Idle Drop Problem when A/C comes on

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Miata92-Yellow - 11 Jul 2004 18:53 GMT

Just within the last week or so the idle speed
on on '92 drops very, very low just short of
stalling when the A/C clutch engages.
Prior to this behavior I experienced a small drop
in RPM when the A/C clutch engaged but nothing
like the size of the drop I get now. I've
had the car for over ten years and this is not
the drop I've always gotten in the past.

Any suggestions.

Denny
'92 Sunburst
'02 Vivid Yellow

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Expmiata - 12 Jul 2004 02:12 GMT

>Just within the last week or so the idle speed
>on on '92 drops very, very low just short of
[quoted text clipped - 10 lines]
>'92 Sunburst
>'02 Vivid Yellow

Hi
I was having same problem. Here is what I think fixed it. There is a unit
called the ISC valve.....it has an electrical connection at the bottom of the
throttle body to the right hand side of the ISC valve. It can be tested for
ohms. Ohms should read between 11 adn 14 ohms.

Mine was dead. I got another online at Mazmart.com for about $120 (used) and
viola, the rpms now go back up when AC is running.

~Cissy
<a href="http://members.aol.com/IvaMiata/Krikkit/index2.html">My '90 Mazda
Miata</a> 
I love PC adventure games

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Miata92-Yellow - 12 Jul 2004 03:46 GMT

My RPM comes back up to a good level.
My concern is the much greater drop in RPM,
almost to the point of stalling, before it
returns to the higher normal level with the
A/C engaged.

Will check your suggestion as possible cause.

Thanks,
Denny

>>Just within the last week or so the idle speed
>>on on '92 drops very, very low just short of
[quoted text clipped - 24 lines]
> Miata</a> 
> I love PC adventure games

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Expmiata - 12 Jul 2004 03:47 GMT

>My RPM comes back up to a good level.
>My concern is the much greater drop in RPM,
>almost to the point of stalling, before it
>returns to the higher normal level with the
>A/C engaged.

ok, good luck. Perhaps I misunderstood the problem.
~Cissy
<a href="http://members.aol.com/IvaMiata/Krikkit/index2.html">My '90 Mazda
Miata</a> 
I love PC adventure games

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Dana Myers - 12 Jul 2004 04:24 GMT

> My RPM comes back up to a good level.
> My concern is the much greater drop in RPM,
> almost to the point of stalling, before it
> returns to the higher normal level with the
> A/C engaged.

The IAC might be the issue, but if the idle
recovers, the IAC is probably working. It sounds
like the idle air bleed screw setting might be
improper, perhaps a re-adjustment of the idle
might fix this?

Dana

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