Hope someone out there can help me before I have to kick out big bucks on this unit. I have a Trane A/C unit (outside). There is ice build up on the coils and the motor and on the outside grate. This happened when I turned the switch from cool to heat on my thermostat. Can someone out there HELP ME PLEASE??

Hope someone out there can help me before I have to kick out big bucks on this unit. I have a Trane A/C unit (outside). There is ice build up on the coils and the motor and on the outside grate. This happened when I turned the switch from cool to heat on my thermostat. Can someone out there HELP ME PLEASE????
It sounds like you have a heat pump. Heat pumps will frost up and then go into defrost mode. Frost is normal. Particularly around 35-45 degrees outdoor temperature, ice is not good. Now it gets more exciting. Depending on year the unit was manufactured. The defrost will be either time/demand or both. Meaning if it is time demand defrost, it is probably a bad defrost control board 250 to 300 dollars most places. If it is demand defrost it is probably a defrost thermostat, 180 to 280 dollars many markets. If it is time demand it is a board with the thermostats wire to the board, a bit more money.