I have a Carrier Heat pump with a Honeywell digital thermostat.
Ocasionally my heat pump made clicking sound when it's running(I think the clicking is from the relay on the outside unit, but I can hear it inside too). The clicking sound is synchronized with the "Emergency Heat light" turning On and Off. The clicking goes on for 5 to 10 minutes. Or I can temporarily stop it by lower the thermostat setting. This clicking has been going on for sometime in the winter. During summer months, it runs normal in cooling mode. Can someone tell me what could be wrong ? bad defrost? reversing valve? and why so?? thanks.

 

The clicking rate is about 2 per second

 

What model is the thermostat?

 

The thermostat is a Honeywell Chronotherm III
But but the problem is not the thermostat because I swaped it with a new one and the problem remains.

 

Swapping the thermostat was a good idea. It was my only bright idea. I'm not familiar with Carriers heat pumps but I'm sure someone will come by here that is.

 

I found a post on another website.... the guy had the exact same problem as I did, he had 2 HVAC contractors checked it. They both said it's a bad defrost board. They both recommend replacing the defrost sensor too. I guess that's something I could try.

 

I don't know if that would have to come from Carrier or not. I replaced one on an Armstrong unit last week and it was under $25. Good luck.