Trane Blower makes starting type noises after cycle is finished.

[markmm]

This Trane unit (TWH024B140A0) is 20 years old, and 1 year ago the blower started making momentary start noises for half a second every 30 seconds and this goes on for as long as 30 minutes after the unit is through with an a/c cycle. The other day, the power was off for a couple hours, and when the power came back on, I heard the unit start this noise up even though it had not been running (a/c only unit). I turned it off at the breaker. I got up in the attic today and ran the unit, and could not make it misbehave.
In the past I have even disconnected the thermostat but the noise continued.
Capacitor, relay and motor look 100%. I was going to change the capacitor first, since it is so cheap. Am I missing something here? I have asked a couple repair people and just got a stange look.

[paul52446m]

This Trane unit (TWH024B140A0) is 20 years old, and 1 year ago the blower started making momentary start noises for half a second every 30 seconds and this goes on for as long as 30 minutes after the unit is through with an a/c cycle. The other day, the power was off for a couple hours, and when the power came back on, I heard the unit start this noise up even though it had not been running (a/c only unit). I turned it off at the breaker. I got up in the attic today and ran the unit, and could not make it misbehave.
In the past I have even disconnected the thermostat but the noise continued.
Capacitor, relay and motor look 100%. I was going to change the capacitor first, since it is so cheap. Am I missing something here? I have asked a couple repair people and just got a stange look.

Since this is a ac only, i am guessing that it is a blower coil air handler 240 volts? There would be one 120volt leg going to the motor all the time. I am guessing that the motor relay is getting bad contacts, and points are lose and
keep bleeding a little power through to the motor and then kicks back out. It would only do this in the off time. This is not a common thing. i would try changing the blower relay... Paul

[markmm]

Thanks, Blower is 240v - should have mentioned that. I had another relay but when I went to install it the existing relay had a circuit board clipped onto one side and the relay I had would not work that way. Will try your suggestion and get a replacement.