Test your HVAC and Thermostat

Otherwise known as “Don’t buy a Lux Thermostat”

2021 05 25 09.42.45
No Thermostat is better than a Lux Thermostat

It’s getting warm enough that we finally kicked on air conditioning today. The problem was the air conditioning wasn’t having anything of that nonsense. So does our air conditioner compressor need serviced or is this yet another nightmare in the continuing LUX Thermostat saga?

So before I called for a repair, I wanted to know whether or not my compressor actually worked. Fortunately I found this handy article: https://www.hunker.com/13415771/how-to-bypass-a-thermostat-to-test-it (Thank you Kenneth!) that explains what all of the wires do and which ones to connect together to get your heat or your air conditioning to kick on.

So all I had to do was connect the red and yellow wires and my air conditioning started right up. Warning: don’t try this at home, unless you’re really, really sure your red and yellow wires are really your red and yellow wires.

Apparently, it’s not too terribly uncommon that wires of random colors get used. So the best way to confirm that your red and yellow wires are indeed your red and yellow wires is to see if they are attached to the R (or RH) and Y contacts on your existing thermostat. Even better, see if you can confirm that the proper wire colors are attached inside of your furnace.

Assuming that your wires are straight, here’s the main combinations:

  • Red & Yellow: Air Conditioning
  • Red & White: Heat
  • Red & Green: Central Fan
  • Any other combinations: Go buy some car fuses.
APR lg

Seriously, there are car fuses inside your furnace. If you touch the wrong wires together you’ll freak yourself out thinking you’ve killed your furnace when you’ve only killed the fuse. Furnaces are generally 3 or 5 amp fuses. Trust me, based on multiple personal experiences: Don’t short the thermostat wires when your furnace is on.

I’m happy to report that my compressor is fine and it’s currently blowing 53 degree air. So, thanks, LUX for more wasted time and frustration. These were really impressive thermostats until the “glorious” LUX 2.0 (aka LUX SUX) came out. John says it best: “WARNING: DO NOT BUY-ONLY READ REVIEWS 10-2020 OR LATER!

6/3/2022 Finally got around to replacing the stupid Lux thermostat. Trying a Wyze thermostat now. I’m slightly scared because they seem to have just gone through a new app update that is not generating enthusiasm. I hope it’s not the catastrophe that Lux 2.0 is. (Has there ever been a class action lawsuit against Lux?)

When we installed the Wyze thermostat, it started clicking. Fortunately we found the answer here:

So far most clicking sound problems that I’ve helped people troubleshoot have been bad or intermittent hot or common. check your wires to make sure they haven’t stress fatigued by turning off the power and pulling on the copper part while holding the insulation back a ways. Don’t pull super hard, just check to make sure they are not broken under the insulation.


So, probably in all of the disconnecting and reconnecting we did with the Lux thermostat, we must have broken the blue/common wire which was totally freaking out the Wyze thermostat.

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