Idle with AC on below 6000 rpm

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Idle with AC on below 600 rpm

I was stopping at a traffic today, AC was running when all of a sudden, I can feel the brake release a little leaving my foot pressing down more and the rpm going down a little below 600rpm and then, it went up to 800rpm where it should be when the AC is on. When I accelerated, the rpm was revving high going from first gear onward and it was back to normal again. On the next traffic light, it happened again, rpm going down below 600 and back up around 800 while the AC was on. Is this normal or should I be worried? Thanks, guys.
 
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my cruiser is doing the same...rpm dropping below 600 rpm and then up to 600 rpm when i stop. or when i'm warming it up. i know the idler needs to be checked out because it's sort of wobling and i've also been told the tensioner pully needs to be looked at. you might want to give it a look.
 
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I just bought my baby, 94 LC about 3 months ago and this the first I have turned on the AC being that warm weather is here. Thanks for your info. Now, I can relax.


Just to clarify:

With the A/C on, the rpm's should cycle between the normal (A/C off) engine idle (~600rpm), and the higher A/C "idle up" when the clutch/compressor is engaged. (I forget exactly what rpm that should be.) Basically the same as a home window A/C unit turning itself on and off to maintain the desired temp.

Two things that would indicate a problem:

1) With the A/C on, the rpm's sometimes dip *below* the normal (A/C off) idle speed.

2) With the A/C on, the idle is *always* higher than the normal (A/C off) idle speed. This would mean the compressor is always engaged, because it can't cool the air sufficiently to cycle on/off. Unless it's a *very* hot day, this would usually indicate an insufficient refrigerant level.

Basically, A/C idle cycling is a good thing; it means your system is doing well and is up to the task of keeping you cool. :) So yes, it sounds to me like your system is fine and you can relax.

Curtis
 

Tapage

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Correctme if I'm wrong .. but if you set your AC to the max blower speed ( HI button ) your compresor never going to shutoff .. ( sure you do coz outside it's really hot ! )

I saw AC cicling proper in 1 or 2 positions ..
 
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Correctme if I'm wrong .. but if you set your AC to the max blower speed ( HI button ) your compresor never going to shutoff

Should still cycle unless it's *very* hot out. Probably not when the rig is standing still though (the A/C works much better at higher rpm's), and definitely not as often as when it's cooler out or the blower is on a lower setting.

Curtis
 

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