Hello all, I have a Trane central air unit with a heat pump, that is about years old. Recently, I have noticed that the unit sometimes cycles on and off 4-5 times before starting. It will run about a second and shut off for about a second. (I am talking about hearing it blow from the vents, it happens too quick for me to run outside and see what the unit is doing out there) I tried replacing the themostat, but noticed early this morning that it did it again. As stated above, it doesn't do it every time the unit tries to kick of, but does it frequently. Any advice on the matter will be deeply appreciated.

Make sure the hole where the wires come through the wall to the thermostat is sealed or caulked. Air movement through that hole can cause problems. See if your thermostat has a anticipator circuit for the A/C. If so open it up a bit to help prevent short cycling.

It could also be a component causing this problem. If it does it intermittent check all wiring for any loose wires on all components etc.