When I place my thermostat in cool setting it runs for a couple of moments with cool air. Then the emergency heat light comes on and unit blows hot air. The thermostat remains in cool setting.

Have you just replaced the thermostat or changer any wires?

I have not changed thermostat /should I?

I have not changed thermostat /should I?

No this problem could be a relay or other fault. look at the sticky notes at the begining of this list to see if there are any suggestions. Usually you need to call a profession unless you know about relays ,thermostats etc.

May have a bad thermostat or grounded wire. Remove the W1 and or W2 wire from the t-stat or fan coil and try a/c again, does the heat come on with the a/c now?(Turn power off first and tape ends off wire)