No heat from Carrier Heat pump

Old 01-18-20, 03:14 PM
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No heat from Carrier Heat pump

A couple of years ago I began to have issues with what I assumed to be my Carrier Infinity Thermostat. The heat would run all day and when I tried to change the settings on the thermostat, it would go haywire with the numbers and days of the week just running and running. I could not afford for someone to fix my system so I basically just left it off, used space heaters in the winter and fans in the summer, and manually turned the system on and off to warm up or cool down the house when the fans and heaters weren’t enough. This summer, the air conditioner seemed to be working properly, automatically coming on and turning off (the thermostat still was out of whack). But when I tried to turn the heat on this fall, nothing would come on. I decided to buy a new thermostat from Home Depot to try to install myself, but still nothing is happening. I have a Carrier heat pump but am unsure if I have Aux heat or not. The wires in the Carrier infinity thermostat are different than most of the posting about thermostats that I have read. Only 4 wires were connected. The green wire was in A, the yellow wire in B, the white wire in C, and the red wire in D. The new thermostat is Honeywell RTH2510/RTH2410. I connected the A to G, B to Y, C to W, and D to R and set the system for Heat pump but nothing is happening. The instructions say that heat pumps should have B or O connected but my old system did not have B or O. Any help would be greatly appreciated!
Old 01-18-20, 05:30 PM
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Welcome to the forums.

You have a Carrier communicating thermostat. It uses only a few wires to send all commands to the system. As it stands.... you cannot connect a generic thermostat to it. It may have an EIM (interface module) at the air handler that may be able to be removed/bypassed in order to connect a regular thermostat. You'll need to investigate around the air handler.

A model number of the air handler would be needed.
A model number off the outside condenser would be helpful.
Pictures of the system as are always helpful....... How-to-insert-pictures.
Old 01-21-20, 07:46 PM
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The Carrier Infinity heat pump may be able to work with a non communicating thermostat but you will need to move around some wires at the air handler and outdoor unit. You may also need to pull more wire to the indoor and to the outdoor units.

A and B are communicating terminals. They are not going to connect to a non communicating thermostat.

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