2007 Saturn Vue rough idle
I recently bought this vehicle. Took it for an oil change. Battery tested poor. They advised me to replace the battery before winter. 351 cca. With this lovely Indiana weather, I have used the heat and ac. I have noticed in park with either heat or ac on, itll start to idle rough and a fan kicks on. When i turn the heat or ac off, the idle goes back to normal. Could this be caused by the bad battery? I was thinking either that or alternator. Im gonna take it to test the alternator and see if its throwing any codes. Anyone have any tips, suggestions, or advice?