My indoor/outdoor temperature unit no longer will display outdoor temperatures

Try cleaning the outdoor thermometer transmitter unit by opening it up enough to spray compressed air (Ultra Duster or similar) on the temperature sensor. It fixed the hh.h error for me.

14.2.2 To Make a Diagnosis1 Timer LED starts to blink and the unit automatically stops the operation.
2 Press the CHECK button on the remote control continuously for 5 seconds.
3 "- -" will be displayed on the remote control display.
Note: Display only for "- -" (No signal transmission, no receiving sound and no Power LED blinking)
4 Press the TIMER ? or ? button on the remote control. The code "H00" (no abnormality) will be displayed
and signal will be transmit to the main unit.
5 Each press of the button (? or ?) will increase error code
number and transmit error code signal to the main unit.
6 When the latest abnormality code on the main unit and
code transmitted from the remote control are matched,
Power LED will light up for 30 seconds and a "beep" sound
(continuously for 4 seconds) will be heard. If no codes are
matched, Power LED will light up for 0.5 seconds and no
sound will be heard.
7 The breakdown diagnosis mode will be canceled unless
pressing the CHECK button continuously for 5 seconds or
operating the unit for 30 seconds.
8 The LED will be off if the unit is turned off or the RESET
button on the main unit is pressed.
Diagnosis
display Abnormality / Protection control Abnormality
Judgement Emergency operation Primary location to verify H00 No abnormality detected - Normal operation H11 Indoor / Outdoor abnormal communica
tion > 1 min after starting
operation Indoor fan operation
only • Internal / external cable connections
• Indoor / Outdoor PCB H14 Indoor intake air temperature sensor
abnormality Continue for 5 sec. - • Intake air temperature sensor (detec
tive or disconnected) H15 Outdoor compressor temperature sensor
abnormality Continue for 5 sec. - • Compressor temperature sensor
(detective or disconnected) H16 Outdoor Current Transformer open cir
cuit - - • Outdoor PCB
• IPM (Power transistor) module H19 Indoor fan motor mechanism locked 7 times occurance
continuously - • Indoor PCB
• Fan motor H23 Indoor heat exchanger temperature sen
sor abnormality Continue for 5 sec. O
(Cooling only) • Heat exchanger temperature sensor
(detective or disconnected) H24 Indoor heat exchanger temperature sen
sor 2 abnormality Continue for 5 sec. - • Heat exchanger temperature sensor
(detective or disconnected) H27 Outdoor intake air temperature sensor
abnormality Continue for 5 sec. O • Outdoor temperature sensor (detec
tive or disconnected) H28 Outdoor heat exchanger temperature
sensor abnormality Continue for 5 sec. O • Outdoor heat exchanger temperature
sensor (detective or disconnected) H30 Outdoor discharge air temperature sen
sor abnormality Continue for 5 sec. - • Outdoor temperature sensor (detec
tive or disconnected) H33 Indoor / Outdoor wrong connection - - • Indoor / Outdoor supply voltage H38 Indoor / Outdoor mismatch (brand code) H50 Ventilation motor abnormality 7 times occurance
continuously - • Indoor PCB
• Ventilation motor H51 Nozzle lock abnormality 2 times occurance
continuously - • Nozzle H52 Limit switch abnormality - - • Indoor PCB H97 Outdoor fan motor mechanism locked 2 times occurance
within 30 minutes - • Indoor PCB
• Fan motor H98 Indoor high pressure protection - - • Air filter dirty
• Air circulation short circuit H99 Indoor heat exchanger anti-freezing pro
tection - - • Insufficient refrigerant
• Air filter dirty F11 Cooling / Heating cycle changeover
abnormality 4 times occurance
within 30 minutes - • 4-way valve
• V-coil F90 PFC control 4 times occurance
within 10 minutes - • Voltage at PFC F91 Refrigerantion cycle abnormality 2 times occurance
within 20 minutes - • No refrigerant
(3-way valve is closed) F93 Compressor rotation failure 4 times occurance
within 20 minutes - • Compressor F95 Cool high pressure protection 4 times occurance
within 20 minutes - • Outdoor refrigerant circuit F96 IPM (power transistor) overheating pro
tection 4 times occurance
within 30 minutes - • Excess refrigerant
• Improper heat radiation
• IPM (Power transistor) F97 Outdoor compressor overheating protec
tion 4 times occurance
within 10 minutes - • Insufficient refrigerant
• Compressor F98 Total running current protection 3 times occurance
within 20 minutes - • Excess refrigerant
• Improper heat radiation F99 Outdoor Direct Current (DC) peak detec
tion 7 times occurance
continuously - • Outdoor PCB
• IPM (Power transistor)
• Compressor

Note:
"O" - Frequency measured and fan speed fixed.
The memory data of error code is erased when the power supply is cut off, or press the Auto Switch until "beep" sound heard following by pressing the "CHECK" button at remote controller.
Although operation forced to stop when abnormality detected, emergency operation is possible for certain errors (refer to Error Codes Table) by using remote controller or Auto Switch at indoor unit. However, the remote controller signal receiving sound is changed from one "beep" to four "beep" sounds.

Did you reset the sensors after replacing the batteries? Bring the sensor inside and close to the main unit. Replace batteries on both units. Use a thumb tack and stick it into small reset hole near battery compartment to reset both units. If that doesn't work, your sensor needs more troubleshooting or needs to be replaced.

often removing the batteries in both units will reset. replace batteries in indoor unit firs, let it settle down then insert batteries into outdoor unit. There may be a button on outdoor unit to initialise the connection.

Alternatively you might find the manual here or get the instructions from their support.

http://www.orbyxelectronics.com/manuals.asp?choice1=3&choice2=14&hidPickIndex=2