TQM FC32 & FC39 – Combustion Air Pressure Fault / Sensor Error – ICS Filter 652063 & Hose Fix
⚠️ Safety Notice – Gas Heating Products
This appliance must only be installed, commissioned, serviced and repaired by suitably qualified and licensed personnel.
Before commencing work, complete a task-specific risk assessment and ensure gas and electrical safety requirements, ventilation provisions, safe access, adequate service clearances and appropriate PPE have been considered. All work must comply with applicable regulations, standards and manufacturer requirements.
Particular care must be taken when working around gas systems, electrical components, combustion products, hot surfaces, moving parts, roof spaces, ceiling spaces and confined spaces.
Do not proceed if safe access, required clearances, ventilation requirements, confined space risks or appropriate safety controls cannot be achieved and maintained.
Safety takes priority over diagnosis, repairs, installation schedules and customer expectations. If the task cannot be completed safely, it must not proceed until the risks have been adequately controlled.
Applicable Models
- TQM / TQMD / TQS modulating heaters
- ICS control systems
Fault Description
| Fault Code | Description |
|---|---|
| FC32 | Combustion air pressure too low at startup |
| FC39 | Combustion air pressure sensor error |
Triggered when:
- ICS cannot detect correct pressure during startup
- Pressure signal is unstable or inaccurate
Common Field Symptoms
- Heater fails to start or retries repeatedly
- Combustion fan runs → unit locks out
- Repeated FC32 / FC39 in fault history
REQUIRED FIRST ACTION (DO THIS BEFORE PART REPLACEMENT)
1. Confirm Hose Configuration (Critical – High Failure Cause)
If hose has been modified (lengthened):
- MUST be returned to factory configuration
Correct setup:
- Short grey hose
- Original spigot through divider panel
Why this matters:
- Long hoses = inaccurate pressure signal
- Slow response at startup
- Unstable readings → repeat faults
2. Swap Pressure Sensor Hoses (Proven Field Fix)
- Swap the two grey hoses at the ICS pressure sensor
- Hoses are NOT polarity sensitive
Effect:
- Clears moisture / debris
- Restores pressure signal stability
Often resolves issue without replacing parts
3. Fit ICS Filter (P/N 652063)
Install if:
- Repeat FC32 / FC39 faults
- No obvious restriction found
- Moisture or contamination suspected
ROOT CAUSES
- Restricted combustion air flow
- Moisture / condensate in hose
- Blocked suction hose
- Incorrect hose length/configuration
- Pressure sensor contamination
CHECKS (BEFORE REPLACING ICS)
1. Combustion Fan
- Confirm fan operation
- Check:
- Jammed fan wheel
- Loose assembly
- Power supply
Refer: Braemar TQ Gas Heater Component Testing & Fault Diagnosis TQ Service Guide 2023 (644066M): Seeley International Pty Ltd → 6.2 Combustion Fan Testing (24Vdc)
2. Air Path / Flue
- Check for:
- Flue blockage/restriction
- Incorrect cowl installation
- High wind exposure issues
3. Pressure Sensing System
Inspect hoses:
- No kinks / splits / blockages
- No condensate (very common)
Confirm:
- Factory hose length
- No water traps
4. Heater Assembly
- Check:
- Black joiner (no cracks/leaks)
- Proper alignment and sealing
5. ICS / Pressure Sensor
- Check:
- Sensor port not blocked
- Connections secure
WHEN TO REPLACE ICS PCB
Only replace after ALL checks completed:
Hose configuration correct
No blockages or moisture
Fan and flue OK
ICS filter fitted
If FC39 persists:
- Pressure sensor likely faulty
- Sensor is integrated in ICS board
- Replace ICS PCB (sensor not serviceable)
RESET PROCEDURE
- MagIQtouch → Retry
OR - Press ICS reset button (1–2 seconds)
KEY FIELD TAKEAWAY
DO NOT replace ICS first
Follow this order:
- Check hose is factory configuration and have not been lengthened
- Swap pressure sensor hoses (to clear moisture and contamination)
- Fit ICS filter (652063) (to prevent moisture and contamination)
- Only then consider ICS replacement if faults don't clear
Related Resource
- TQ / TQM Fault Codes + ICS LED Guide TQ / TQM Fault Codes (FC Errors) + ICS LED Flash Guide – Diagnostics & Quick Checks: Seeley International Pty Ltd
ICS Filter (P/N 652063)
IMPORTANT NOTE!!!!
If grey silicon rubber hose from pressure sensor on board that goes through divider panel has previously been modified (lengthened) it needs to be returned to the below factory configuration with the short grey hose spigot as per below.
TQM5 MODULATING Gas Valve Non-Condensing
IMPORTANT NOTE!!!!
If grey silicon rubber hose from pressure sensor on board that goes through divider panel has previously been modified (lengthened) it needs to be returned to the below factory configuration with the short grey hose spigot as per below.
TQM6 MODULATING Gas Valve Condensing
