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2003 SLS
Joined
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33 Posts
Discussion Starter · #1 ·
Thought I should start a new thread for an old issue.
When I'm driving it doesn't matter accelerating, decelerating, cruise control on or off. My RPM will drop and if at night I can see my headlights dim. I'm sure they do it during the day just can't tell. It only lasts a split second and then recovers.
Any ideas?
 

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Super Moderator
2010 DTS
Joined
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88,781 Posts
How big of an RPM drop are we talking about?

My '03 DHS used to do the momentary headlamp dim thing within the first 5 minutes after startup for the 16 years I owned it. Never was a problem, but I never noticed an RPM drop associated with it.
 

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Administrator
2002 F55 STS, 2014 Explorer XLT, F-150s
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75,860 Posts
If this slight rpm hiccup is cyclical it may be the A/C clutch engaging/disengaging due to a slightly low refrigerant charge.

Turn OFF the entire HVAC system and see if the phenomenon still occurs. Many owners run around with the system in AUTO 24/7/365 and never give it a thought.
 

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2003 SLS
Joined
·
33 Posts
Discussion Starter · #4 ·
If this slight rpm hiccup is cyclical it may be the A/C clutch engaging/disengaging due to a slightly low refrigerant charge.

Turn OFF the entire HVAC system and see if the phenomenon still occurs. Many owners run around with the system in AUTO 24/7/365 and never give it a thought.
I'm pretty sure it happens in the winter too. But I will make a point to check it out. Thanks.
 

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Administrator
2002 F55 STS, 2014 Explorer XLT, F-150s
Joined
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75,860 Posts
The A/C compressor also runs when you set DEFROST - in winter.
 
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