Low RPM with A/C on.

[henry]

Hi guys:

The RPM drops to almost 300 when the A/C is on, I this normal?

Thank You.

Henry.

[racydave]

Sometimes they add a electric stepper motor to the throttle to compensate. They energise when the A/C is on, and are adjustable. If not its a compromise.

[So Cal Mark]

FI Toyotas from the late 80s used a vacuum switch to raise the idle with AC on. It's a simple bolt on addition, just search your local pick a part for an old Toyota

[TulsaSpider]

What motor do you have? is it FI?

[henry]

Thank you for the answers, my engine is FI.

[majicwrench]

Without looking it up, I can tell you that it came from the factory with something to raise the idle when the A/C is on, there is no reason to add anything new. A FI engine has some sort of computer controlled idle speed control, find it and test it. It is the same component that makes the engine fast idle when cold, does yours idle up cold??
Keith

[So Cal Mark]

The L-jet uses an aux air regulator to increase cold idle speed, it won't raise idle with the ac on. I've never seen a Fiat with any device to raise idle with AC.

[majicwrench]

Mark,
That's interesting, I'll have to look into that. I can't imagine a car WITHOUT some way to pick up the idle with A/C on, heck even big monster V8's had A/C kickers.
Keith

[So Cal Mark]

the ac was a dealer add-on, so the FI was never designed for an idle kicker from the factory

[alexGS]

For what it's worth, my Uno Turbo with L-Jetronic also had A/C added by the dealer in Hong Kong, and because as Mark says the L-Jetronic idle valve is a bimetallic heated device active only when cold, the device used to increase the A/C idle speed was just a simple on/off solenoid valve with 6mm (1/4") pipe fittings. One side was hooked into the vacuum/pressure line to the manifold, and the other side hooked to the air trunking before the throttle plate but after the airflow meter. In other words, the solenoid bypasses the throttle.

[henry]

I had to change the Temp Switch today and I found out the RPM aren't changing anymore when I turn the A/C on