Idle goes up and down when aircon is on

That is most likely caused by the Idle Air Control solenoid.

Sounds like the compressor is failing or seized (for the air con). This would put extra pressure on the system. It could be another fault with the air con system like the solenoids not opening up to allow the flow of gas in the system.

yes it sounds like eithor you have a vacuum leak or your idle air control motor is out or going out test the iac motor too see if that the problem with a small jumper cable hope this helps

Depending on whether your car is Injected or Carby induction, The aircon system has an IDLE UP circuit which is supposed to raise the Idle while the Aircon Compressor is engaged. The Compressor cycles on & off to charge the system pressure as required. The Idle up system typically uses an IDLE UP SOLENOID which is usually mounted directly on the throttle linkage at the Carby or Throttle body itself, or a Vacuum Solenoid which switches vacuum to a Diaphram which is connected to a linkage on the Carby or Throttle body itself, or a Vacuum Switch which ports air into the throttle body to raise idle (This type on injected vehicles only). It sounds as if the IDLE UP system has failed or is not adjusted properly. Revving the engine spins the compressor faster thus charging the system sufficiently to dis-engage the compressor, which in turn removes the load from the engine, allowing it to idle again. A simple way to test is to disconnect the Aircon clutch wire (make sure it cannot fall into belt) & switch on the Air with the engine running. The RPM should raise typically around 300 RPM. If it doesn't the IDLE UP is not working. Hope this helps.

It could be a part called the Idle control Valve. It regulates the Idle speed and keeps it smooth. If it is choked up with carbon gum or the little motor inside it is faulty then it will not allow enough air too pass for smooth idle. When you put your air con on the engine is under more load because it has too turn the aircon pump so it will stall. Also you have a little device on aircon cars that raise the idle a little to compensate for the extra aircon load. If this is not working it could be that.

can y tell me what enigne size ?

check air cond. pump to ensure it is not locking up when engaged (when pump clutch engages) likely is pump issue

what do expect with an auto around town and air con on as well

because the aircon and the heater make the altinator work harder
now if its stalling or so just get the idle put up a bit
if it aint it will be ok

Hi,

In most cases, when the A/C compressor is activated, there is likewise a solenoid that is activated. This solenoid is mechanically couple to the throttle and basically increases the idling RPM . This is to compensate for the additional load that the A/C compressor puts on the engine. If this solenoid is defective or the connector detached, then it will not compensate when compressor is active. Then your idle goes down and the probability of a stall increases.

Slight increase in temperature as compared to other vehicles maybe due to:
1. improper mix of water and coolant;
2. defective or delayed opening thermostat;
3. clogged radiator tubing;
4. leak in the engine cooling system;
5. engine using higher octane fuel or improper oil;
5. engine in need of a major tune-up.

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

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