Troubleshooting if a Thermostat is BAD: Explained!

All right this video is about how to tell if your 
thermostat is bad First thing you're going to want to do   is you're going to want to pull apart right 
here on your thermostat, open up the face all right   So I'm assuming that this LCD display will be lit 
up but we're not able to turn the fan on we're not able to   turn the heat on we're not able to turn the cooling on So you have red as your 24 to 28 volt power wire coming in   and then it goes back out either the 
white, yellow or a green wire depending on what you're telling it to do   the thermostat when telling 
the fan to turn on the 24 volts will be coming in the red   and and coming back out the G if it was 
coming in as red and going back out as the Y   that will be for a cooling, 24 volts coming in for 
red and if we turn the heat on it will come back   out the white wire and go to the furnace control 
board in order to tell it what the to do Okay so these are your signal wires so what we really 
need to do here is to determine if if the fan is going to turn on  we could take the display 
and the control board out of play a couple of different ways   You could take a thermostat wire 
like this, strip both ends and you could use as a jumper all right so  You can pull this faceplate 
off, this 24 volt faceplate while the furnace is on or the air handler is on  all right it's 24 
volts and all this is is signal wires the only way   that you could short out the thermostat wires 
will be by connecting the red and the blue wire   together that would short out the transformer and 
the furnace or or short out the fuse protecting   the transformer in the furnace all right so 
just leave them alone and if you don't even   have a common because you have batteries in your 
thermostat you know then then there's nothing to   short it out against right there unless you hit a 
common somewhere else.

All right we're ground so   You have 24 volts in the R okay you're going to 
connect that over to the G if when you do this and   you put you know pressure on it you want to keep 
make sure your fingers are safe and not touching   the electrodes there but if that turns the fan on 
then you know that the this faceplate is bad okay   and that the terminal terminal board back here is 
still good all right but if you want to take this   out of play we could we go about that as well if 
you didn't have a jumper like this you could even   take some pair of needlenose okay you could go 
from here to here all right and jump it out that way you could jump it out with set of jumper wires 
you know you could you could push this in here and   this in here just make sure that they're smaller 
than the opening okay and that would jump it out   as well all right in this case since we're going 
to pull the wires out we're going to actually take   this out of flight I would suggest that go ahead 
and turn your furnace or air handling off right   before you go touching any of these wires and 
pulling them out turn the furnace off confirm   that it's off then you're going to go ahead 
and turn your screw counterclockwise and pull   your red wire out   I always like to start with the 
green wire you know cause it just turns the fan on If you were to try to jump the Y and the red 
out then there would be no 5 minute on delay to keep the compressor safe so if you were to turn 
these on and the compressor turned on and then   you turn the compressor off and then immediately 
turn it back on again that will do damage to the   compressor and you don't want to do that all right 
so in in the thermostat here there's a 5 minute on delay between when you've turned the compressor 
off and you turn it back on again just just to keep the compressor safe  all right but anyway 
so if you just connect the red and the G wires together   we can connect them with alligator 
clips or if you don't have that just a simple wire nut will do   You can connect it like this 
or you could wire knock them together like this All right now you go ahead and turn your furnace 
back on.

pexels photo 5835359

Can you see that? Turn your furnace back on and see if the fan turns on all right if it does not 
turn on then your problems back at your furnace all right So that's how you would do all right 
if you wanted to turn the power back off to your   furnace and wire nut the R and the white wire 
together to see if your heat will turn on the sequence of operation of your heat will turn on 
then you can do that too I would just be careful with  make sure your furnace is off first of all 
I will be careful with maybe touching this to the yellow wire  because you don't want to do damage 
to that compressor because it's going to have   low pressure refrigerant on one side high pressure 
refrigerant on the other side and it's going to   have a heck of a time trying to turn back on if 
it hasn't been given a chance to equalize those   refrigerants so the simplest thing is to just 
connect the red and the G together all right so   that's it that's how you tell if your thermostat 
is bad if that fan does tunnel come on then you   just need to replace this thermostat right, but
as I've said before just make sure your power's off   while you're doing it all right.

Okay hope you had a good 
time and see you next time at ACSERVICETECH.COM.

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