Overheating And No Cabin Heat

Gauge Rising

Cold level on the expansion tank between MIN and MAX first. A sealed system that wants weekly topping has a weep. On the V6 petrol cars the plastic thermostat housing and crossover pipe go brittle and crust white; that job is A-019. Do not open a hot cap.

• Thermostat: Stuck shut overheats quickly. Stuck open leaves a cold engine and weak or no cabin heat.
• Airlock: After a drain, bleed until both sides of the heater circuit run hot. An air-locked V6 can idle oddly and throw random codes.
• Radiator and fans: Blocked core or a grille packed with leaves, plus a fan that never spins on a hot idle, push the needle up in traffic.
• Cap and sender: A weak pressure cap lets the system boil early. A lying temperature sender makes you chase heat that is not there, or ignore heat that is.

Heater Blows Cold

If the upper radiator hose stays cool while the gauge looks normal, suspect a thermostat that never closes, or a matrix that is blocked or air-locked. Confirm coolant is actually circulating into the heater pipes with the controls on full heat. A sweet smell in the cabin or a wet passenger carpet can be a matrix leak, not only a scuttle drain.

Stop Driving When

Needle in the red, steam, or a sudden loss of level: shut it down. Running hot warps heads and finishes head gaskets. Find the leak or the stuck thermostat before the next journey.