Rheem 80MDV SERIES

73
TABLE 13 (continued)
802V FAULT CODES WITH DESCRIPTIONS AND SOLUTIONS
DESCRIPTION: The furnace control (I.F.C.) can not communicate with the blower motor.
SOLUTION
:
(1) Check wiring, connectors and terminals - repair or replace as necessary.
(4) The motor has failed catastrophically.
93
INTERNAL CONTROL FAULT DETECTED
STATUS: This is a critical fault. The furnace will not operate in any mode of operation.
DESCRIPTION: This is a severe fault that should rarely (if ever) be discovered in the field. It
is an indicator of an internal
microprocessor fault on the furnace control (or I.F.C.) or voltage applied to the main gas valve solenoid when there should be
none.
(1) Check for miswiring in the furnace.
(2) Replace the furnace control (or I.F.C.).
SOLUTION:
66
BLOWER CUTBACK
STATUS: This is a non-critical fault experienced by the furnace. All operations (including thermostat calls) should continue as
normal with no perceivable difference in operation.
DESCRIPTION
: The blower motor is operating at the highest rpm or torque that specifications allow but the application requires
more torque or speed in order to get the desired airflow under the current static pressure condit
ions. The motor will continue to
operate because internal software will prevent operation above the permitted range. However, a fault is sent to the furnace
control (or I.F.C.) from the motor. Note: Th is fault will
not be displayed after
the first three minutes of blower operation after power reset. Further, this fault will not be logged in the
fault buffer or fault history after the first hour of operation and will only be logged into the faul
t buffer a maximum of one time.
This code (66) indication is intended as a tool to notify the installer of inadequate airflow due to excessive static pressure in the
duct of the system. The code is not intended to
be a fault code. It is merely an operating indicator.
CAUSE
:
(2) Furnace control software test failure - failed furnace control (or I.F.C.).
(1) The blower has hit the maximum speed or torque limit specified by the manufacturer because the static pressure is too high.
SOLUTION
:
68
(2) There is no line voltage to the motor.
(3) The furnace model data is faulty or corrupted.
99
REMOTE FAULTS RESET PERFORMED
This is a notification that fault codes in the fault buffer have been reset.
NO BLOWER COMMUNICATIONS
STATUS: This is a critical fault. The furnace will not operate in any mode.
(1) 24VAC or similar voltage applied to the main gas valve solenoid circuit unexpectedly.
CAUSE:
EXPECTED OPE
RATION: If possible, if the furnace was in heating operation when this fault occurred, the gas valve will
immediately close (flame will be lost), IBM (Indoor Blower Motor) operation will immediately stop and
the furnace will shut down
normally (except without IBM operation) with IDM (Induced Draft Motor) post-purge at the correct speed. After the post purge (o
r
immediately if no heat call was present), no other operation (including thermostat calls) will occur until this fault is cleared.
However, this fault may also indicate an internal microprocessor failure. This may
mean that the heat call will not end as
expected and that all outputs will be de-energized and gas valve closed immediately when the fault is sensed.
(2) Check line voltage wiring, connectors and terminals to the Power Factor Correction choke and ECM motor. Repair and
replace as necessary.
(3) Replace the furnace memory card with the correct replacement part from ProStock.
(4) Replace the motor.
(1) The static pressure is too high because the ductwork is improperly
designed or is restricted for some other reason or the
filter needs cleaning or replacing. Remove the obstruction or repair the duct so that static pressure does not exceed published
values in the specification sheets or
installation instructions for the furnace.
CAUSE
:
(1) The wires between the blower motor have been disconnected or there is a poor connection.
EXPECTED OPERATION
: All (including thermostat) operation should continue as normal. Blower operation may be slightly
compromised but will continue.
EXPECTED OPERATION
: If the furnace was in heating operation when this fault occurred, the gas valve will immediately close
(flame will be lost), IBM (Indoor Blower Motor) operation will immediately stop and the furnace will shut down norma
lly (except
without IBM operation) with IDM (Induced Draft Motor) post-purge at the correct speed. After the post purge (or immediately if
no heat call was present), no other operation (including thermostat calls) will occur until this
fault is cleared.
Diagnostics