Make:  Goodman

Model or Series:  GMPN120-5

Type:  90% Furnace

Problem Description:  No power to thermostat

Observed Symptoms:  

• Control board flashing Code 4 (Limit switch open)
• No 24VAC at "R" terminal

Solution:  Replaced furnace control board. ICM280

Additional Information:  

• Had 24VAC on 12-pin connector at "Limit Out" and "Limit In"
• Cycled power and still flashing Code 4