Audi a4 b8 1.8t heater issues

[Mvu]

Hi all

I have a very funny issue, my car suddenly blows cool air when the heater is on a warm setting. So I will put my heater on, say 22⁰C and it will blow hot air, but after a while it will blow cool air. This is driving with a warm engine. Engine Guage on 90⁰C mark and not fluctuating.

Any ideas what the issue could be?

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[Jet Li]

Is your A/C button on/off when that happens?

[Mvu]

Is your A/C button on/off when that happens?

Hi Jet Li, it is off.

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[Jet Li]

Alright, can you check when you car is stationery and idling if indeed the aircon pump pulley is disengaged even with the button showing off on the inside.

Is there any difference when you operate your climatronic manually or on auto?

Normally when your temperature is set to high even with your fan is switched off, you can literally feel hot air coming in when the car is in motion, which means hot engine water is running through the heater core inside the dashboard.

If indeed the a/c is off and temperature is set to high then possibility is that there is no water circulating from the engine into the heater core.

It shouldn't be too hard to solve. Good luck