DreamRDX

Just purchased a used 07 RDX and the engine fans kick on often, but only for a few seconds at a time. It's about 50 degree's where I live right now, so I find this odd. Is this normal?

BleuM&M

Yep, mine does the same thing even when I start cold and it's in the upper 40s. Most Honda products seem to do similar but to a lesser extent.

DreamRDX

That makes me feel alittle better. I figured it was due to the turbo charged motor and no kind of venting in the hood. Im sure the underhood temps are HOT.

Boon

If you're talking about the fan noises from the exterior, then it's the RDX's intercooler. Turning off your A/C (it's switched on if you're in "auto" mode...regardless of temperature) will cut it out completely.

number84

+1

i'm still trying to figure out why the compressor turns on when you have it in "auto" even if you are pumping heat out.

i now am in the habit of pushing "auto" first (so the fan speeds and locations are auto) and then manually turning off the a/c. 2 step process but so far it seems my mileage is a little better now. still want to compare after a few more tanks though.

MMike1981

in one of the service bulletins for the RDX...this issue was talked about. http://www.in.honda.com/Rjanisis/pubs/SN/B061000.PDF (middle of page 1)

its 100% normal. The fan in the RDX is dbl the size of the TL. The turbo requires more power and heavier cycling. relax people

number84

so, the question remains. when in 'auto', does it mean the compressor is always on? if yes, that seems like a waste of gas. the fan and compressor do seem to be tied together, since when we hit 'a/c off', the fan immediately turns off no matter if heat/cold is being pumped out.

sasair

Yes, when in full auto, the climate control always has the AC on. Heat or cooling doesn't matter, they want dry dehumidified air to pump into the cabin whether its hot or cold. AC doesn't have to be cold. In the winter they want dry air so your windows don't fog up.

That said if they really wanted to make it full auto, they should put a humidity sensor in the vehicle that would turn the AC on or off automatically. I'm already in the habit of hitting the auto button then the AC button to keep the AC off if I don't need it.

Boon

Ahh, so that's why. This is a trait in all the cars I've driven when climate control is set on "auto" (BMW X3, Ford Freestyle). The A/C would engage no matter what the temp was...but it was one of those things I never really noticed since the fans weren't as loud.

Not a huge deal, but I pretty much do what Sasair does so the RDX runs quieter.

DreamRDX

Great info guys, thanks for the help!