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.
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.
