Diagnostic Display; Short Cycle Timer Override; Low Temperature Lockouts; Other Speed Overrides - Maytag iQDrive SA1BG4MV Series Installation Instructions Manual

The actual current operating compressor speed can be
determined by checking the 2-character display on the interface
board. Refer to Figure 9 (page 14)
Control operation is protected under U.S. patent number
US 8,011,199 B1.

Diagnostic Display

The interface board located inside the control panel has a
two character display which provides information regarding
operational status and fault history. When 24 vac control
power is provided to the board, the display will show some
combination of characters. In order to diagnose a problem
with the unit, or to determine its operational status, remove
the control panel cover, then observe the 2-character lighted
display on the interface board. Refer to
and Table 6 (page 8).
When control power is first applied to the control board, the
2-character display will show the following three items in
sequence, twice:
• Unit size (tons): , , 4, or 
• Unit type: AC for air conditioner
• Software version, e.g. 4.
This power-up display sequence is intended to confirm the
correct programming of the inverter control board.
After power-up, the display will alternate between an operating
code (Table 5) and a list of the codes for up to the last 20
different faults or warnings. When this list is being displayed,
each diagnostic code in memory will be displayed for 5 seconds.
The most recent code will be the first one appearing in the
series of codes displayed.
NOTE: If there is a fault that is "active" when the display is
viewed, the decimal point to the right of the right side character
will be lit. The code for the most recent active fault will flash
three times before the remainder of the fault history list is shown.
Fault codes are retained through loss of power.Any fault which
has been in the list for more than 7 days (with control power
applied) will be removed. When there are no active faults, the
list of past fault codes can be cleared by shorting the TEST
pins (J4, at the lower right side of the inverter control board)
when the unit is powered up but not running.
NOTE: This action may also have other consequences - See
Short Cycle Timer Override section above.
DISPLAY CAPACITY STAGE OR STATUS
C1
C
Cooling, Stage One Call, Intermediate
C
Cooling, Stage One Call, Low High
C4
Cooling, Stage Two Call, Nominal High
C
C_,d
_

Cooling Low Temperature Lockout (< 50° F)
Table 5. Interface Board Operating Codes
and Table 5.
Table 5 (page 7)
Cooling, Stage One Call, Low
Cooling, Stage Two Call, Boost
Startup Delay (5 minutes)
System Powered but Idle

Short Cycle Timer Override

When performing startup tests or while troubleshooting, the
5 minute startup delay can be skipped by shorting the two J4
Test pins indicated in Figure 9
compressor is off and waiting to start.
NOTE: Use this feature with forethought because it will also
clear the fault codes stored in memory, which can make
troubleshooting more difficult.

Low Temperature Lockouts

The control will not permit the unit to operate at ambient
temperatures below 50° F. If there is a call for air conditioning
when the temperature drops below this point, the unit will shut
down (if running), and diagnostic code 9 will be displayed on
the interface board. The status code  (for Low Temperature)
will also appear. Once this lockout is in effect, the unit can
resume cooling after ambient temperature has risen again
above 55° F.

Other Speed Overrides

When ambient temperature is high, exceeding 105° F, the
compressor speed may be reduced to limit current draw or
inverter component temperature. Whether or not this occurs
and to what degree the speed is reduced depends upon the
unit model and the specific operating conditions as detected
by the inverter. Speed will return to the normal value when the
high current or temperature condition is relieved. In addition,
any time outdoor ambient temperature exceeds 100° F, the
fan will operate at its maximum speed.

Instrumentation

The 20 SEER iQ Drive split system air conditioner includes
instrumentation as listed in
listed are connected to the interface board except for the high
pressure switch. Refer to
14), Figure 10 (page 15), and
two temperature sensors are color coded so that the color of
the wire insulation matches the color of the connector base
on the left side of the circuit board. All temperature sensors
are 10k ohm thermistors. The resistances of these sensors
(when disconnected from the interface board) may be checked
against Figure 12 (page 17)
Figure 12 shows the thermistor resistance-temperature curve
broken into two parts for ease of use.
for about 1 second while the
Table 7 (page 8). All items
Figure 4 (page 12), Figure 9 (page
Figure 11 (page
for troubleshooting purposes.
16). The
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