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920-087-06
Diagnostics
The Friedrich Smart Center continuously monitors the PTAC unit
operation and will store service codes if certain conditions are
witnessed. In some cases the unit may take action and shut the
unit off until conditions are corrected.
To access the error code menu press the ‘Heat’ and ‘High Fan’
buttons simultaneously for three seconds. If error codes are
present they will be displayed. If multiple codes exist you can
toggle between messages using the temp button. To clear
all codes press the temp button for three seconds while in
the error code mode. To exit without changing codes press the
‘Low Fan’ button.
Test Mode
For service and diagnostic use only, the built-in timers and
delays on the PTAC may be bypassed by pressing the ‘Cool’
and ‘Low Fan’ buttons simultaneously for three seconds while
in any mode to enter the test mode.
CE
will be displayed when
entering test mode, and
OE
will be displayed when exiting. The
test mode will automatically be exited 30 minutes after entering it
or by pressing the ‘Cool’ and ‘Low Fan’ buttons simultaneously
for three seconds.
Digital Control Diagnostics and Test Mode
The chart below lists the possible error codes and their description:
Error
Code
Code Translation Action Taken by Unit Possible Cause
EF
“Error Free” - No Codes Stored None Unit Operating Normally
02
An extreme low voltage condition exists
<198V for 230V units and <239V for 265V
units.
Shut down unit. Display Error code and fl ash.
Once voltage rises to normal level system power is
restored.
• Inadequate power supply
• Defective breaker
• Blown fuse
03
Return air thermistor sensor open or short
circuit
Set return air sensor = 75°F. Alternately fl ash set
point and error code. Leave unit running.
• Defective sensor
04
Indoor coil thermistor sensor open or short
circuit
Set ID coil temp = 40°F. Alternately fl ash set point
and error code. Leave unit running.
• Defective sensor
05
Outdoor coil thermistor sensor open Or
short circuit
Set OD coil temp = 20°F. Alternately fl ash set point
and error code. Automatically change over to Elec-
tric heat Mode only. Leave unit running.
• Defective sensor
06
If O.D. coil Temperature > 175 Deg F for 2
consecutive minutes. (Heat Pump models
only)
Alternately fl ash set point and error code. Shut unit
down for 5 minutes, then try again 2 times, if fails
the 3rd time then shut down unit.
• Dirty coil
• Fan motor failure
• Restricted air fl ow
• Non-condensables in
refrigeration system
07
I.D coil temperature <30 Deg F for 2 con-
secutive minutes.
Alternately fl ash set point and error code. Continue
fan operation while the compressor is locked out
until the indoor coil thermistor reaches 45° F, then
energize the compressor. However, compressor
must still wait a lockout time of 180 to 240 seconds.
• Dirty fi lters
• Dirty coil
• Fan motor failure
• Restricted airfl ow
• Improper refrigerant charge
• Restriction in refrigerant circuit
08
Unit cycles (Heat or Cool demand) > 9 times
per hour
Store error code in memory.
Keep unit running
• Unit oversized
• Low load conditions
09
Unit cycles (Heat or Cool demand) < 3 times
per hour
Store Error Code in memory.
Keep unit running
• Unit undersized
• High load conditions
10
Room Freeze Protection triggered Alternately fl ash set point and error code. Keep unit
running.
• Room temperature fell below
40°F
11
No Signal to “GL or “GH” terminal (Remote
Thermostat mode only)
Shut down unit. Display error code and fl ash. • Defective remote thermostat
• Defective thermostat wiring
12
Discharge air temperature >185º F Alternately fl ash set point and error code. Open all
relays and run high fan. If condition repeats three
times in one hour, shut down unit.
• Restricted air fl ow
• Fan motor failure
13
If Pressure limit switch opens
Turn OFF compressor. Alternate fl ash set point
and error code
14
Discharge air temperature sensor open or
shorted
Set the temperature sensor = 75º F Alternately fl ash
set point and error code. Leave unit running.
• Defective Sensor
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