Cause of error code A08

Fan error

Solution for error code A08

1. Is Combustion Air Blower operating?
Yes: -> 2.
No: -> 4.

2. Disconnect 4-wire harness from Combustion Air Blower. Does Combustion Air Blower speed increase?
Yes: -> 3. 
No: Replace Combustion Air Blower.

3. Disconnect harness from Control Module J9. Continuity in each wire of 4-wire harness (yellow, red, white, black)?
Yes: Replace Control Module.
No: Replace harness. 

4. Are 3-wire and 4-wire harnesses connected to Combustion Air Blower?
Yes: -> 5. 
No: Connect harness.

5. Disconnect harness from Control Module J9. Measure voltage between J9-2 and J9-3. Is voltage 120 Vac ± 10% 
Yes: -> 6.
No: Replace Control Module. 

6.  Disconnect 3-wire harness from Combustion Air Blower. Measure continuity in each wire. Continuity in each wire? 
Yes: Replace Combustion Air Blower. 
No: Replace harness