Hey everybody, I hope you can help me with the problem I am having converting my old Trane Mercury thermostat model #3AAT80A1A1 to a Honeywell Digital thermostat model #RTH7600B. I currently have a multi-stage heat pump system.

The Trane has wires that are connected to O, R, T, G, Y, B, W and the W wire is also connected to X2.

The Honeywell has locations for C, G, Y, O/B, RC, R, AUX, E, L (for heat pump installation)
The Honeywell also has locations for RC, R, W, Y, G, C, Y2, W2 (for conventional installation)

I have accounted for all the wires from the old system to the new system, except for the T wire. This is according to the instruction manual that accompanied the new thermostat.

Thanks in advance for helping me solve my problem.

v/r
reespy

T will probably go to l, what color is it?

Quote:

---

Originally Posted by Joshdta

t will probally go to l, what color is it?

---

It is green, we did eventually hook it to L, the system seems to be running properly, except it is not cooling.

Do you have a jumper between rh and rc?

Quote:

---

Originally Posted by Joshdta

do you have a jumper between rh and rc?

---

There is a jumper between RC and R on the Honeywell, but there is no RH

OK by not cooling do you mean it will not run in cooling mode or it is running but blowing hot air?

Quote:

---

Originally Posted by Joshdta

ok by not cooling do you mean it will not run in cooling mode or it is running but blowing hot air?

---

We figured out why it was running, but blowing hot air... we didn't program the thermostat to reflect that we had it hooked to a heat pump. It is cooling now, if I have anymore problems I will post another question. Thanks for your help in resolving this matter.

T is for a cooling anticipator in the thermostat. It is hooked to a thermistor in the outdoor unit. This functin is not needed and should be deleeted when replacing with a modern programmable thermostat.