Symptoms drivers describe
- Cold or lukewarm air with the heater on full
- Temperature gauge slow to rise or unusually low
- Coolant level low or dropping
- Damp carpets or a sweet smell inside the car
Possible causes
- Low coolant level, often from an unfound leak
- A thermostat stuck open
- Air trapped in the cooling system
- A blocked heater matrix
- A faulty blend motor or heater control
- A failing water pump
What you can do
- Check the coolant level when cold
- Note whether the temperature gauge reads normally
- Do not ignore it — the same fault can lead to overheating
How we check it in the workshop
We check level and system pressure, test thermostat operation and coolant flow through the matrix, and check the heater controls before stripping anything.
Is it safe to keep driving?
Have it checked. A cold heater with a low gauge or lost coolant points at a cooling fault worth catching early.