GE Profile RV air conditioner and RARWT thermostat fault codes
GE Appliances' rooftop units (ARC cool-only, ARH heat pump) on Keystone, Forest River, Grand Design and others. The rooftop plugs into the ceiling control box with one 6-pin connector; the main board lives in that box (three screws, the bottom hinges down). The RARWT wall thermostat talks to the board over one signal wire: three wires at the stat, +12 V (red), COMMS (yellow) and ground (black). The furnace runs from two blue wires at the box. The codes on the screen come from the board; the stat only shows them. Fan-only running with a code on the screen proves the board and the comms wire are alive.
GE Profile AC code F1
Freeze sensor open or reading below -22°F. GE calls it the indoor coil sensor. Its plug hides up inside the return, above the filter, not in the control box: pull the filter and seat it. Then the probe in the coil's thermistor well, and the lead where it leaves the rooftop (pinched under the base pan when the unit was set). Unplugged, the sensor reads thousands of ohms that drop as the probe warms; OL is the fault. A 10 kΩ resistor in its place clears F1 if the board is fine.
GE Profile AC code F2
Freeze sensor shorted, or reading above 149°F. Reseat the plug; ohm the lead (near 0 Ω is the fault); replace the sensor.
GE Profile AC code F3
Outdoor coil sensor open (heat pump models). Reseat, ohm, replace. ARH only.
GE Profile AC code F4
Outdoor coil sensor shorted (heat pump models). Reseat, ohm, replace. ARH only.
GE Profile AC code F5
Outdoor temperature sensor open, or DIP switch 1 ON on a cool-only unit. On an ARC unit, DIP 1 at the stat goes OFF. On an ARH, reseat, ohm, replace the ambient sensor.
GE Profile AC code F6
Outdoor temperature sensor shorted (heat pump models). Reseat, ohm, replace. ARH only.
GE Profile AC code F7
The stat's own room sensor open. This one is in the thermostat. Replace the stat.
GE Profile AC code F8
The stat's own room sensor shorted. Replace the stat.
GE Profile AC code FC
No communication with the main board: the comms (signal) wire open or shorted. Reseat the 3-wire plug at the stat and the yellow wire at the box. Look for a pinch at the stat plate and at a slide. Also shown as two dashes.
GE Profile AC code Lo
12 V under 10.5 V: the stat drops to OFF. Fix voltage first: battery, converter, drop to the box under compressor start. After it recovers the screen shows a solid Lo and stays OFF until you pick a mode again.
GE Profile AC: Snowflake flashing
Indoor coil near freezing: compressor off, fan on. Airflow: filter, return opening, closed vents. Not a sensor fault.
GE Profile AC: Heat pump icon flashing with 32
Outdoor temperature under the heat pump lockout. Normal. Use heat pump + furnace or furnace only.
GE Profile AC: Heat pump icon flashing with 99
Indoor coil over 135°F: compressor off. Airflow across the indoor coil.
GE Profile AC: Blank display
No 12 V at the stat. 12 V and ground at the 3-wire plug; the stat is fed from the control box.
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Guided diagnosis
Full field guide: GE Profile RV air conditioner and RARWT thermostat
Codes come from the maker manuals and public service sheets. Your model's own chart always wins, and LP and 120 volt work belongs to a qualified technician.