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Joined: Jun 2003
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CEG\'er
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CEG\'er
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My car (95 mtx I4) idles just a little bit lower (bout 250) when the defroster is on full. When i turn it down it goes back to normal idle. Is this normal or is something wrong??
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Joined: Aug 2002
Posts: 34
New CEG\'er
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New CEG\'er
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This is due to the defroster drawing electrical power. The alternator puts a heavier load on the engine which slows it down (similar to when the ac is turned on). A small change in rpm due to accesories being turned on is usually normal.
'96 Mystique GS 2.0L ATX
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Hard-core CEG\'er
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Hard-core CEG\'er
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IIRC, the a/c comes on when the defroster is on. The a/c is probably putting the load on the engine.
95 Contour Zetec, ATX (wrecked, sitting in the barn)
95 Mystique Zetec, MTX
2000 Taurus SEL 3.0L Duratec
1994 Crown Victoria LX 4.6 V8
1993 Chevy Silverado 4.3 V6
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Joined: Sep 2003
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CEG\'er
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CEG\'er
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250 RPMs is really low. Is your A/C working fine? If it's not maybe the A/C compressor clutch is bad and your engine is having a hard time idling with that load. Any weird noises?
Pablo Quintana
98 SE Sport Contour
Honduras, Central America
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CEG\'er
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i didnt mean that it was idleing at 250 i meant that it was idleing about 250 lower than normal
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Hard-core CEG\'er
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Hard-core CEG\'er
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Originally posted by Mattyv12:
i didnt mean that it was idleing at 250 i meant that it was idleing about 250 lower than normal
Mine always idles 250 lower than normal, except when it idles 2000 higher than normal, or at times 500 higher than normal, and occasionally only 100 lower than normal, except on Tuesday, when it idles 350 higher than normal, unless the moon is full, when it........I'm convinced my car is demon possessed.....the blasted idleing does whatever it wants to do, whenever it wants to do it. I've come to accept anywhere between 500 and 2500 as normal. 
95 Contour Zetec, ATX (wrecked, sitting in the barn)
95 Mystique Zetec, MTX
2000 Taurus SEL 3.0L Duratec
1994 Crown Victoria LX 4.6 V8
1993 Chevy Silverado 4.3 V6
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Joined: May 2002
Posts: 21,653
I have no life
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I have no life
Joined: May 2002
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Originally posted by Mattyv12:
i didnt mean that it was idleing at 250 i meant that it was idleing about 250 lower than normal
Which would be anywhere from 250 to 450rpm depending on if your in park or in gear. Remove the a/c, it'll fix it. Though it makes the defroster take A LOT longer to work. ...
I've too accepted just about anything as a normal idle.
98.5 SVT
91 Escort GT (almost sold)
96 ATX Zetec (i brake to watch you swerve)
FS: SVT rear sway bar
WTB: Very cheap beater
CEG Dragon Run - October 13-15
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Joined: Jun 2003
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CEG\'er
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CEG\'er
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Originally posted by bentleywarren:
IIRC, the a/c comes on when the defroster is on. The a/c is probably putting the load on the engine.
The above statement is CORRECT!!!  The only additional electrical power drain is 1)the a/c clutch and 2)the blower!
Col. Bill Evans CAF (ret)
98 Contour GL Zetec ATX (totally stock)
Color-Willow Mist
104,XXX Miles
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Joined: Aug 2002
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CEG\'er
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CEG\'er
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Agreed, although when I warm up the Mystique with the windshield defroster fan on 3, the revs take quite a dip when I switch on the rear defroster as well.
It only takes a few seconds for the engine to recover as the computer adjusts the fuel to compensate.
- Jim
Our yardbirds:
Belvedere, our '96 Jeep Cherokee, 4.0L ATX, 85,000 and going strong
Spencer, our '03 Chrysler PT Crusier, 2.4L ATX, 28,000 and just getting started
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