My 98 gti mk3 has a 2.0 l it idles fine until I
turn on the a.c. then it idles up an down can
the ac is taking to much load so its causing a power drain that the car has to makup for. this is ussaly caused by a ac pump clutch going bad a fan clutch going bad or a altanator that needs new points. i ussaly recomend keeping the altanator the car has already and get it rebuilt i went threw 4 of them due to improper rebuilds i woulda had mine rebuilt but the core was cracked and the inner copper rings were warped and rusted out. so no chance of rebuild for mine. this is the ussal causes from my perspective.
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