Whats going on with my heating?

[Degudodger]

Gents,

Over the last four or so weeks my heating has become tempremental to say the least!

The heating acts normally for the first 30 minutes then starts to cool down to the point where i have to whack the heating up to 28c to get any heat, then it comes through hot. Think nothing, nothing HOT.

Couple of points
- The coolant temperature reaches and remains at 90c after approximately 10 minutes of driving
- For the first 30 minutes the heating works with out fail
- The coolant hasn't been changed recently and the level is between the Min and Max point

Apart from the obvious cause being a sticking thermostat what else could be the problem?

[bobsgolf]

You state the heating is not working correctly ?
What type of heating is fitted to your car
Fully automatic ( like a gti ) climatronic. Or non climatronic

I big thing people don't understand is how climatronic works
What happens is you select  the fan speed and the direction control and water temperature
You adjust the temperature control to the req temperature and the cars heater control will adjust the amount of water that goes in to the car interior heater to maintain the exact interior temperature that you have selected .once the interior is up to the temp ,it will adjust the setting to maintain the temperature you have selected . This might give you the impresion that the heating has cut off , as it would be on full heat till the interior gets up to temp , it backs of the heat once temp reached , if the temp drops , the heat level would increase again . This is semi automatic heating
The golf gti has fully automatic heating , some gt speck cars have this type of heating as an option .

[Degudodger]

Hiya Robert.

Sorry i should have said  

I have the the manual non Climatic air conditioning.

If i have the airflow on directed to the front footwells and windscreen after 20-30 minutes i can feel the air getting cooler to the point where i then have to max out the temperature gauge to 28c to get and heat thou.

[bobsgolf]

evening
i think you need to go back to basics
does the temp guage go up 1/4 mark within 3 miles  and 1/2 within 6 miles , obviously less if the distance is in town , basicaly 5 to 10 mins to heat up fully
does the temp remain at that temperature for the rest of the journey , if it does then i would doubt the thermostat sticking open as the temp would go back down again if stuck open 
Is the cooling system being presurised ? hydrocarbons in the cooling system , resulting in a air lock , = loss of heater
you state this is not the case , with the fact the level has never moved
if their was a choked matrix or a waterpump failure it would not be ok for 30 mins
compair the inlet and outlet pipe temp after 10 mins then after 30 mins if after a run the inlet is roasting and the outlet is cool may have climatronic & the water is being shut off as the interior is up to the temp, you have pre set ,or a possible fault, with the valve , its hard, when you are not their to see whats hapening ,
is the heater cool, or stone cold,  luke warm  ,or just warm after a run , if it is blowing stone cold air then you have a issue if it is cool then it is probably trying to maintain the temp at your level

[bobsgolf]

good evening


just a quick note
have you had your car out for a decent run yet to re check your heater fault ?

[OLLIE_JETTA_MK5]

Gents,

Over the last four or so weeks my heating has become tempremental to say the least!

The heating acts normally for the first 30 minutes then starts to cool down to the point where i have to whack the heating up to 28c to get any heat, then it comes through hot. Think nothing, nothing HOT.

Couple of points
- The coolant temperature reaches and remains at 90c after approximately 10 minutes of driving
- For the first 30 minutes the heating works with out fail
- The coolant hasn't been changed recently and the level is between the Min and Max point

Apart from the obvious cause being a sticking thermostat what else could be the problem?

Hi mate , I have a similar problem , my car will only blow hot air at settings footwell and footwell/screen , no faults on vcds so I took it to my local vw specialist who said the flap on the air con unit is not opening on certain settings ( face and body ) he said its a common fault that the flaps get stuck and the motor for that flap fails , only fix is a new aircon unit and 6hours labour , close to the 1000 Mark , so ill just put up with no hot face I think lol