When having trouble getting heat, after replacing the thermostat and flushing the radiator, my first thought would an air pocket. The cooling system should be bled anytime coolant is drained. This should get any air out of the system. If you are certain the thermostat is opening (both upper and lower radiator hoses will be hot and pressure released) then you might consider a new pressure cap. The thermostat should open between 180 and 220. You can use an infra-red temperature gauge to rule out a bad dash gauge reading. Good idea when having trouble getting heat is to make sure the coolant level is full and the thermostat is working.
How to bleed engine cooling system
- Select maximum heater temperature and blower motor speed settings. Position control to discharge air at A/C vents in instrument panel (04320) .
- Start engine and allow to idle. While engine is idling, feel for hot air at A/C vents.
- CAUTION: If air discharge remains cool and engine coolant temperature gauge does not move, engine coolant level is low in engine and must be filled. Stop engine, allow to cool and fill cooling system as described.
Start engine and allow to idle until normal operating temperature is reached. Hot air should discharge from A/C vents. The engine coolant temperature gauge should maintain a stabilized reading to within the NORMAL range and the upper radiator hose (8260) should feel hot to the touch.
- Shut engine off and allow to cool.
- Check engine for coolant leaks.
- NOTE: When engine coolant level indicator flashes, approximately 0.946-1.416 liter (1-1.5 qts.) of coolant mixture can be added to the degas bottle after a proper engine coolant system refill.
Check engine coolant level in degas bottle and fill as necessary.
Rule out the cooling system when having trouble getting heat
Sometimes the cooling system isn’t the problem. Instead the problem may be in the ventilation system. Make sure the cooling system is full and the engine is at operating temperature. Both heater hoses should be too hot to hold on too. This means the heating part of the system is working properly. Concentrate on the mode door actuators and control head.