Hello all,

My Audi A4 Sline 2016 has a weird problem which even the mechanic is struggling to diagnose as it comes up with no faults. This is the second mechanic I have taken it to as the initial mechanic said it’s the heater box and that it would be costly(£2000) to replace, but I have had multiple people tell me he’s having a laugh.I have an issue with the blower in the car. It works perfect when I initially start the car when it’s cold and has not been driven for a long time(morning when I go work) it blows air out, warms up as normal, and then after a while(15mins or so) it blows out weak hot air and then then eventually no air comes out from the blower, if you put your hand on the vents it is warm but nothing comes out but can hear something working behind the dash, if I turn the car off and start again it still won’t work. It only works when the car has freshly been started after a long period.

You need to get the car scanned with VCDS. There are multiple flap/motor doors on the B9 related to air con/heating. If one of these modules is fault it could be restricting airflow as you’ve suggested. VCDS will pinpoint the module. Easy one you can do yourself, has pollen filter been changed. These are often bypassed in services, and if it’s original it will be clogged up.

Just to rule out other issues, does engine temperature sit bang on 90 degrees? If that fluctuates there is a different fault.