HVACopediaKeepRite · Furnace
10 Line voltage polarity reversed
What the control is telling you
The control sees 115 V polarity reversed (or the furnace is not grounded) and will not heat. On 96VTN the light flashes rapidly.
Applies to: KeepRite (F/G)9MXE, (F/G)9MXT and (F/G)96VTN furnaces
Likely causes
- Hot and neutral swapped
- Poor or missing ground
- Twinned units with 24 V transformers out of phase
Test and repair steps
- Turn power off and correct the hot/neutral connections to the furnace.
- Confirm a solid ground to the furnace and control.
- On twinned furnaces, check the 24 V transformer phasing.
Settings for these units
Filter size by casing width · KeepRite (F/G)96VTN Two-Stage Variable-Speed Furnace
| Casing width (in.) | Side return filter | Bottom return filter | Type |
|---|---|---|---|
| 14-3/16 | 16 x 25 x 3/4 in. | 14 x 25 x 3/4 in. | Washable |
| 17-1/2 | 16 x 25 x 3/4 in. | 16 x 25 x 3/4 in. | Washable |
| 21 | 16 x 25 x 3/4 in. | 20 x 25 x 3/4 in. | Washable |
| 24-1/2 | 16 x 25 x 3/4 in. | 24 x 25 x 3/4 in. | Washable |
Aim for filter pressure drop under 0.2 in. w.c. (best under 0.1).
Never run without a filter.
Models that show this code
25 models in KeepRite (F/G)9MXE Single-Stage Furnace, KeepRite (F/G)9MXT Two-Stage Furnace, KeepRite (F/G)96VTN Two-Stage Variable-Speed Furnace
Other codes on the same units
- 5 Flame sensed with gas valve off
- 6 Flame not proved during ignition trial
- 6+1 Ignition lockout after 4 failed tries
- 7 Limit circuit lockout
- 8 Gas heating lockout - manual reset needed
- 9 High-heat pressure switch or relay did not close or reopened
- LED off Status LED dark - no power to the control or blown 3 A fuse
- LED steady ON Status LED on solid - control lockout (resets after 1 hour)
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Source: KeepRite/ICP (F/G)9MXE Service and Technical Support Manual 440 04 4311 09, Fig. 16 troubleshooting flow chart, p.24-25; KeepRite/ICP (F/G)9MXT Service and Technical Support Manual 440 04 4321 10, Fig. 16, p.24-25; KeepRite_ICP_F_G_96VTN_KeepRite_G96VTN_Tempstar_Heil_Arcoaire_installation_440_01_4801_00.txt - section Start-up, Adjustment and Safety Check / 115-V Wiring. 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.