGTS

I took off the cover and moved the copper temperature sensor out. I bought a night light (replaced the tiny bulb with a larger one that was hot the minute i plugged it in) put an incandescent bulb in, created a "hot box" for the sensor And the light, and cranked it up. I can't seem to get the temp below 62/63. What am i doing wrong?

Offline Bob357

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Re: Override window air conditioner not working
« Reply #1 on: July 17, 2019, 06:25:06 pm »
A 5000 BTU Air Conditioner is adequate for cooling a 100 - 150 sq. ft. room to a comfortable temperature. Reasonable performance can only be expected within the normal temperature range of the unit and excessive sun load or other heat will hinder performance.

 The temperature you cite, 62 to 63 degrees, is the very low end of what I would expect the unit you have to cool to under ideal conditions. Tricking the sensor only keeps the unit running. It doesn't enhance its performance. Understand that an AC unit does not create cold air. It transfers heat and can only transfer the amount it was designed to.

Depending on what temperature you want to maintain you will definitely need a much higher capacity unit, possibly additional insulation and an external temperature controller that will handle the startup load of the unit.
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Offline philhelm

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Re: Override window air conditioner not working
« Reply #2 on: July 18, 2019, 01:02:59 am »
Thanks Bob.  Do you have an ac unit you could recommend that i could get down to 35 degrees F ?

Offline Bob357

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Re: Override window air conditioner not working
« Reply #3 on: July 18, 2019, 10:22:46 am »
A window AC unit isn't designed for that kind of temperature, assuming you're talking about cooling an area of any size. That's something you'd need to talk to a commercial refrigeration professional about. While I have a lot of experience in mobile HVAC, I'm lost when it comes to commercial refrigeration. Theory is the same, but the dynamics aren't.
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Offline BrewBama

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Override window air conditioner not working
« Reply #4 on: July 18, 2019, 11:59:08 am »
Have you seen this: https://www.storeitcold.com/how-it-works/


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Offline Robert

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Re: Override window air conditioner not working
« Reply #5 on: July 18, 2019, 02:19:11 pm »
The way my HVAC guy explained it to me in layman's terms is this.  On an air conditioner,  the refrigerant should be boiling somewhere around 50°F, maybe just below.   So the air coming off the system, if everything is working right, should be within 10° above that.  That's the lowest temperature any air is ever going to get with this system; you can't cool air below the temperature of the refrigerant, or even to that temperature, since physics just won't let us have 100% efficiency.   That's why AC systems are rated not in BTU but cubic feet, the amount of air they can move in a given time.  Since you can't add a small amount of super cold air to cool a space (like putting an ice cube in a glass,) being limited to air somewhere approaching 60°F, you need to keep turning over the entire volume of air in the space you are cooling.  So there's a limit to the lowest theoretical ambient temperature a given unit can achieve, and a limit to how much space it can achieve that in.  Any product or hack claiming to beat this seems too good to be true.   An air conditioner is just not a refrigerator.  Bob, do I have that right?
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Offline Visor

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Re: Override window air conditioner not working
« Reply #6 on: July 18, 2019, 04:57:53 pm »
   Rob, I think your explanation isn't entirely correct. Traditional air conditioners certainly can cool air to well below 60* under the right [or wrong] conditions, if they couldn't they would never be able to freeze up the evap. coils, and I've seen enough blocks of ice with an evap coil inside to know it happens more often than one would think.
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Offline Robert

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Re: Override window air conditioner not working
« Reply #7 on: July 18, 2019, 05:05:24 pm »
Thanks for clarifying.  Guess the explanation I got was regarding what to expect from a properly functioning system, which the OP hopes not to have.
Rob Stein
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Offline Visor

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Re: Override window air conditioner not working
« Reply #8 on: July 18, 2019, 06:02:48 pm »
   Well put, my 1st question for philhelm is how large of a volume are you trying to cool? Is that 62/63 degrees the discharge air temp exiting the unit or the temp of the space you are trying to cool? I've seen brewery cool rooms 400 sq. ft. or larger that were held well below 50* with 5,000 bTU air conditioners and a coolbot, but they insulated almost to the level of a walk-in cooler and rooms of >100 ft that were kept in the low 30's, again with only 5,000 bTU's. Those were in eastern Tennessee in the summer with very high humidity. I don't know where you're located or what your humidity levels are like, but the more humid it is, the more latent load you're placing on the AC, thereby reducing the amount of sensible load [actual air temp] you have bTU's left to deal with. 
I spent most of my money on beer, tools and guns, the rest I foolishly squandered on stupid stuff!

Offline narvin

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Re: Override window air conditioner not working
« Reply #9 on: April 02, 2021, 11:43:31 pm »
I also had such situation and it scared me a lot.

It's going to be okay. Just remember, you aren't real.

Offline erockrph

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Re: Override window air conditioner not working
« Reply #10 on: April 03, 2021, 10:41:44 am »
I also had such situation and it scared me a lot.

It's going to be okay. Just remember, you aren't real.
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Offline weazletoe

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Re: Override window air conditioner not working
« Reply #11 on: July 25, 2021, 12:14:04 am »
Late to the game A/C guy here. Rule of thumb is a properly charged unit should cool about 20° below ambient temp. So, say you have a window unit in your basement cooling a small fermentation room in it as I had in my old house. If the temp of your basement is 68° your fermentation room should be able to get down to 48° give or take a couple. Anything more just won't happen.
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