I have a V4 2005 Accord LX. The passenger side heater side works fine, while the drivers side doesn't get as hot as the passengers side,and when the car is idling, the driver side heater gets cold. Once I start driving it again, it gets warmer but not as hot as the passenger side. Do you guys have any idea what might be wrong?

 

I really should know or like research the problem before I reply here but I will write that your problem is likely in the HVAC box/unit. There are various doors or flaps that are used to direct and redirect airflow, they are controlled by electric motors. Fixing the problem would entail removing the lower dash pieces and glovebox to access the box. THOUGH you may just have some sort of block in your vent .Try blocking the other vents and quickly turning the fan on, maybe also try covering and uncovering the drivers vent, ya know the one thats having flow problems

 

Be sure to check the coolant level. Also do both sides cool even with the ac on?

There is a "self test" that can be run on the HVAC unit to check for issues. Does yours have the single or dual temp settings - can the dirvers and pass side be set to different temps?

 

AC works fine on both side. It's got single temp setting. The check engine light has been on for a while and a lot of places couldn't find the code.
I took it to dealership and they told me it's a faulty water temperature gauge sensor.

 

Honda had service bulletins for other models similar to this.

The symptom of the heat from the driver’s side-vent being lower than the heat from the front passenger’s-side vent can be due to the heater core being partially clogged; decreasing the heater performance on the driver’s side.

Flushing the heater core is normally tried as the corrective action.

 

This is surprising as all the vents on the car get the heat from the same heater core and not only that but any and all of the vents get hot air from any and all portions of the core. The cooling system doesn't usually become contaminated by debris either but its of course possible.

 

"Accordian47" -Hard to explain in "text" - but low cooling and low heat can be because of the temps coming off the evap or heater core at different places.

So just for giggles play along with this.....if the top of the heater core is getting hot - not the bottom - and pass side "gets" the most air flow from the top of the heater core

It is also well known that a low ac charge will cause uneven cooling from side to side for the same reason.....one side/half/part of the evap will get cold and if most of the air flowing across that part of the evap is going more towards one side of the car....well that side will get colder than the other.

So please read/mess with these things long enough......these "strange things" will actually make sense and we are not "off our rocker" when we ask about/suggest that this IS POSSIBLE.

PS.....remember that many of the settings for heat will still cause the ac to function so the hvac can try to get the air temp to the temp you have it set at. So please be sure that when you are "asking" for heat from the car, the ac compressor is not on - can't remember which gens allowed you to turn off the ac compressor.