Heater blows only cold air

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Hi, the heater on my 1.8sci ghia 06 only blows cold air, I changed the thermostat but no change, the two pipes going into the bulkhead never get warm! Any ideas? 

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Few things pulled from a website to look for - 

1. What is the quantity of water in the car? The first thing to check if you experience a cold blowing heater is to check the quantity of coolant in the engine compartment. You should only do this if the engine is cold. The expansion tank collects excess coolant from the radiator. Positioned just above the radiator, this large clear tank has rubber hoses coming off of it and can be found to one side of the engine.  If the amount of coolant is low, you need to top up with water or add an antifreeze compound if need be. In cases where the fluid levels are not low, you should move ahead to check other causes which may be affecting the heating system.

2. Is your thermostat serviceable? A thermostat is one of the core areas that you should concentrate on if your car heating system is not working. If you have determined that you have the right quantity of water and coolant but the system does not heat up, you should consider checking the condition of the thermostat. The dials on the dashboard will help you in knowing whether the thermostat is functioning as required. If your car engine has been running for about ten minutes, the temperature gauge should give you a reading to show that the temperature has risen from the ‘cold’ to ‘hot’. Ideally, the dial should sit somewhere in the middle. In case these readings are not recorded on the temperature gauge, the thermostat could be broken. You should consider visiting a mechanic or service centre for a quick fix.

3. Is there an airlock in the heating system? Airlock in the fluid lines may cause an improper delivery of the coolant to the heating system due to foreign objects. You can fix this problem if your system has a bleed screw or bleed port by adjusting it anticlockwise using a screwdriver. Once the fan kicks in after running the engine, and you hear a hissing sound, this means that the airlock has been rectified.

4. Are there water leaks in the heating system? A leaking heating system reduces the amount of pressure available in the fluid lines which means a low delivery amount of coolant. Some of the areas which you should check for leakage are fluid hoses, radiator, water pump, heater mtrix and the head gasket. A check by a mechanic will help in rectifying any leaks detected which may need repair or replacement depending on the magnitude of damage.

5. What is the condition of the heater and heater controls? The thermostat or the cooling system may be serviceable, but the heater could be broken or clogged. The heater controls could also be cut or stuck, hence not delivering the desired command to the heating system. Check the heater, and the heater controls to ensure that they are in their proper working condition. You can fix the problem if detected or visit your mechanic for a fast fix.

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