Check out my social media!!!!!Here is a new video from the first video i did and had a really annoying music i learned from my mistakes and recreated this ne There are two settings on your thermostat to control the fan – auto or on. AUTO means that the fan turns on automatically only when your system is heating or cooling air. Once the thermostat reaches the desired temperature, the entire system shuts off until the next cycle. ON means that the fan is constantly on and blowing air when your HVAC Ford's instructions on how to adjust the idle speed for engines with electronic fuel injection (EFI). D. Digger84. 20717 posts · Joined 2013. #2 · Jun 18, 2020. That screw is a stop for the throttle body butterfly but was not intended as an idle adjustment. The idle speed of engine is controlled by the PCM but its moment to moment adjustment of the idle air control valve. Sent from my iPhone using Tapatalk. RPM up and down is due to a/c compressor engaging. if the rpm drops too low, a/c compressor disengages. observe your idle speed with engine warmed up, turn on airconditioner and adjust the idle compensating vacuum diaphragm adjustng screw underneath the carburetor to the same rpm when a/c was off. that should correct your rpm problem. This is normal -- the AC compressor is a load on the engine. Once the computer detects the new load, it commands a higher idle speed to compensate, and the idle speed should return to normal after a moment. If the problem continues to get worse or starts stalling the engine, the compressor may be on its way out. 1. Irregular idle speed. One of the most common symptoms commonly associated with a problematic idle air control valve is irregular idle speed. The idle air control valve is programmed to regulate and maintain the engine idle speed at a constant rate. If the valve fails or has any issues it can cause the idle speed to be thrown off. 101 posts · Joined 2005. #8 · Sep 14, 2006 (Edited) Darktide said: the easiest way to test for this problem is to spray carb clean around the intake manifold. my altima shakes on idle, too. and the rpm is not steady. i changed out all my motor mounts and tranny mount last summer. an8NCh.