AC issues

JJWise

Eight Pointer
Let me start by saying that we rent the place we live so I’m not necessarily looking for how to fix anything, but there might be a simple step that I’m missing.

We have a AC/Heat Pump and about a month ago I had to change the batteries in the thermostat. Since then, about once a week it will start blowing warm air while on the cool setting and will not stop blowing hot air even after it has surpassed the max temperature we have programmed on the thermostat. It happens during the warmest part of the day, and if you turn the system off for a few hours it works fine again when turned on and will continue working correctly for about a week. We leave it on the “auto” setting so that it will cool and heat as needed. Is there something on the thermostat I need to do differently or is something broken? Thanks for the help
 

Mechanic Bob

Eight Pointer
Is your condenser fan working? Could be as simple as the Capacitor not working. (Life of some them is 5 -8 years)
 

Mechanic Bob

Eight Pointer
Okay. do you have the thermostat instructions or go on line and get the instructions. There is a setting that controls the heat pump to supply "Heat at the Heat Setting" and "Cold at the Cold Setting".
When you changed the batteries, it may have reverted back to the opposite operation. I had this happen to me when I first installed a programmable thermostat.
 

JJWise

Eight Pointer
I’m mainly a commercial tech but the 4-5 times I’ve seen this issue the problem has been a switch known as the sequencer. What brand unit?
The thermostat is a Honeywell, the AC unit is a Trane. The thermostat has been in the house the whole time we’ve lived here and the AC unit was replaced in 2017. The issue has changed now though, both heat and cool setting will blow hot air. The unit recognizes when the temperature inside the house gets outside of the normal range, but when the cool setting kicks on it blows warm.
 
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