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Why does my engine get loud when I turn on the AC?
Your engine is under a heavier load when you run the AC. So if you turn on your AC and hear a rattle, it may mean you have a failing or bad: AC compressor. Rattling or your car air conditioner making loud humming noises which get worse as you accelerate can both be signs you need to replace your AC compressor.
Why does my car idle high when AC is on?
If the air conditioning is not performing well, the engine might be surging because the system is undercharged or overcharged. If it is overcharged, the load imposed by the compressor will be excessive. If it is undercharged, the AC pressure switch may be cutting the compressor on and off in rapid succession.
Why does my car RPM go up and down when AC is on?
The AC system has a low side pressure switch that engages the compressor at approx 50 lbs. When you hit the AC switch it sends a signal to the PCM ( powertrain Control module) to increase RPM ( sent to the Idle Air Control valve) to compensate for the added load on the engine due to compessor and fan draw..
Why does my car idle rough when the AC is on?
Basically, the IAC allows a certain amount of air to bypass the throttle plate. The extra air enriches the air-fuel mixture during a cold engine start. It also helps increase engine speed when an extra load is placed on the engine, for example, when you turn on the AC or defrost system.
Do you turn on the a / C at idle?
As a rule, you turn on the A/C at idle. The system will automatically bump your idle up so not to stall or bog the engine down. I think there’s a couple of things in play here. What year are we talking about?
Can a 4 cylinder engine have a bad idle?
On a 4 cylinder engine, the idle is usually not that great anyways but if yours seems worse than the norm, might want to get that straightened out because the A/C puts a pretty good strain on the engine and if it struggles as it is, the added challenge of A/C is gonna bog the hell out of it.
What’s the idle speed of an extreamly without a / C?
In park without a/c is about 1500. with a/c in park it hardly drops at all. In drive without a/c it idles a bit below 1000. with a/c in drive it gets slightly lower. So, 600-700ish? 1500 is high for an idle.