Q: Car runs rough with AC on

asked by on

My car drive perfect without the ac on.as soon as I turn on my ac I feel a vibration on my steering wheel

My car has 119000 miles.
My car has an automatic transmission.

It sounds like you may have a bad AC compressor or potentially a faulty MAP Sensor. When the AC compressor is beginning to fail, this may incur an increased load on the motor as it works harder than usual to turn a bad compressor. This increased load causes the motor to work harder than it otherwise normally would, resulting in the motor overheating.

The Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance. When the computer reads a heavy load signal from the MAP sensor, it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. The computer will then retard (back off) ignition timing slightly to prevent detonation that can damage the engine and decrease performance. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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. Car runs rough with AC on

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: Rear of car makes whining noise.

Howling, whining or whirring noises coming from the rear-end of the vehicle may indicate the need to have the rear differential inspected. Howling under acceleration at various speeds may indicate that the gears are worn out or are out of...

Q: Heat only works when im pressing the gas sometimes

Hi There, I would suggest first checking your coolant level to be sure there is sufficient coolant in the radiator as this is what flows through the heater core which is what generates the heat you fee inside the cab...

Q: My motor sounds like it is forced.

Hello. It sounds like you have a transmission that is slipping from the description you are giving. Some things that should be checked when experiencing slipping symptoms are the low or dirty transmission fluid, clutch problems, failing shift solenoid, or...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.