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Colder AC after changes

This past weekend I went in and had my 2003 Impala’s radiator fluid drained and refilled, the cabin filter replaced and the engine filter replaced. Since we got to over 80 on Saturday after I picked up the car I actually went and used the AC and for the life of me it now seems to a lot cooler inside the car. My question is could having those things done really made the AC work better and cool the car more or am I just dreaming?

Yup. But it’s a good dream. Enjoy it.

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You’d be surprised how much better the A/C will work when the cabin air filter isn’t completely plugged up.


A dirty cabin can restrict airflow through the hvac system.

IF the cabin air filter filter on MAX yes increase air flow would make it seem cooler. I can not get a difinative answer on my car, but it seems it only filters outside air flowing into the cabin.

How did you reach this conclusion?

If it filters outside air, then that’s the normal air flow situation. “max” settings recirculate air. So a plugged cabin air filter is the only change that might explain improved a/c.

Two possibilities –

Confirmation bias (not a bad thing here; if you think it feels colder, then just enjoy it).

80 degrees is not all that hot. Maybe the A/C wouldn’t feel so cold if outside temp were 95.


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Not a conclusion, more a guess. When I finally changed mine it was loaded with leaves, pollen and dirt. Noticed increased airflow outside air setting , no change on recirculating (max) setting. Can not find an answer to this. 06 Mustang, if you have a source please share. I have looked, no success.

Like I said, recirc doesn’t go through the filter, ‘outside air’ setting does.

My Insight filters all air going to the blower, but I don’t know what GM does.


Given their description (no change on recirc, big change on outside air, lots of outside junk on the filter) I’m pretty sure my description’s right.



I promise a 100% refund if I’m wrong!

No need…you’re right (as usual). I just didn’t think GM was THAT cheap:



I wonder if, after the work on the Impala was completed, your area went through a period of higher atmospheric pressure and low humidity. Part of the effect of air conditioning is to remove the humidity in the air. If the atmosphere already has reduced humidity, the air discharged from your air conditioning unit is even dryer. This dryer air absorbs even more moisture from your skin and makes it seem as though the discharge from the air conditioning is even colder. My guess is that if you measured the discharge from the AC with a thermometer under high pressure and low humidity and low atmospheric pressure and high humidity under the same outdoor temperature the readings on the thermometer would be the same.

There is a chance that the clean cabin filter is making a difference, but I think the more likely cause is the placebo effect.

My car always seems to run just a bit smoother after an oil change. I fully attribute it to the placebo effect.

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There’s no question IMHO that the placebo effect is real, and likely a factor here. I feel the placebo effect after every task, auto related or not!

However, my original post that the new filter wouldn’t affect the AC was, admittedly, written without sufficient thought. Replacing a dirty/clogged cabin filter can’t make the ACV system more efficient… but it CAN make the AC system more EFFECTIVE! Chilled/dried air cannot cool the cabin if it can’t get to the cabin.