hey all it was a bit chilly this morning and i flicked the heater on and it didnt work the car was at half temp and i hit the climate control and cranked up the heat and it was blowing cold air what could be wrong??
cheers
If the pipes inside the car are boiling hot, then the heating system (coolant circulation wise) is working correctly. Sounds like one of the sensors may not be giving the climate module the correct reading, for example, the outdoor ambient sensor might be saying its 35 deg C outside, and the system takes that into account thinking that heating is not required. The other thing is that it could be the air mix door not working properly, therefore only allowing cool air in, and completely bypassing the hot air created from the heater circuit. If you run a diagnostic code check on the Climate system you should be able to work out where the problem lies.the system relies on information from the sunlight sensor, air con evaporator sensor, interior temp sensor and exterior temp sensor in order to create the temperature specified on the system. Say its 5 degrees outside, and you have the system set to 23 degrees, the system uses the info from the exterior sensor and interior sensor and sunlight sensor to deduce that its colder in the car than the temp specified on the display. Therefore it will use a large amount of air that will pass through the heater core and through the warm air section of the air mix door. Once the temperature of 23 degrees is reached, the air mix door will change the ratio of hot and cold air from full heat to a mix of mainly fresh outside air but still with a little bit of warm air to maintain your desired temperature.
In regards to the AUTO mode, this allows the system to automatically turn the A/C on if the cabin becomes too hot, as well as automatically selecting which vents are required for your set temperature, ie when heating the air is directed at your feet, then as the cabin warms up you get warm air on your feet and cool on your face, and then when the cabin reaches the set temp it will only blow air from the face vents. In addition to this, the fan speed is also automatic, so when heating when cold the fan will come on at a high speed once the coolant has warmed up, and then gradually reduce speed as the cabin warms up.
The best way to run the system is to switch it into AUTO mode, and then turn off the airconditioning, as its just a waste of petrol especially in winter. That way the system still keeps every other mode in automatic, except that it won't use the airconditioning at all. When I had my Berlina this is what I used to do, and then in Summer, say on days over 28 degrees I would just run the AUTO mode, which worked very well, and even with the airconditioning running, it didn't make that much difference to fuel usage, as the airconditioning only cuts in and out to maintain the set temperature, it doesn't run flat out.
Sorry for the long post, but hopefully that gives you an insight on the system. Perhaps try running the AUTO mode, and turning off the A/C and see how you go. MANUAL will appear on the display, but the fan icon will have an A next to it.