Author Topic: Room AC control by-pass  (Read 1122 times)

Offline davidmoser

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Room AC control by-pass
« on: March 13, 2017, 06:46:51 PM »
I would like to by-pass the controller for a room AC (Kenmore) and use an external controller similar to a Johnson.   Any help would be appreciated.


Offline Stevie

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Re: Room AC control by-pass
« Reply #2 on: March 13, 2017, 07:13:31 PM »
Coolbot. Not cheap, but worth it.

https://www.storeitcold.com

Offline Joe Sr.

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Re: Room AC control by-pass
« Reply #3 on: March 13, 2017, 08:24:59 PM »
For my cool room, I pulled the temperature sensor out through the front of the A/C and have it fed into an insulated can that has a night light inside of it as a heat source.  This makes the A/C believe it is always warm in the room.  The insulated can and the Johnson controller run on a timer so that the A/C shuts down every two hours at a minimum (concerned about freezing the coil).

I can maintain summertime temps into the 40s, though I rarely take it below 60 these days.  It's really more for wine, but also works as a large fermentation chamber.

The only significant cost was the Johnson controller.  If I did it again, I'd use an inkbird or an STC-1000 (same basic thing, but C readout).
It's all in the reflexes. - Jack Burton

Offline davidmoser

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Re: Room AC control by-pass
« Reply #4 on: March 14, 2017, 02:04:12 PM »
Thanks for your help/suggestions.  I currently have a STC-1000 controller for the area.  I am considering Stevie's suggestion but was hoping for a way to bypass the internal AC controller to make it run when the STC-1000 supplied power.  Any info on the bypass?

Offline Joe Sr.

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Re: Room AC control by-pass
« Reply #5 on: March 14, 2017, 03:05:07 PM »
I think that the bypass will depend on the model of the A/C.  When I researched this a few years ago, I found it simpler just to trick the internal A/C temp controller by heating it, rather than bypassing the controls electronically.  So, basically, I can't help.  Sorry!

Mine works functionally as you desire, it's just not as elegant.  But it's also easily reversible, which was nice when I went to larger A/C.
It's all in the reflexes. - Jack Burton

Offline Stevie

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Re: Room AC control by-pass
« Reply #6 on: March 14, 2017, 03:26:31 PM »
I think that the bypass will depend on the model of the A/C.  When I researched this a few years ago, I found it simpler just to trick the internal A/C temp controller by heating it, rather than bypassing the controls electronically.  So, basically, I can't help.  Sorry!

Mine works functionally as you desire, it's just not as elegant.  But it's also easily reversible, which was nice when I went to larger A/C.
This is the basic idea on how the coolbot functions but it also has some protections built in to prevent freezing.

Offline Joe Sr.

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Re: Room AC control by-pass
« Reply #7 on: March 14, 2017, 03:28:50 PM »
I think that the bypass will depend on the model of the A/C.  When I researched this a few years ago, I found it simpler just to trick the internal A/C temp controller by heating it, rather than bypassing the controls electronically.  So, basically, I can't help.  Sorry!

Mine works functionally as you desire, it's just not as elegant.  But it's also easily reversible, which was nice when I went to larger A/C.
This is the basic idea on how the coolbot functions but it also has some protections built in to prevent freezing.

My Rube Goldberg approach was to put the whole gig on a timer to give any potential freeze up time to defrost.
It's all in the reflexes. - Jack Burton

Offline weazletoe

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Re: Room AC control by-pass
« Reply #8 on: March 14, 2017, 03:59:37 PM »
Any info on the bypass?

Take the leads to the internal t-stat and wire nut them together. This will make it run constant so that you cn turn it on and off with your STC-1000.
A man works hard all week, so he doesn't have to wear pants all weekend.

Offline davidmoser

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Re: Room AC control by-pass
« Reply #9 on: March 15, 2017, 07:28:10 PM »
Thanks all for the help. Since I only plan on using the room for temps. down to 54F I am hoping there won't be any freezing problems.  If I do the suggestions on Coolbot & and night light in a can can be tried. 

For "weazletoe", the internal "t-stat" you mention, is that the cool-side temp. sensor?

Offline chinaski

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Re: Room AC control by-pass
« Reply #10 on: March 15, 2017, 07:45:25 PM »
Any info on the bypass?

Take the leads to the internal t-stat and wire nut them together. This will make it run constant so that you cn turn it on and off with your STC-1000.
I'd be careful about powering an AC unit with the STC-1000- the STC is rated for lower power applications only.  I'm guessing an AC unit would fry it.  The coldbot was created to handle this application.

Offline weazletoe

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Re: Room AC control by-pass
« Reply #11 on: March 15, 2017, 07:47:38 PM »

For "weazletoe", the internal "t-stat" you mention, is that the cool-side temp. sensor?

Not sure what you mean by "cool side sensor". I'm just making an assumption that you have an a/c with with a mechanical dial like stat. There should be two power wire on it. One hot, going in, and one out that is hot when the stat calls for cooling. cut these two off the stat and nut the together. The A/C should run 24/7 when you do that.
A man works hard all week, so he doesn't have to wear pants all weekend.

Offline weazletoe

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Re: Room AC control by-pass
« Reply #12 on: March 15, 2017, 07:49:26 PM »
I'd be careful about powering an AC unit with the STC-1000- the STC is rated for lower power applications only.  I'm guessing an AC unit would fry it.  The coldbot was created to handle this application.

Or, you should be able to run the SSR that I linked to with the STC-1000.
A man works hard all week, so he doesn't have to wear pants all weekend.

Offline Stevie

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Re: Room AC control by-pass
« Reply #13 on: March 15, 2017, 07:52:54 PM »
I'd be careful about powering an AC unit with the STC-1000- the STC is rated for lower power applications only.  I'm guessing an AC unit would fry it.  The coldbot was created to handle this application.

Or, you should be able to run the SSR that I linked to with the STC-1000.
Exactly. The STC 1000 can be used to switch a higher amperage SSR.

Offline Joe Sr.

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Re: Room AC control by-pass
« Reply #14 on: March 15, 2017, 10:02:08 PM »

For "weazletoe", the internal "t-stat" you mention, is that the cool-side temp. sensor?

Not sure what you mean by "cool side sensor". I'm just making an assumption that you have an a/c with with a mechanical dial like stat. There should be two power wire on it. One hot, going in, and one out that is hot when the stat calls for cooling. cut these two off the stat and nut the together. The A/C should run 24/7 when you do that.

Most of the newer A/Cs that I've encountered have digital controls and no longer have the mechanical dial.  I believe it becomes much more complicated to override the sensor on these.  Maybe not.  I don't recall for sure, but it was enough of a bear that I skipped it.
It's all in the reflexes. - Jack Burton