Yesterday I noticed it was getting hot in the house so I found out the air conditioner was not running. The fuse looked like it was possibly blown so I replaced that and still nothing. I then checked for power on a voltage meter and power was there. I have talked to my father and he said it was likely the thermostat, circuit board or transformer. I just read on the internet that older air conditioners(mine in about 12 years) should not be using the round thermostats they should only have digital, is this true. I have had a round honey well on for the past three years when the original went out. Is there a way to check if the thermostat is bad, also how can I find out if the circuit board or transformer is bad. Any other suggestions on what it could be?