My AC/Defroster Causes My Car to Stagger

John Paul, aka “the Car Doctor,’’ answers readers’ car-related questions.

By John Paul

Less than a minute to read

Q. Recently when I use my defroster/air conditioning my car starts staggering/chugging pretty badly. Any thoughts as to what this might be? It’s an old but well cared-for 2000 Neon with 140,000 miles, without any others problems.

A. The air conditioner puts additional load on the engine. If the engine is starting to miss-fire this additional load may be exacerbating the condition. To find the problem a technician will test both the ignition system and fuel system. A worn spark plug or faulty fuel injector could be the problem.

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