QuestionQUESTION: After driving 10 plus miles at highway speeds, when slowing down the air conditioner stops blowing cold air, goes to resurculate, and the idle goes up to 1400 rpm. Turning the ignition off and restarting engine corrects symptoms until highways speeds and slow down.
ANSWER: YEAR and MODEL and ENGINE SIZE of vehicle ??
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QUESTION: 1995 cadillac concourse with the 300 hp engine - northstar
ANSWER: Check the computers for CODES.
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QUESTION: There are no codes, car has been tuned up, air conditioner serviced and no change. problem has been ongoing for over 2 years. Have had service idle control system but repair center could not identify a problem.
ANSWER: On the drvers information center there is no SERVICE IDLE CONTROL SYSTEM message.
What was the CODE that appeared or may still appear if you check the codes ?.
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QUESTION: Sorry I have not better described the problem, guess I thought you were psychic.
The driver information center has from time to time displayed SERVICE IDLE CONTROL SYSTEM - 107. My mechanic was unable to find any codes as the error resets itself usally within 10 miles, before I have be able to get into see him. The same is true of the "service engine soon" light. The car passed california smog with no problems. I have cleared the codes and have had the problem reoccur but no codes
ANSWER: As soon as the check engine light appears check the computer for CODES.
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QUESTION: I do not think you understand, the problem is everyday and the check engine light is every month or so - - - I am trying to fix the problem now - the air conditioner not working all the time. Do you have any guesses as to where to start. We used to be able to fix things without computer codes.
Thank You
ANSWER: Not any more. Without the computer code the possibilities are endless.
Like I said previously there is no message that says: SERVICE IDLE CONTROL SYSTEM - 107.
I can e-mail you the whole list of display notices. E-mail me at: onlineautohelp@msn.com.
Anytime the check engine light comes ON in 99% of all cases there is a fault CODE stored in the computers.
The only thing that I can think of is that the diode down at the 2 wire connector for the AC compressor clutch is either detached and or faulty which will cause this intermittent check engine light.
I can also e-mail you it's location.
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QUESTION: I guess I will have to wait until I can find a code - My auto is a 1996 Cadilac Deville Concourse, not a 1995, and the manual on page 2-80 shows the message I have seen as Service idle control system - 107 description is A problem with idle control has occurred when this message displays. Bring your vehicle to your Cadilac dealer for service. Sorry I mislead you with wrong model year
AnswerDoes the word STRANGLE come to mind ?.
OK, What you have is a difference in the PZM (Body Computer Module) commanded idle speed and the actual idle speed of the engine via the Class 2 serial bus line from the POWERTRAIN COMMAND MODULE (PCM).
Has anyone tried to adjust the idle speed of the engine via the minimum idle set screw on the side of the throttle body and or can the gas peddle be felt bouncing back and forth as the car slows down if you just barely rest your foot on the gas peddle ?.
There are several possibilities that need to be checked.
1. Do you know how to obtain the CODES from the computer ?.
2. The idle speed has been manually misadjusted via the minimum idle set screw as said earlier.
3. The IDLE SPEED CONTROL motor is mis-adjusted.
4. There is a vacuum leak somewhere in the vacuum lines and or the intake manifold which would explain the AC going to the wrong vents.
5. The throttle body where the air enters the engine and both sides of the throttle plate are gummed up with a blackish residue that needs to be cleaned off using an aersol spray can solvent as the throttle plate is not closing all the way due to the residue buildup.
6. There is an internal fault of the BODY CONTROL MODULE (PZM).
The easiest way to find the fault is with a scanner in order to be able to monitor the bus line from module to module.
I would try cleaning the throttle body and throttle plate area and then follow the procedure for checking the actual engine idle speed in the manufacturers factory service manual in VOLUME 1 on page 6C-41.
tom
