Bryant 607ENXA42000-TP behaving oddly

[LouLamb]

I have a Bryant 607ENXA42000-TP heat pump, installed in 2015, that has recently developed an odd problem. Five service calls by the dealer/installer and multiple parts replaced have not solved. It's been maintained quarterly, and cools well. What happens is that mostly during the night, the air handler comes on (It's inside the unit, not separate), runs for about 20 seconds, then stops. Then runs, then stops. This happens randomly when the thermostat is not calling for cooling, and while the condenser/compressor are NOT running. Just the air handler cycling on and off for about 15 minutes. Thermostat is a Honeywell digital, and the fan setting is "AUTO", not "CIRCULATE". The oddest part is that I can turn the system OFF at the thermostat and the fan continues running and cycling. So far the technicians have replaced the "control board" and the fan motor itself. But they seem stumped and unable to diagnose. If anyone has seen something similar, I'd appreciate the feedback. Thanks for reading!

 

[WorthFlorida]

The thermostat controls the fan in all modes. At the thermostat, you can pull it off the base and expose the wires. You can leave it off or disconnect the green wire. The wire is what signals the fan to run. If the thermostat has a default factory reset, perform the reset. Wifi thermostats gets it time from the Honeywell server. If it is not a wifi, change the time at the thermostat to the hours when you notice the problem. Recheck all of the programming. there could be a memory corruption in the thermostat and its turning on the fan. YOu said mainly night time, it could be that during the day it is on for cooling so you may not notice it.

What is the Honeywell model? My Honeywell WIFI thermostat has a fan setting call "circulate". It will run the fan at least 35 minutes of each hour regardless for the call for heat or cool. This feature allows the fan to circulate to mix warm and cool areas of the home for better comfort. I have a two story home and when the AC is not called for, it can get fairly warm on the second floor. Check your thermostat features.

The RC (red) wire from the air handler to the thermostat is the 24v AC power. When the thermostat calls for cooling it switches this 24v to the green wire. The 24v on the green wire operates a relay on the control board that in turn operates the fan motor. In rare cases the red and green wire are shorting to each other at the thermostat or else where.

 

[Sponsor]

 

[LouLamb]

Thank you for the reply. I've done a little more diagnostic work and have eliminated thermostat corruption or incorrect setting by disconnecting it totally while the system misbehaves. Even with the t'stat pulled off the wall, the blower continued to start and stop. But, I followed the t'stat wiring and found where it runs through the outdoor heat pump housing, there was a section that looked like it was chewed by something, and that section was laying in a puddle of condensation. I dried the wiring, propped it up so it did not touch the puddle or the metal frame, and so far the problem SEEMS to be gone. I'll be watching and listening for a few weeks, and if that fixed it I'll be replacing the wiring. Thanks again for the tips, which helped me to eliminate a few possibilities!

 

[Reach4]

Bend radius in that stainless steel flex line looks tight to me.

 

[Fitter30]

If the problem comes back ask the service company to call the distributor if they have factory service or if they could contact them for more insite.