Mk5 'Econ' mode on heaters coming on without being pressed

[VAGMAN2]

As above, I have a Mk5 Golf with manual aircon controls. I've noticed over the past few days that sometimes the ECON mode button is lighting up, not having pressed it, when you turn the blower mode dial ie from Windscreen t main vents.

Also (and this may/may not be connected), the hot air setting doesn't seem to be getting as warm as it once did. It takes a good blast at max temp, max fan speed and on aircon mode to get hot air blowing out.

Any suggestions....?

[portovechios]

Does you engine temp get to 90 and stay there?

[VAGMAN2]

Yes - engine temp gets straight up to 90degC and stays put! The coolant hasn't also been changed, so I can rule out airlock issues etc.

[kite]

You could have low aircon pressure

using tapatalk from a phone smarter than me

[VAGMAN2]

I've got VAG commander so probably worth scanning over the A/C module then. Low a/c pressure would be due to a leak in the system/low refrigerant level?

[kite]

Low level or a failing pressure switch

using tapatalk from a phone smarter than me

[portovechios]

Not ness a leak, aircon r32 needs topping up several times during its lifetime dependant on its use

[phil miller]

if your 'econ' button has been pressed (to light up) when you turn it to the windscreen it will put the light out (switches AC on to clear the screen) then when you turn it back to say on your feet the econ light will come back on, with the light on press the switch (light goes out) and turn it thro the different positions and you will see the light will stay off, nothing to worry about and 100% normal mate

[radox]

I agree with phil miller that the ECON light will temporarily go out if you move the air distribution dial to the windscreen position. However, I believe the ECON light does come on by itself if the control module decides there is a fault in the system. This would tie in to what you said about there being another problem. I would check the control module for fault codes.

Hope that helps,
Stuart
http://www.stuartdalby.co.uk/vwgolfmk5

[VAGMAN2]

I'm not sure if this is connected to the issue, but....

When I open the coolant expansion tank cap, there's a big whoosh of air and coolant level rises dramatically (lets say by 2cm). It was even doing this if the car had been left for a couple of days > Airlock in the coolant system?

Just as a quick attempt at a fix, I took the cap off yesterday, ran the engine at high revs for a 2-3mins yesterday - some bubbles did come up in to the expansion tank. When I removed the cap again, several hours later, there was no whoosh of air.

So perhaps the heating issues are down to air in the system? If so, what the easiest way to bleed out air?