[Sues-SLS]

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?

 

[Ranger]

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.

 

[Submariner409]

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.

 

[Sues-SLS]

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.

 

[Submariner409]

The A/C compressor also runs when you set DEFROST - in winter.