The ac puts a load on the motor because it takes effort to use the compressor. Think of it like slightly stepping on the gas. Then the idle goes up. How does this factor in..the defroster uses the ac compressor to dry out the air. I bet the ac would make the idle go up as well. The 55watt hid system is probably junk. 1 Answer. When the A/C is switched on the engine ecu increases the idle speed by a few hundred rpm to make sure the engine does not stall and keep a "smooth" idle. This is normal. Also, the A/C system can demand some 10bhp or so during its operation - which is why some people will switch off the A/C when doing an overtake for example. You can configure an input to detect when AC is requested, and select an output to drive a relay activating the compressor clutch. The settings are not hard to find - Startup/Idle and AC Idle up. You can specify high load conditions to switch off the compressor, and idle up delay so the compressor is activated after a short delay after idle In the end of the YouTube video, when you open and close the electric roof with the air conditioner running, it becomes quite unstable. I'm wondering if it's possible to turn off the air conditioner compressor when opening and closing the electric roof. I'm trying to figure out if it's possible to digitally input the roof switch to the link. Here is a verbal summary of how I did it: 1. Make sure the engine is cool because it is in an awkward area so you don't wanna get burned. 2. Remove the top half the air filter box and disconnect the electrical and other rubber hoses so that the plastic/rubber intake manifold can come out easily. 3. Make sure the air cleaner is ON when adjusting the carburettor--the engine expects it to be there. Turn the small Volume Control Screw in all the way - GENTLY PLEASE. It is a needle valve, and you don't want to enlarge the hole by forcing it home. Now unscrew it 2.5 turns. Checked the IAT sensor and it's working perfectly. My theory is when the IAT is giving a false value (-38F when disconnected) the PCM goes into a different operating strategy that ignores what ever it is that is making the idle surge. Again, it's surging by changing the spark advance, changes it from 17-7*. chris: we're getting the AC Idle Up SOLENOID confused with the AC Idle Up DIAPHRAGM. The screw that adjusts the idle speed when the ac is on is located under the diaphragm, which is mounted to the front of the carburetor. The solenoid, which is an electrically actuated vacuum switch, doesn't have an adjustment. Hope that helps. Step 5. Install the new idle air control valve. Align the mounting holes on the valve with the mounting holes on the throttle. Thread and tighten the screws. Then, reconnect the electrical connector and reconnect the battery. References. The idle air control on an Isuzu Trooper is a valve that opens and closes to meter the air flowing into the Following procedure was followed to clean the throttle body and IAC valve: Throttle body was cleaned using a throttle body cleaner whereas sea foam was used to clean the IAC valve. New gaskets were used while re-fitting the IAC valve and throttle body to ensure air tight installation. c9LM.