Brand: Allied Air Enterprises
Category: Heat Pump
Manual Type:
Language:
Manual for A98USMV
Uploaded: March 30, 2025, 4:25 p.m.
Warranty Summary
Warranty information is not present in this service manual.
The A98USMV gas furnace is a high-efficiency unit with variable capacity. Operation is managed by a thermostat, offering modes like variable capacity, three-stage timed, and two-stage. Upon a heat call, the combustion air inducer starts, followed by pre-purge and ignitor warm-up. Gas valve opens for ignition, and the indoor blower starts after a delay. Firing rate adjusts based on thermostat demand and selected mode, ranging from 35% to 100%. Safety checks, including pressure and limit switches, are continuously monitored. Post-purge and blower off delay conclude the heating cycle. Cooling operation is also supported, with blower speed and ramping profiles configurable for dehumidification and comfort.
Troubleshooting and error codes
| Code | Diagnostic Codes / Status of Equipment | Action Required to Clear and Recover |
|---|---|---|
| Idle mode (Decimal blinks at 1 Hertz - 0.5 seconds ON, 0.5 seconds OFF). | ||
| A | Cubic feet per minute (cfm) setting for indoor blower (1 second ON, 0.5 seconds OFF) / cfm setting for current mode displayed. | |
| C | Cooling stage (1 second ON, 0.5 seconds OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes. | |
| d | Dehumidification mode (1 second ON, 1 second OFF) / cfm setting displayed / Pause / Repeat codes. | |
| h | Heat pump stage (1 second ON, 0.5 seconds OFF) / % of input rate displayed / Pause / cfm setting / Pause / Repeat codes. | |
| H | Gas Heat stage (1 second ON, 0.5 seconds OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes. Blinking during ignition. | |
| dF | Defrost mode. | |
| U | Discharge Air Temperature | |
| E105 | Device communication problem - No other devices on RS BUS (Communication system). | Equipment is unable to communicate. Indicates numerous message errors. In most cases, errors are related to electrical noise. Make sure high voltage power is separated from RSBus. Check for mis-wired and/or loose connections between the stat, indoor unit, and outdoor unit. Check for a high voltage source of noise close to the system. Fault clears after communication is restored. |
| E110 | Low line voltage. | Line Voltage low (Voltage tower than nameplate rating). Check power line voltage and correct. Alarm clears 5 seconds after fault recovered. |
| E113 | High line voltage. | Line Voltage high (Voltage higher than nameplate rating). Provide power voltage within proper range. System resumes normal operation 5 seconds after fault recovered. |
| E114 | Line voltage frequency out-of-range. | No 60 Hertz power. Check voltage and line power frequency. Correct voltage and frequency problems. System resumes normal operation 5 seconds after fault recovered. |
| E115 | Low 24V - Control will restart if the error recovers. | 24 Volt Power high (Range is 18 to 30 Volts). Check and correct voltage. Check for additional power robbing equipment connected to system. May require installation of larger VA transformer to be installed in furnace/air handler. Clears after fault recovered. |
| E120 | Unresponsive device (Communicating systems only). | Usually caused by delay in outdoor unit responding to indoor unit poling. Recycle power. Check all wiring connections. Cleared after unresponsive device responds to any inquiry. |
| E124 | Active communicating thermostat signal missing for more than 3 minutes (Communicating systems only). | Equipment lost communication with the thermostat. Check four wiring connections, ohm wires, and cycle power at the thermostat. Alert stops all services and waits for heartbeat message from thermostat (subnet controller). Cleared after valid thermostat (subnet) message is received. |
| E125 | Control failed self-check, internal error, failed hardware. Will restart if error recovers, Integrated control not communicating Covers hardware errors (flame sense circuit faults, pin shorts, etc). | Hardware problem on the control. Cycle power on control. Replace if problem prevents service and is persistent. Cleared 300 seconds after fault recovered. |
| E126 | Control internal communication problem. | Hardware problem on the control. Cycle power on control. Replace if problem prevents service and is persistent. Cleared 300 seconds after fault recovered. |
| E131 | Corrupted control parameters (Verify configuration of system) (Communicating systems only). | Reconfigure the system. Replace control if heating or cooling is not available. Only applicable in the communicating mode not in startup. Exit from Commissioning and Execute Se+ factory Default mode. Control will still operate on default parameter settings. |
Troubleshooting and error codes
| Code | Diagnostic Codes / Status of Equipment | Action Required to Clear and Recover |
|---|---|---|
| Idle mode (Decimal blinks at 1 Hertz - 0.5 seconds ON, 0.5 seconds OFF). | ||
| A | Cubic feet per minute (cfm) setting for indoor blower (1 second ON, 0.5 seconds OFF) / cfm setting for current mode displayed. | |
| C | Cooling stage (1 second ON, 0.5 seconds OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes. | |
| d | Dehumidification mode (1 second ON, 1 second OFF) / cfm setting displayed / Pause / Repeat codes. | |
| h | Heat pump stage (1 second ON, 0.5 seconds OFF) / % of input rate displayed / Pause / cfm setting / Pause / Repeat codes. | |
| H | Gas Heat stage (1 second ON, 0.5 seconds OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes. Blinking during ignition. | |
| dF | Defrost mode. | |
| U | Discharge Air Temperature | |
| E105 | Device communication problem - No other devices on RS BUS (Communication system). | Equipment is unable to communicate. Indicates numerous message errors. In most cases, errors are related to electrical noise. Make sure high voltage power is separated from RSBus. Check for mis-wired and/or loose connections between the stat, indoor unit, and outdoor unit. Check for a high voltage source of noise close to the system. Fault clears after communication is restored. |
| E110 | Low line voltage. | Line Voltage low (Voltage tower than nameplate rating). Check power line voltage and correct. Alarm clears 5 seconds after fault recovered. |
| E113 | High line voltage. | Line Voltage high (Voltage higher than nameplate rating). Provide power voltage within proper range. System resumes normal operation 5 seconds after fault recovered. |
| E114 | Line voltage frequency out-of-range. | No 60 Hertz power. Check voltage and line power frequency. Correct voltage and frequency problems. System resumes normal operation 5 seconds after fault recovered. |
| E115 | Low 24V - Control will restart if the error recovers. | 24 Volt Power high (Range is 18 to 30 Volts). Check and correct voltage. Check for additional power robbing equipment connected to system. May require installation of larger VA transformer to be installed in furnace/air handler. Clears after fault recovered. |
| E120 | Unresponsive device (Communicating systems only). | Usually caused by delay in outdoor unit responding to indoor unit poling. Recycle power. Check all wiring connections. Cleared after unresponsive device responds to any inquiry. |
| E124 | Active communicating thermostat signal missing for more than 3 minutes (Communicating systems only). | Equipment lost communication with the thermostat. Check four wiring connections, ohm wires, and cycle power at the thermostat. Alert stops all services and waits for heartbeat message from thermostat (subnet controller). Cleared after valid thermostat (subnet) message is received. |
| E125 | Control failed self-check, internal error, failed hardware. Will restart if error recovers, Integrated control not communicating Covers hardware errors (flame sense circuit faults, pin shorts, etc). | Hardware problem on the control. Cycle power on control. Replace if problem prevents service and is persistent. Cleared 300 seconds after fault recovered. |
| E126 | Control internal communication problem. | Hardware problem on the control. Cycle power on control. Replace if problem prevents service and is persistent. Cleared 300 seconds after fault recovered. |
| E131 | Corrupted control parameters (Verify configuration of system) (Communicating systems only). | Reconfigure the system. Replace control if heating or cooling is not available. Only applicable in the communicating mode not in startup. Exit from Commissioning and Execute Se+ factory Default mode. Control will still operate on default parameter settings. |