Need help with heater

[leeclark]

Hi guys, my hot cold heater control has been very stiff to turn. The cold air was coming through nicely and air con was working well but after turning switch to cool things down today it suddenly became a bit easier to turn and now the heaters are stuck on full blast no matter where the switch is . The heater fan switch works as it should and also the one to the right of that that operates and diverts the air through vents on windscreen and floor is working ok. Can anyone help?

Many thanks

Lee

[leeclark]

Thanks guys