Latest Discussions : Electrical & Lighting


10:39AM | 06/03/04
Member Since: 06/02/04
4 lifetime posts
if so, how? can you help?


10:48AM | 06/03/04
Member Since: 11/11/02
2267 lifetime posts
** is it possible to add a thermostat control to a window a/c unit? **

It should have one already, why would you want to add another??

Dan O.

The Appliance Information Site



10:51AM | 06/03/04
Member Since: 06/02/04
4 lifetime posts
the window a/c i have does not have thermostat


04:00PM | 06/03/04
Member Since: 11/11/02
2267 lifetime posts
I've never seen a window or wall air conditioner without a thermostat but if that's really the case one should be able to be added provided:

1. There is room on the unit for one to be installed.

2. You can figure out how to modify its wiring to accept one.

You can see two 'universal' window air conditioner thermostats at the following link. I don't know what you'll use for a knob or the temperature dial calibration marks. I do not believe they come with them.

Air Conditioner Thermostats


Dan O.

The Appliance Information Site



04:49PM | 06/03/04
Member Since: 06/02/04
4 lifetime posts
i meant if it is possible to either replace the dial thermostat with or connect to a electronic thermostat so the a/c can be turned on and off automatically, similar to the "economy mode" of some latest models. thanks


01:25PM | 06/04/04
Member Since: 11/11/02
2267 lifetime posts
Well that's certainly different than not having a thermostat to begin with. Unfortunately, I have never seen such a retrofit kit available and doubt there is such a thing.

Whether you can design something which would work is anyone's guess, you would *not* be able to use a low voltage central A/C thermostat without a bunch of relays, etc. to use to cycle the units components.

IMO if you want an air conditioner with a digital temperature control you'll likely have to buy one with that feature already on it.

Dan O.


03:27PM | 06/04/04
Member Since: 07/01/03
549 lifetime posts
We built a wine cellar and used a thermostat to control the electric power to a small AC unit that is used to maintain a contant temperature. This application is used in greenhouses, whole house fans and lots of other applications, and it costs less than $50.

Take a look at the inexpensive options at this link:

These thermostats work by turning on and shutting off the power in response to a set temperature range. It does not use a low voltage system to kick on a relay like conventional HVAC thermostats.


10:42AM | 06/05/04
Member Since: 11/11/02
2267 lifetime posts
** Take a look at the inexpensive options at this link: **

Nice. The "Thermostatic Outlets" look interesting and at 15 amps should be able to handle most window a/c's although switching on the *whole* a/c (motor and compressor together) at the same time will draw more amperage initially than is normally done but in most cases shouldn't be a problem.

The Thermostatic Outlets might be more useful though with a dehumidifier to prevent freeze up as they don't usually have thermostats.

Maybe one of the others will work for what the OP has in mind? They seem reasonably priced.

Dan O.


05:37AM | 06/19/15
you fools, here it is


07:26AM | 06/19/15
Now that's what I call "nice" LOL.


06:01PM | 06/04/16
Yes. There are a few ways to do it but you will need some electrical skills. Window units have a turn dial setting for warmer/colder that is a simple thermostat. Inside the AC for the turn dial is a relay connected to a thermistor that measures the air temp coming into the unit. I unhooked and removed this relay and replaced it with a 30amp simple relay. for my situation, the new relay was controlled by 24 volts AC. I also had to buy a transformer to provide the 24VAC. I then run the wires that control the relay to my wall thermostat mounted in the middle of the room. Now I turn the ac on the cool mode on the fan setting that I want. Then I turn the digital wall thermostat from off to cool mode and it actuates the relay, turning on the compressor. The compressor will run until the room temp reaches the setting on the wall thermostat. This creates a more accurate room temperature. I also have a squirrel cage fan in the room to spread the cold air from the ac across the room.


08:59PM | 06/04/16
All that?? Why not just buy the 36 dollar unit? LOL. Your way the fan keeps running instead of turning the whole unit on and off to save energy. Asinine.


01:05AM | 07/23/17
I know this is an old post but for those interested in doing this it is very possible and pretty easy. Here is a link to the thermostat controller I use.
You can also do fancier stuff with a Arduino or raspberry pi board, some temp sensors and some relays switches. Good luck all.

-The Mad Tech


08:02PM | 04/27/18

I've been using this and highly recommend.


10:07PM | 01/23/19
what about 220v system ?


03:02PM | 08/13/19
For 220 vac applications:
White-Rodgers 90-T40M1 hooked to neutral and hot1 to provide 24 VAC control circuit, then white Rodgers 90-380 dual pole, dual throw relay. Run both hots through the 90-380 and use the thermostat to close the circuit on the 24 VAC side.
If it's a smart thermostat, then connect R to the output side of the transformer, Y to the relay.
C connects to the other side of the relay to ground the thermostat.

There are prepackaged variants available as well, they're all over amazon


02:32PM | 10/01/19
I know this is an old post, but along the same lines, can some kind of wall thermostat be added to control an old PTAC unit (the kind that hotels often have). This is what is in my condo and no matter if I want heat or ac/ I have to go over and manually turn it on or off each time I want it to run or not run.


01:22AM | 04/25/20
Yes you can look up thermostat plug ins, you plug in ac leave it on always and the thermostat turns on when it gets to whatever the temp is set at. Then turns off when it's cold enough. It's really simple and you can get them relatively cheap on amazon.


04:10PM | 07/21/20
I have a 220 window a/c that cools the entire house. Is there somehow to add this and have the thermostat in another room? the room where ac is is generally 60 F while the rooms are 72 F. I am trying to get something to shut it off when bedrooms are 73 F so i don't have to keep checking when to manually turn on and off.


04:21PM | 05/03/21
I want to use my window air conditioner for a cooler

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