coil squeeling in heat mode outside unit 13 seer goodman heatpump inside coil is mortex coil for mobilehome ahu. cold outside when unit comes on makes loud whistler sound maybe for 10 to30 seconds. loud enough to wake you up.installed 1/2008 changed coil out 2/08 still have same problem. system was bought as match set coil TXV no orfice. install alot of the systems no problems like this if you can help it would be ablidge!