Quote Originally Posted by jcal68 View Post
hmm. . .so this means the idling is okay when A/C is off.

Try this:
1. The idling should increase when you turn on the A/C. The compressor consumes engine power necessitating idling increase.
2. The thermostat controls on/off of the magnetic clutch of the A/C compressor (you will hear it click). AND ALSO controls a small solenoid valve.
3. The magnetic clutch is okay because it lowered the engine rpm.
4. The small solenoid valve controls the vacuum. The source of this vacuum is also from the carburetor. We use this vacuum to assist other systems. In this case we use the vacuum to increase idling when your compressor activates.
5. Vacuum from carburetor connected by small hose to solenoid valve then connects out by a small hose again to a diaphragm.
6. This diaphragm is the one that increases idling by simulating as though you are stepping on the pedal.

Troubleshooting is by isolation.
1. Check your hoses first. Busted hose mean no vacuum transmission. Suck on the hose leading to the diaphragm. You would see the idling pulley move if okay.
2. Also check the other hose for leaks.
3. Check also the solenoid valve if it open to deliver the vacuum to the diaphragm.

If you still can't find the trouble then better call a qualified mechanic.
In my case, my Mitsubishi lancer gli (4GI5 MULTI-ECI) decreases to a very low RPM after traveling several kilometers. After I turn off the engine and after few minutes turn it on again, the RPM is very low that the engine will die. What would be the problem and what would be the possible fix? Thank you.