T4AE : High Temperature Heat Exchanger A

Open cabinet cover and turn switch to the OFF position.


Debris in valve diaphragm or plunger preventing spring-loaded closed function.  Disconnect connector from valve solenoid cable.  If temperature does not decrease, rebuild solenoid.  


If the blue and red LEDs are on while heat is off, the load center board is bad.  See Load Center Diagnostics in the system repair manual.