07 TSX passenger vents AC blow colder than driver side - Why?

[JeffKeryk]

I serivce a friends 2007 TSX with 140K. We picked up the car from a MBZ dealership about a year and a half ago.
He called and told me the passenger AC vents blow colder than the driver side vents. I didn't believe it. "Impossible", I said.
So he comes over and we take it for a spin. Sure enough, there is a noticeable difference.
The car does have a dual setting, but that was off.
The driver side feels like it needs a charge; the passenger side is fine.

I am planning on charging the system.
I would appreciate your thoughts.

 

[ctechbob]

Sounds like it would be some oddball blend door problem.

 

[The Critic]

Check the air mix motors.
But yes, inadequate refrigerant charge can sometimes cause this issue.

 

[mclasser]

Check the charge. The pass. side can blow colder when the charge is low since the evaporator is on that side.

 

[Chris142]

Low charge is most likely. Only flooding 1/2 of the evaporator

 

[gregk24]

Low charge. My 2006 Accord did this and it got worse quickly.

 

[cricket whisperer]

While the system design may be a bit different my Honda Odyssey had the same problem.
The cause turned out to be the expansion valve on the evaporator coil under the dashboard.
The tech found the charge OK, but the front left zone was colder that the right.

 

[mattd]

First thing to check is refrigerant charge. 9 times out of 10 on a Honda that is the problem.

 

[JeffKeryk]

Charged the AC system today after oil and ATF services.
Easy peasey; worked like a charm.

Thanks for all who posted; I appreciate your advise.