heater fan not blowing when air con on

[dazzcupra]

i will try and explain this the best i can.
when i press the button for cold air (snowflake) i do get cold air but if i try to turn up the blower the air still only trickles out, but when i turn the snowflake off, i.e no cold air , it blows fine, whats wrong??

 

[LEE69]

Is the air con charged up?

 

[matt-drummer]

It's climate control, maybe the fan has to blow harder to reach the requested temperature when the air con is not selected? Have you tried switching the climate control from automatic to manual, then you can have the fan blowing harder with the air con running?

 

[dazzcupra]

no. it happens in manual and auto,temp set to low and the fan blower to max, i.e all the bars showing and lots of air coming from vents. turn on the air-con snowflake button and its just a trickle of air, its very cold but no force

 

[Muttley]

In the same circumstances, mine blows more strongly with the cooling button (snowflake) engaged.

I also noticed that the engine note changed as the compressor cut in and the engine reacted to the load. The low speed fans cut in as well. Quite a noticable change in the noise from the engine compartment (at idle, sitting in front of the house).

Thinking about it, if the temp is set to LO then we might expect the fan to blow harder with cooling on, to get as cold as possible. The cabin air blower speed is set by a resistor pack on the bottom of the fan housing, electronically switched when climate control is installed. Full fan speed = no resistance in series with the fan. Maybe your full speed connection has gone bad (worn wire, dirty or loose connector, or possibly a climate control module fault).

The blower should be in the dash, behind the glove compartment. Resistor pack is on the bottom.


VAG-com can read the fault codes for the air conditioning system, I'd recommend using this to find out what faults are being reported.