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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22633
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a trane gas heat/air conditioner combo unit outside.

Customer Question

I have a trane gas heat/air conditioner combo unit outside. I have a hunter programmable thermostat. I have five wires out of the wall actually 6 but the brown wire is cut down so wasn't used. But 5 wires a green, white, red, blue, yellow. The inside of the thermostat I have Y1, W/b, Y/0, Rh, RC, and G. Which wires go to what. I have had some gentleman my wife called come in and keeps switching everything.
Submitted: 7 years ago.
Category: HVAC
Expert:  BillyHvac replied 7 years ago.

First the red wire goes to Rc/Rch should have a jumper

white wire goes to w

yellow wire to y1

green wire to g


if the old thermostat used a C terminal tape off the blue and do not use. I am available for follow up

Customer: replied 7 years ago.
I have it looked like you said. Now when I flip to heat. I hear the big trane unit come on outside. No air flow through the floor vent though. When I go to cool the big trane unit comes on and there is air flow. Both of these modes without the fan in on but in auto. If I go to heat the big trane unit comes on and then flip the fan to on instead of auto then I get flow but cold air. Right now I took the blue wire and taped it up even though it was stripped back as if it was used. Not trying to be difficult but the fix it man who kept flipping the wires changed the thermostat to this hunter thing so not really sure if the blue wire was used or not.
Expert:  BillyHvac replied 7 years ago.
the blower for heat is activated by the unit and not the thermostat. It sounds as though the heat relay in the unit has been compromised. As a temporary fix jump the W and the G together. Then when unit starts it will turn on the blower at the same time as the heat. Difference will be the exchanger will not be warm when blower starts at first
Customer: replied 7 years ago.
Now it is acting just like it did before it came on and the fan came on with it but the air is still cold. This is a big combo unit and then there is another little unit next to it outside. It does not come on. This is for the downstairs. I have another heater I believe in the attic for the second floor and that heat works fine. Is the small unit outside a air conditioner for the second floor or something to do with the heat for the downstairs. Also would this unit outside be considered a heat pump and if so a single stage or multistage. Does it maybe have a pilot light for the gas that is fed into it or something.
Expert:  BillyHvac replied 7 years ago.
I need the model number for the unit
Customer: replied 7 years ago.
The numbers off of the unit are Model YCC018F1L0BA Serial G38158886. Gas fed 208-230 VAC. 24V control or something to that effect.
Expert:  BillyHvac replied 7 years ago.
do you mind taking the top of the thermostat off for a test?
Customer: replied 7 years ago.
Are you speaking of the thermostat in the house or one at the unit.
Expert:  BillyHvac replied 7 years ago.
House...remove top of thermostat and touch the R terminal and the G terminal at the same time with a paper clip or wire so they are jumped together. Tell m if fan comes on.
Customer: replied 7 years ago.
yes it comes on.
Expert:  BillyHvac replied 7 years ago.
Now remove the white wire, the red wire and the green wire from the thermostat and twist them together so they are all touching. Let me know if fan comes on and heat kicks on
Customer: replied 7 years ago.
Yeah it came on and the fan. But still not hot.
Expert:  BillyHvac replied 7 years ago.
is theheat section running?
Customer: replied 7 years ago.
yeah I hear the outside unit come on and the fan comes on but the air seems to be full flow and not hot.
Expert:  BillyHvac replied 7 years ago.
now unhook the green wire and tell me what happens
Customer: replied 7 years ago.
The fan goes off unit still on outside but very low air flow and still cold.
Expert:  BillyHvac replied 7 years ago.
Last thing I will have you do.....go to the unit and follow the thermostat wire into the electrical section. Tell me what terminals the colors go to.
Customer: replied 7 years ago.
Ok. Maybe a little bit for this one as it is raining quite hard.
Expert:  BillyHvac replied 7 years ago.
I can leave this open until you are ready