A. Check for a dirty filter, is the power switch on, is the circuit breaker tripped, is the thermostat set to heat or cool and the proper temperature?

A. Gas or Oil Furnaces are rated in AFUE (Annual Fuel Utilization Efficiency), Heat Pumps in HPSF (Heating Season Performance Factor) and Air Conditioners in SEER (Seasonal Energy Efficiency Rating). With gas furnaces you should buy a model with a 92% rating if you run the blower continuously for better air filtration as it has a more efficient blower. However, if you allow the air to turn off when not heating, a 95% model will save you energy in the long run. On the A/C side it has more to do with comfort as you get to the higher SEER ratings in our climate. The base A/C is a 13 SEER for each point you go higher it uses about 10% less energy to run.