Q: Fast Idle does not activate when A/C Compressor engages.
Car idles normally at 750 rpm. However, when idling (such as at a traffic light), and the A/C Compressor engages, idle remains at 750 rpm (engine struggles) and does not advance to 1000 rpm, like it should.
My car has 70000 miles.
My car has an automatic transmission.
Recommended Services
| Clean Throttle Body | $109.17 - $370.59 | Get a Quote |
| Car idle is rough Inspection | $94.99 - $114.99 | Get a Quote |
The idle is not supposed to increase in speed when your compressor engages, rather the throttle plate should adjust at the same time the A/C engages to maintain the same RPM at idle. This will keep the idle the same with A/C on or off. If the idle drops below 750 and then jumps real high then this is a problem and should be looked at. The throttle plate, which controls the idle speed, may need to be cleaned or inspected.
The statements expressed above are only for informational purposes and should be independently verified. Please see our
terms of service
for more details
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
What others are asking
Car cranks but no start or spark
From what you've described, you may have a bad crankshaft sensor (https://www.yourmechanic.com/services/crankshaft-position-sensor-replacement). You'll know if this is the case once you run a scan test to get sensor data. The sensor may not be sending a crankshaft signal to the...
Why do I hear chattering noise from under my SUV while driving?
Hello there, thanks for writing in. I'd be happy to help. Squeaking and chattering noises can be caused by many things. Common causes of these symptoms are worn suspension or steering components. If any steering tie rods or suspension bushings...
my power steering blocks each time I have to maneuver in a parking, not when I'm just driving
If by "blocks", you mean the wheel turns smoothly then at some point in turning it, the wheel suddenly goes stiff and is hard to turn, it it a common symptom of GM products of that era having a bad...
High fuel consumption
The Space Gear used both 4 cylinder (2.4L) and 6 cylinder (3.0L) engines and there was also an AWD (All Wheel Drive) version, not to mention diesel versions. Consequently, the curb weight of the various versions of the vehicle ranged...
Independently decelerating until car stalls when driving greater than 40 mph. Plus there is high RPM's with acceleration and won't always start in the mornings.
Hi there. Check to see if the fuel pressure on the fuel rail and see if the fuel pressure is around 45 to 65 psi. Run the engine up to a higher rpm and see if the fuel pressure drops....
My wife's oil cap blew off and oil got all over the engine. Car has no power. When I hook up jumper cables it will rev up but wo
Hi there. This symptom can be cause by a plugged PCV system (https://www.yourmechanic.com/services/positive-crankcase-ventilation-pcv-valve-replacement), or more likely severe blow-by, where combustion gasses blow the oil out of the crankcase and up to the valve covers. This could be cause by broken...
AC blows cold only when driving
Hi There, Based upon what you are describing it sounds like the AC condenser cooling fan (https://www.yourmechanic.com/services/ac-condenser-fan-replacement) is not working properly. As you are driving down the road, there is generally enough cool air blowing through the condenser without the...
My car wont go above 40 mph,has a burning smell,and has a noise?
Hi There, What you are describing sounds like you may have a clogged catalytic converter. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When the catalytic converter is...
Car has been misfiring since fixing the exhaust leak but now keeps dying after 10 mins
Hi there. If more than one cylinder misfires, this will increase or decrease the revolutions per minute (RPM) of the crankshaft. If that increase and/or decrease is more than 2 percent, the Powertrain Control Module will store the P0300 trouble...
Related articles
The Best Used Cars to Buy for Long Commutes
Most Most of us are faced with the prospect of commuting back and forth to work on a daily basis, but some have a much longer drive than others. When it comes time to buy a car, you need to...
Symptoms of a Bad or Failing AC Control Module
Common signs include inconsistent cooling, out-of-date software, and uneven air distribution, since the module controls the whole AC system.
How Long Does an AC Control Switch Last?
Every Every year, vehicles become more and more complex, with computer components replacing mechanical parts. This is very apparent in your car’s air conditioning system, which relies on an AC control module to deliver the ideal heating and air conditioning...
Browse other content
Estimates
Services