T4AE : High Temperature Heat Exchanger A

To avoid serious injury follow all warnings and instructions in the manual. Wear appropriate personal protective equipment.

Manual valve switch (MV) on load center is in the ON position

Open cabinet cover and turn switch to the OFF position.

A or B side control valve solenoid is stuck in the open 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.

Short on load center board

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.