rough idle when A/C on and stopped at traffic light.
Jul 20, 2020 at 10:53 PM
Engine idles rough
2003 FORD FOCUS
LILHOBO
- MEMBER
- 1 POST
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Hi,
The most common cause of this is a low idle speed. The vehicle has what is called an idle air control valve. The IAC is responsible for maintaining the engine idle speed. When the added load of the A/C compressor is placed on the engine, the IAC should raise the idle speed to compensate.
Do me a favor. Check to see how low the engine idle speed is when stopped with the A/C on. Also, turn the A/C off and back on to see if you notice the speed increase.
Here is a link that shows how to service an IAC. Take a look through it.
https://www.2carpros.com/articles/idle-air-control-valve-service
If possible, let me know if this is a single or double overhead cam engine. The IAC is located differently. I can get you directions specific to servicing or replacing that component.
If you aren't sure which engine you have, look at the VIN (serial number) at the base of the windshield. The 8th character from the left identifies the engine. Let me know what that digit is.
Take care,
Joe
The most common cause of this is a low idle speed. The vehicle has what is called an idle air control valve. The IAC is responsible for maintaining the engine idle speed. When the added load of the A/C compressor is placed on the engine, the IAC should raise the idle speed to compensate.
Do me a favor. Check to see how low the engine idle speed is when stopped with the A/C on. Also, turn the A/C off and back on to see if you notice the speed increase.
Here is a link that shows how to service an IAC. Take a look through it.
https://www.2carpros.com/articles/idle-air-control-valve-service
If possible, let me know if this is a single or double overhead cam engine. The IAC is located differently. I can get you directions specific to servicing or replacing that component.
If you aren't sure which engine you have, look at the VIN (serial number) at the base of the windshield. The 8th character from the left identifies the engine. Let me know what that digit is.
Take care,
Joe
Jul 21, 2020 at 6:52 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.