We recently entered into a time of year when the thermostat will not turn the system on as frequently as it normally does in the hotter times of the summer. The system will run an cool for a while and then shuts off when the house reaches the set temperature. The system will sit in the off state for quite some time. After sitting like this, when the system first comes back on, I hear a rather loud grinding/jet like noise sound which appears to be coming from the area of the air handler. The sounds lasts for a few seconds and then stops. The system apears to cool normally after this noise occurs. The sound is a little hard to describe but it almost sounds like a jet plane flying over the house at a high altitude. The sound does not occur every time but when it does it happens after the system has been idle for an extended period of time.
A few days ago, I had my air conditioner repair company out to check the system. Of course we could not get the system to make the noise while the repair technician was present. He checked the system over, doing all of the normal things that are checked during a system tune-up. He could not find anything wrong. The sound still persists on an intermittent basis. What could this sound be and is it cause for