84 Outdoor air sensor fault

What the control is telling you

The optional outdoor air sensor on T4 (10K NTC) read open or shorted after it had been seen as valid in this power cycle. Low-level fault: heating continues. It clears itself three minutes after it is detected and is only logged once.

Applies to: (-)96VA040-115 (R96V / U96V) and (-)(-)96MDV040-115 two-stage variable-speed communicating furnaces

Likely causes

• Outdoor sensor wire broken or shorted
• Sensor unplugged after power-up
• Failed sensor

Test and repair steps

1. Check the OAT sensor wiring at terminal block T4.
2. Measure the sensor a 10K NTC thermistor, about 10,000 ohm at 77 F.
3. Replace the sensor if it reads open or shorted; or remove it completely and cycle power if it is not wanted.

Settings for these units

• Filter sizes · Rheem RGRM/RGTM 90 Plus
• Filter sizes (Table 12) · Rheem 90RJ/90TJ 90 Plus
• Minimum clearance to combustibles · Rheem 90RJ/90TJ 90 Plus
• Filter sizes (Table 9) · Rheem (-)GRC/(-)GTC 90 Plus
• Minimum clearance to combustibles · Rheem (-)GRC/(-)GTC 90 Plus
• Clearance to combustibles (all models) · R95P

Models that show this code

12 models in R96V/96MDV

Other codes on the same units

• 60 Blower fault - running (BLWR FLT-RUN)
• 61 Blower fault - blower not running
• 66 Blower overspeed (BLOWER OVRSPEED)
• 68 No blower communication (NO BLWR COMM)
• 82 Supply air sensor fault (SA SENSOR FLT)
• 93 Internal control fault
• d1 No shared data (NO SHARED DATA)
• d4 Memory card invalid (MEM CARD INVALD)