Rheem Furnace: Heat call troubleshooting walk-through (two-stage communicating IFC)
Heat call troubleshooting walk-through (two-stage communicating IFC) on a Rheem furnace: Order of checks from the factory diagnostic chart when a heat call does not end in high-fire heat.
Applies to: (-)96VA040-115 (R96V / U96V) and (-)(-)96MDV040-115 two-stage variable-speed communicating furnaces
Common causes of heat call troubleshooting walk-through (two-stage communicating ifc)
- No W1/W2 or communicated call
- Dipswitch or test-mode setting
- Inducer not starting or pressure switches not closing
- No spark or no flame proof
- Blower not starting on heat speed
How to fix heat call troubleshooting walk-through (two-stage communicating ifc): step by step
- Communicating systems: pull E1/E2 off the thermostat and jumper W1-R and W2-R to force high heat. Legacy: confirm 24 VAC on W1 and W2 at the IFC.
- Displays should light and show a steady H (h = low heat only). Flashing H means check the dipswitches.
- Inducer should pre-purge about 30 seconds at high speed. If it runs 60 seconds then stops for five minutes with 45, 46 or 57 showing, work the pressure switch fault.
- Watch for spark; the gas valve is powered about 7 seconds per trial, four trials before a one-hour lockout. 11 or 13 = flame not proven, 12 = weak flame (furnace still runs).
- The blower should come on at high heat speed roughly 15 to 20 s after the burners light; if 22 or 33 shows, check airflow, limits, rollouts and overfiring.
- Remove the W2 call and confirm the inducer and blower switch to low; then end the call and confirm post-purge and the blower off delay.
- To reset a lockout: cut main power 30 seconds, or remove the heat call for more than 2 but less than 20 seconds (soft lockout).
If the unit shows an error code, look it up: Rheem Furnace codes
Models
96MDV040B30A96MDV060B30A96MDV070B30A96MDV085C50A96MDV100C50A96MDV115D50AR96VA0401317MSAR96VA0601317MSAR96VA0701317MSAR96VA0851521MSAR96VA1001521MSAR96VA1151524MSA
Source: Rheem (-)96V / (-)(-)96MDV Installation Instructions 92-24161-124-08, Fig. 64 2-stage furnace troubleshooting chart p.124-125. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.