If your programmable thermostat is trying to turn on your home's electric heater but the blower motor will not come on, then the electrical capacitor has very likely failed. The good news is that you can easily fix this problem yourself with only an insulated handle screwdriver and about a half-hour's time.
Symptoms of a Failed Blower Motor Capacitor
The function of the capacitor on the blower motor in your HVAC system is to turn on the blower motor when the furnace is heating air to be distributed within your home. When the capacitor begins to fail, it will make a humming noise and will not have enough electrical current to make the blower motor's cage turn. If you can manually turn the cage and start it spinning, then the capacitor is bad and needs to be replaced.
Follow these steps to replace the faulty capacitor for your furnace's blower motor (you can buy a new capacitor at a home improvement store):
Turn off the power to the HVAC system at the power panel. Since your heater runs on 220-volt current and has a hard-wired connection into your home's power panel, you must turn off the power to protect your safety while you make this repair. If you do not, you could be electrocuted.
Locate the capacitor for the blower motor on the front of the furnace. When you remove the cover on your furnace, you will see a cylindrical part that is a couple of inches long. This cylinder is the capacitor that you are going to change. You will notice it has two wires connected to the ports at the top.
Remove the old capacitor from the blower motor's side. Using an insulated handle screwdriver, remove the electrical wires from the faulty capacitor. While you remove the part, you need to hold it only on the end away from the wire connections. The capacitor stores electrical current and needs to be discharged safely before you can handle the port area with your bare hands.
Discharge the charge from the capacitor. Using your insulated screwdriver, hold the handle without touching the metal and place the metal part of the screwdriver across both ports on the top of the capacitor. This will make a complete circuit and discharge the current from the capacitor so you can handle and dispose of it safely.
Install the new capacitor. Place the wires on the new capacitor. The order of the wires does not matter as both ports on the capacitor are the same.
Test your home's HVAC system. Finally, once you have replaced the capacitor and turn back on the power, then you should turn on the thermostat and ensure that your blower motor is once again coming on when the thermostat asks it to. If not, then you should contact a professional heating contractor to perform additional troubleshooting.