The Honeywell RTH230B programmable thermostat is a residential thermostat used to control the heating and cooling systems in your home. The thermostat works well under most conditions but may periodically create problems for the owner. Most problems stem from improper settings on the thermostat, which cause the heating or cooling systems to work improperly. You can troubleshoot the Honeywell RTH230B and fix most problems without the help of a service technician.
Change the batteries in the Honeywell RTH230B if it is inoperable. To change the batteries, pull off the battery cover located on the top and front of the thermostat. Remove the old batteries and dispose of them properly. Insert two new AA batteries with the positive polarity of each battery facing the left of the thermostat. Reattach the battery cover by pressing it into place. You will hear a click when the cover is secure.
Move the selector switch, located on the bottom left of the thermostat, to the "Heat" or "Cool" position if your heating or cooling system is not turning on. The thermostat will not operate either system if the switch is in the "Off" position.
Wait at least five minutes for the air conditioning unit to turn on if the thermostat is in "Cool" mode. The delay is a safety measure intended to protect the compressor from damage.
Slide the "Fan" switch, found on the bottom of the thermostat to the right of the selector switch, to the "Auto" position if the fan does not turn off. The fan will run continuously if placed in the "On" position.
Reprogram the thermostat for different periods during the day if you find the thermostat is changing the temperature setting by itself, for example, if you set the thermostat to 21.1 degrees C and at a certain time each day it changes to 18.3 degrees C. This happens when a previously programmed temperature setting overrides your current temperature setting. The Honeywell RTH230B allows for up to four different time periods during the day: wake, leave, return and sleep. To program each time period, press the "PGM" button. Press the "Day" button once for weekdays and twice for the weekend and hold the button for seven days. Use the up and down arrow buttons to change the start time. Move the selector switch to "Heat" or "Cool" depending on your needs and press the "P#" button. Change the temperature with the up and down arrow buttons. Move the selector switch to the opposite position and set the temperature. Press the "P#" button to move to the next period and repeat this step to set the temperature for the next period of time. Press "Exit" when finished.