Trane · Air conditioner

F9 Drive (MOC) internal fault

High severity Trane 5TTR7

What the control is telling you

Internal fault in the drive board. Manual lists only the meaning (A1000BA board); steps are general checks drawn from other sections of the guide.

Applies to: Trane 5TTR7 multi-speed AC (5TTR7024A-060A)

Likely causes

Loose AOC-MOC harness
Drive or control board fault

Test and repair steps

Warning: After power off, wait 2 minutes - the inverter can hold 400 VDC. Confirm under 42 VDC at the +DC/-DC test points before touching the board.
Check the AOC-MOC interface harness between the control and the drive.
Cycle power and watch whether the fault returns.
Replace the drive or control board if wiring is good.

Settings for these units

Outdoor unit placement · Trane 5TTR7

Item	Value
Above unit	5 ft clear
Service side	3 ft
Walls / shrubs	12 in. min
Pad	1 in. larger than unit all round, level, separate from house
Cold climate (HP)	raise 3-12 in. above pad
Within 1 mile of salt water	add BAYSEAC001 if no factory salt shield
Operating range	cooling 55-120 F, heating 0-66 F

Avoid bedroom walls and under roof drip lines.

Dimensions and weights · Trane 5TTR7

Model	H x D x W (in.)	Weight (lb)
5TWR7024A	41 x 30 x 33	181
5TWR7036A	41 x 30 x 33	194
5TWR7048A	41 x 34 x 37	231
5TWR7060A	41 x 34 x 37	241
5TTR7024A	41 x 30 x 33	176
5TTR7036A	41 x 30 x 33	189
5TTR7048A	41 x 34 x 37	226
5TTR7060A	41 x 34 x 37	236

Weights are estimated, uncrated.

Models that show this code

4 models in Trane 5TTR7

5TTR7024A5TTR7036A5TTR7048A5TTR7060A

Other codes on the same units

F5 AC over-current fault
F6 Drive high temperature fault
F7 AC input voltage low
F8 DC output voltage fault
H5 Hard lock: drive AC input over-current
H6 Hard lock: high drive IPM temperature
H7 Hard lock: high drive PFC temperature
H8 Hard lock: high coil temperature

Save it for the next call

Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.

Open the app

Source: Trane ODR-SVN002E-EN (5TTR7/5TWR7 installer's guide) - section Integrated Variable Speed Control Board LED Indicators, Table 18 (A1000BA models). Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.