Verifying Code

Prior to beginning it is recommended to first verify the code is actually an Eb and not an E6.  The Eb error code is many times mistaken for a E6 error code instead. To verify see if the top of the second digit has a red line across it or not. No line across it makes it a b, if there is a line across it then it is a 6.

See the picture below

What will cause an Eb error code

• Eb can be caused by a Y1 without a G
• Eb can be caused by a Y1 before G call (New board replacement and A2L units now have a 5-minute delay for G call)
• W1 without a G (on electric heat units)
• Y2 before Y1
• Heat / Cool call simultaneously
• Broken thermostat wire
• Bad thermostat
• Miss wiring
• Safety devices wired into the thermostat low voltage (Smoke Detectors, Overflow pan switch's, etc.)

Symptoms related to Eb error code

• No 24 VAC at the thermostat
• Unit Lockout

How to troubleshoot the Eb error code

• Make sure the thermostat wires are landed correctly between the low voltage terminal board and the thermostat. 
• Make sure there are no broken wires between the two visually and with an OHM meter. 
• After verifying the wiring connections and wire is in good working order, give the unit a call for fan only operation and verify 24 vac is present on the unit's main board between G and C. If no voltage is present the repeat steps 1 & 2. 
• Next remove the fan only call from the stat and give the unit a Y1 call for cooling. Allow thermostat timer time to send call to the unit's main board.
•  After the stat timer has passed, verify the call is present on the G terminal to C and also from Y1 to C. If not repeat steps 1 & 2. 
• For older generation Main boards there is no 5-minute timer. On replacement boards and new A2L units the timer has been added. The new boards and new units allow for the stat to have 5 minutes for the G call to be made after Y1 for unit operation. The unit operation will not begin until both the Y1 & G call from the stat is present at the Main board. 

How to bypass thermostat for testing

• Remove low voltage wires from Main board terminal block and apply a jumper between R, G, & Y1 for temporary testing purposes. This is not intended for permanent operation and is only recommended during service for testing purposes only. Remove once testing for the day has been completed. 
• To verify stat operation if need, temporary installation of the thermostat to the unit main board with a small piece of wire will allow for stat testing and unit operation if needed. 

Cooling sequence of operation

• After a power cycle, when the unit receives a Y1/G signal, Compressor A is delayed for 3 minutes to start.
• After the first Y1 / G call, each subsequent Y1 call has a 7-minute delay.
• When the unit receives a Y2 signal after compressor A is turned on, compressor B is delayed for 3 seconds to start.
• When the unit receives a Y1 signal, only one compressor is turned on. Compressor A and compressor B are rotated according to the running time. (Running times are tracked on the board and cannot be viewed.

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.