MK4 Golf gti Jerks!

[performancevw]

Hi I am new to this forum and I am looking for some answers/suggestions/advice about mk4 golf gti 2.0 8v 53 plate 70,000 genuine miles. When I turn on the heater inside, the car jerks every now and again while driving no matter what speed, the jerk only happens for about a second (no more) and it feels like its hesitant in power while that jerk happens for a second. Turn the heaters off and no more jerks. Turn it back and it will start the jerk. Also, the inside heater fan makes some noise when turn on and goes high and low itself so I have to adjust it manually by pressing the button. Could someone tell what is this and why is it happening? or where the problem is? Many thanks.

[Mike671]

You got climatronic? As If set on high fan Wont speed up straight away and takes a few seconds to speed up this is sometimes as it knows temperature of the air is not warm enough compared to what's set on display. Also when turning heater on it causes extra load on engine so throttle body should open up more is it happening like it will stall? Maybe worth checking throttle body as could be dirty and sticking

[Hulmie]

its cos when you turn the heaters on it will zap all the poiwer the 2.0 8v engine produces 

[gavgtiturbo]

its cos when you turn the heaters on it will zap all the poiwer the 2.0 8v engine produces 

You could actually be on the right track there Hulmie,the battery may be on the way out or the alternator may be weak and the extra bit of power needed for the heaters may be cutting engine power.Id also check the battery earth too.

[james18t]

If you have climatronic, make sure you have it set to Econ, as I think if it's not on Econ it uses the air conditioning which will sap a lot of power from the engine. Mine has the same jerk effect when I turn my air con on.