Diagnostic Codes - Friedrich VRP Series Service & Parts Manual

Diagnostic Codes

Diag Description
Return Air sensor (T8) is
3
open or shorted
Indoor Coil Cool Inlet sensor
4
(T1) is open or shorted
Outdoor Coil Heat Inlet sensor
5
(T7) is open or shorted
Discharge Air sensor (T9)
6
is open or shorted
Outdoor Ambient Air sensor
7
(T10) is open or shorted.
Indoor Coil Heat Cond. sensor
8
(T5) is open or shorted.
Compressor Discharge sensor
9
(T4) is open or shorted.
Compressor Suction sensor
10
(T3) is open or shorted.
Liquid Cool sensor (T6)
11
is open or shorted
Liquid Heat sensor (T2)
12
is open or shorted
13 Humidity sensor is open or shorted.
14 High or Low Pressure Limit Switch Open
16 Compressor Model Code Error
17 Compressor Output Phase Loss
19 Outdoor Coil > 175°F
66
TROUBLESHOOTING
Diagnostic Check point
1. An open or shorted sensor is
detected by the A/D conversion
value residing at the upper or lower
end of the conversion range.
2. The Ambient Indoor Temperature
Sensor(T8) is open or shorted
3. Defective contact between
male and female electrical
molex connectors.
4. The sensor is not properly
connected to the FMC.
1. The wall controller is not properly
connected to the FMC.
2. There is an issue with the sensor itself.
1. Pressure of suction line is too low.
2. Pressure of discharge line is too high.
3. Quick connects on FMC board are loose
or damaged.
4. Faulty high or low pressure switch.
"Motor board does not recognize the
model code that is sent by
the FMC."
When the motor boad sees an issue with at
least one of the compressor wire outputs.
1. The Outdoor Coil reaches a temperature
greater than 175°F
2. Outdoor fan is not running when the
compressor is on in cool.
3. EEV malfunction
4. Sealed system restriction.
5. Imporoper installation causing outdoor
air recirculation.
Solution
1. Disconnect the sensor at the FMC then
reconnect.
2. Ohm out the sensor to determine the
failure point and correct as needed.
Refer to Component Testing (Thermistor
Values)
3. Replace the FMC board.
1. Verify that the wall controller is
correctly connected to the unit, if it is and
the problem persists, replace the wall
controller.
1. Check high and low pressure switches
per procedure located in the component
testing section of this manual.
2. Check EEV per procedure located in the
component testing section of this manual.
3. Determine cause of leak or restriction in
sealed system and repair.
1. Replace the motor board.
"1. Check compressor wires for any
damage.
2. Verify connection of the compressor
wires.
3. Replace the motor board."
1. Ensure that the Outdoor fan is properly
connected and operational
2. Check EEV per procedure located in the
component testing section of this manual.
3. Repair sealed system restriction
problem.
4. Outdoor Fan replacement.
5. Ensure proper installation of unit and
baffle per Installation section of this
manual.