B6 Passat heater not getting hot.

[scottjenkins]

Hi Guys,

My heater has has started to only heat up when it wants, I can set it onto max heat and it will blow cold and then starts blowing hot maybe 5-10 mins later???

when it does eventually become hot and you decide to turn it cool again that works, but if i try to up the temp again it will only get hot when it decides too.

This happens on long drives I wouldn't expect it to heat up on a 5 min drive.

Any help would be much appreciated!

Thanks
Scott

[RichardSEL]

What car? What year? What miles? When did this start to happen? What was the last work you've had done before fault started?
Have you had a code read? How's your fuel consumption? What does your temp gauge read after five to 10 mins running?

[scottjenkins]

Hi Richard,

passat 2.0 tdi
55 plate
155K miles
fuel consumption is ok
90 degrees after 5/10 mins of driving
only just noticed this issue recently, with it being summer haven't needed the heating.
had codes read 6 months ago - and there was no error.

Thanks
Scott

[RichardSEL]

What is the colour of your coolant?

The coolant now used is pink G12, G12+, or G13 at 50% dilution that gives protection up to -36.4°F (-38°C). These are not backward compatible with the older blue or green coolants. They cannot be mixed. If they are then a thin gel can result, blocking coolant flow through the heater matrix and engine cooling galleys.
Check thread of cap, and thread of coolant tank neck for chalk and remove by running round a small screwdriver blade inside the threads. Check inside cap black sealing ring for any tear. And top of coolant tank neck for cleanliness.

To clear any trapped air in engine and cooling system:
Release coolant reservoir cap.
Start engine.
Place heat control on full.
Wait until temp. indicated is 90ºC (½ FSD = 200ºF)
Check you’ve got coolant being pumped back into reservoir via small hose at side. Leave running for 20mins with occasional blip on throttle.
With protected against boiling coolant hand replace reservoir cap and turn clockwise to click stop.
This has purged air out of heater matrix and system as a whole, if there was any stopping heat up.
The above procedure can often clear any build up of gel if the top up of new coolant to old was only minor.

Any help?