Good morning. Title says it all - AC temperature difference between driver & passenger. In my 2012, even with dual AC deactivated and both sides set to the same temp (ex. 68 degrees F), a thermo pen shows about 4 degrees colder on the two passenger vents versus the two driver vents. The AC is still cold, mind, and it's otherwise working fine, just experiencing a discrepancy in coldness between driver and passenger sides. Any thoughts?

 

Not unusual. Contributing factors could include the shape and length of the HVAC air ducts on either side of the cabin, potential obstructions in the air ducts, proper operation of the blend doors, etc. If you have not installed a new cabin filter lately, you may try installing a new one and see if that makes any difference.

 

Thanks. Should add I just replaced the cabin filter two weeks ago. Certainly is not a big problem since both blow cool air, just an interesting observation.

 

Do you have as much airflow with the new filter?
I once installed a new charcoal cabin air filter that restricted air flow so much I tossed it after a week of my wife complaining the A/C didn't work anymore. A different non charcoal filter fixed it.

 

No issues with air flow or pressure/volume/quantity. (I went with a mid-range filter too).

 

The temperature of air coming out of the vent [for vehicles or even at home] is always cooler than the thermostat setting when the compressor [when cooling] is working]. Once the desired temperature is reached at thermostat the cooling stops.

The difference between the two sides is due to the fact the the cold air temperature drops as it sent through the ducts and the driver side vent is further from the evaporator/expansion valve. Also note that the in vehicles the air blower keeps running after the thermostat reaches set temp.

Salim

 

Suggest researching this a bit and watching some YT on it, but I had this issue on another Lexus once (but actually cool air on one side; uncooled air on the other so more exaggerated than your readings) and it was due to low refrigerant, which eventually we found a leak in the system.

Hope that yours is just how the system is designed; 4 degrees honestly is nothing but you'll want to research that it isn't the initial signs of something. We have a 2015 RX350 with no issues with AC, but I haven't measured the temp like you have.

Did something come up that made you want to measure it, or did you do it just for curiosity / informational purposes?

 

This makes sense.

 

In the high heat of the midwestern US summer, I noticed the passenger vents were slightly colder than the drivers vents. But again, both still pretty cool, just one side slightly colder than the other. Thanks.

 

Have you cleaned the interior temp sensor? You should find on the dash by the drivers right knee. I have different model than you, but it seems to be standard technology for this generation Lexus. The sensor gets full of lint and crud and what not and causes the climate control not to get a proper temp reading from side to side. See if you can find yours and clean it out, maybe you can narrow the difference

 

Good call - will check.