Q: When I turn my car on it bogs down off and on but when I turn my ac on it will keep doing it worse and then the car starts shaking

asked by on

I turn my car on it bogs down off and on but when I turn my ac on it will keep doing it worse and then the car starts shaking so bad it will cut off. What could be the problem?

My car has 87000 miles.
My car has an automatic transmission.

There are a number of things that may cause the engine to bog down as you describe. The reason this appears to be worse when the AC is on is that the AC compressor requires a bit more power from the motor to turn it when the AC is on. It is likely that the problem exists outside of the AC, meaning that the AC is not causing the problem.

A clogged or failing catalytic converter can cause the vehicle to have poor fuel economy. As you may already know, the catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. In cases where there is too much fuel being provided (i.e. a leaking fuel injector), this may cause the engine to bog down and produce a fuel smell and occasionally, emit a bit of black smoke from the exhaust or cause problems with starting.

Shaking or vibration may be caused by many different things such as faulty spark plugs, poor fuel pressure or misfires. Other things such as a faulty idle air control valve may cause the engine idle to drop below the normal idling RPM which may also cause the motor to shake or vibrate more than normal. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. Anytime a misfire is caused, this causes an imbalance in the motor which will cause the motor to shake or vibrate. Other issues that may cause this type of shaking or vibration might be broken engine mounts or potentially tires that are out of balance or worn improperly. Engine mounts are generally rubber mounted braces that hold the engine in place to the chassis of the car. When these break or become weak or faulty, this may cause the engine to vibrate heavily. When tires are out of balance, as the speed of the vehicle increases, the vibration will become much more noticeable and pronounced. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle using a scanning tool which will more accurately indicate what specifically may be causing this.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. When I turn my car on it bogs down off and on but when I turn my ac on it will keep doing it worse and then the car starts shaking

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: No Crank, No Start After Clearing Check Engine / Security Codes?

A scanner will not cause a no start but the security system will. You will need to have the passlock system codes pinpoint tested to see if the problem is the key or the system needs reprogrammed or the module...

Q: I have the 4 error codes . And I looked them up in the diagnostic book. I was told by a phone representative to ask you

Unfortunately, without the error code numbers this would be difficult to interpret. Please feel free to send us the specific error codes and we will be glad to help you.

Q: Would a faulty front main bearing seal drop oil pressure to the hydraulic lifters?

Hi there. Lifters will tap if there is no pressure to them causing a gap or if the lifters are out of adjustment. Put on a mechanical oil pressure gauge to the engine and check for oil pressure. If there...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...