Fluctuating RPM at idle/park

[RRL]

Hey guys I have a 2021 heritage LC and just noticed today when I had my car parked and the engine running I could hear the engine kicking in every minute or so when I went inside the car I could see the RPMs fluctuating from around 700 up to 1000

It reminded me of when other vehicles I’ve had the air conditioning was on I could hear it kicking in

I shut off the heated seats and heated steering wheel and that seem to help for a little while and then I noticed it even with just the heat on
Which I typically leave it on the defrost foot combo

does anyone know if this is normal?

 

[bloc]

Try to see if the front of the AC compressor pulley (the clutch) rotates then stops rotating in common with the RPM fluctuations. It is the large diameter pulley near the bottom on the drivers side of the engine. Even with the AC “off” if your coolbox or defrost are running it can cycle the compressor. Though mine does a pretty good job of keeping the RPMs more steady than that.. maybe it’s a function of a new and not yet broken in engine vs mine being well used.

 

[2014TeeLC]

Try to see if the front of the AC compressor pulley (the clutch) rotates then stops rotating in common with the RPM fluctuations. It is the large diameter pulley near the bottom on the drivers side of the engine. Even with the AC “off” if your coolbox or defrost are running it can cycle the compressor. Though mine does a pretty good job of keeping the RPMs more steady than that.. maybe it’s a function of a new and not yet broken in engine vs mine being well used.

I have noticed the AC compressor will cycle occasionally while in "Auto" mode when heat is being demanded based on temp settings. It may be part of the overall humidity / air quality control from the HVAC system.

But 700-1,000 does seem to be a large variance unless the engine is cold. When my AC compressor cycles with a cold engine the RPM variance tends to be a little wider. With a warm engine the RPM variance is pretty minimal.

If your AC compressor is not cycling at all, then there may be something else going on. I'd put some miles on it and see if it resolves itself.