# Is the wire in front of a window A/C called thermistor



## KarlJay (Dec 9, 2009)

I have a window A/C unit that has the wire thick wire in the front. I'm pretty sure it reads the temp and tells the unit when to kick off the compressor so it doesn't frost over or regulates the temp.

Here's what I'm doing:

I need to remove the controls (manual knob controls) and move them away from the unit.

I opened the control panel and the thermistor is connected directly to one of the controls. It's the control for temp setting. I need to figure out how to extend this and don't know if simple copper wire will work.

My understanding is that sends elec signal to the control.

I have two choices for the length, I can get away with about 18" but would prefer about 4 feet.

I was thinking I could test the voltage of the wire, cut the wire, add some length of welding rod or wire, and then test the voltage again.

It's going to a manual control, it doesn't say 60/70/80/90 deg... it's just set it and figure out what works for you, so if it's off, it's ok as long as I can get to the temp range I like.

Anyone have an idea if you can extend these things and does that make change the voltage?


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## KarlJay (Dec 9, 2009)

Ok, got some more info.

The unit I'm working with is an older one that has manual controls. The newer models have digital controls. This unit uses a direct connection of the thermistor, I see some listings for digital tuermistors so maybe that's the answer.

Does anyone know if I can replace the old style with a newer type that has wires coming out of it?


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## Thurman (Feb 9, 2009)

NO, one word answer. The copper looking thick wire in front of the evaporator on you window unit is a thermal sensor and does tell a window unit when to run and when to shut off based on the ambient air temp around the sensor. These are usually filled with a very small amount of mercury, therefore hazardous if cut open. I do not know of any way to remotely mount a thermal sensor. For instance: Most RV air conditioners use these to control the interior temperature of the RV. BUT--an RV unit that has a wall mount thermostat _does not_ have a thermal sensor built into the A/C unit which is on the roof. There are kits to change an RV A/C unit from thermal sensor to a wall-mount thermostat but they are in the $150 range less labor to change it over.


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## KarlJay (Dec 9, 2009)

Thanks Thurman! Ok, so maybe I need to see if I can get a conversion kit or maybe a wall mounted system like the one my wall furnace uses.

Another option might be to get the controls from a more modern digital unit and transfer it over. Might have to use relays because this one is a 220V 24K BTU monster.


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## AandPDan (Mar 27, 2011)

That "wire" is a capillary tube. If you cut it or it breaks it won't work.

How about jumping the connections to the temperature switch so it is always on. Then get a line voltage thermostat and use it to switch the unit on/off.


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## av-geek (Jan 15, 2012)

You would proably do good with a LUX products WIN100. It's a plug-in thermostat that looks like a light timer. Just plug the unit into the wall, then plug the AC unit into the box, set it to the desired temp, and it will start and stop the AC unit at the temperature

http://www.amazon.com/Lux-Heating-Cooling-Programmable-Thermostat/dp/B000E7NYY8


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## KarlJay (Dec 9, 2009)

av-geek said:


> You would proably do good with a LUX products WIN100. It's a plug-in thermostat that looks like a light timer. Just plug the unit into the wall, then plug the AC unit into the box, set it to the desired temp, and it will start and stop the AC unit at the temperature
> 
> http://www.amazon.com/Lux-Heating-Cooling-Programmable-Thermostat/dp/B000E7NYY8


That looks great, but it's not 220. I think there's probably a 220 version out there. I'll be looking into that.

Thanks!


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