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Guest Message by DevFuse
 

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high idle linked to blower motor


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9 replies to this topic

#1 aa8jzdial

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Posted 22 October 2012 - 08:38 PM

My wifes 2000 Forester, manual transmission with 175k miles run fine unless the blower motor is on. The idle jumps up to 3000 to 400o rpm and will drop to normal when switching blower off.
As winter approaches running without a heater/defroster is hardly an option.
Any ideas?
rick
w mi.

#2 Legacy777

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Posted 23 October 2012 - 03:18 PM

You may want to have the alternator or battery checked. I know when the voltage is low the ECU will raise the rpm to increase voltage and charging.

#3 nipper

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Posted 23 October 2012 - 06:46 PM

There have been odder things....


Good place to start, though the jump sounds awfully high as alt output hits max above 1800 rpm.

What happens when the defroster is on?

#4 The Dude

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Posted 23 October 2012 - 09:16 PM

Do the headlights dim when you turn on the blower motor?

Automotive CPUs are desigend to be very resistant to interference from EMF, but you might give this try. Turn your car radio to an unused spot on the AM band, the FM band will not do. Turn on your blower motor, do you LOTS of VERY loud static?

#5 Rooster2

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Posted 24 October 2012 - 09:38 AM

Prolly worth a trip to an Autozone or Advance Auto Parts store, or similar place, and have them check out the charging system. They don't charge for this, and they will tell you if there is a problem with the alternator or battery.

#6 nipper

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Posted 24 October 2012 - 10:03 AM

If you have a volt meter you can check the charging system yourself.

#7 aa8jzdial

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Posted 29 October 2012 - 08:21 PM

Battery voltage hangs around 13.8 to 14.2.
No am radio noise.
Haven't checked what effect the defroster has.
Maybe tomorrow.
How does that figure in the scheme of things?

rick
w/mi

#8 presslab

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Posted 29 October 2012 - 10:09 PM

Could be a bad ground. Put a voltmeter from the intake manifold to the car body. What are the voltages with the blower running and without?

#9 uniberp

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Posted 30 October 2012 - 11:56 PM

Battery voltage hangs around 13.8 to 14.2.
No am radio noise.
Haven't checked what effect the defroster has.
Maybe tomorrow.
How does that figure in the scheme of things?

rick
w/mi


defroster mode kicks on the AC compressor. AC-compressor-on raises the idle.

#10 Gloyale

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Posted 31 October 2012 - 10:55 AM

I would inspect the hoses from intake tube to IAC, and from IAC to the thottle body.

Idle Air Control valve. IIRC, it's located on the passenger side of the intake. About the size of a sharpie pen, with a couple tubes, and a purple connector.




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