SpartanGuy

I have a 2003 ES 300. The AC works great but the heat only works on the passenger side. All vents blow air when the heat is on, but only the passenger side warms up. I thought it might be a door servo/actuator, but I would think if this is the problem both the driver and passenger sides would be blowing the same temperature air.(?)

Coolant: No issues. It's where it should be.
Temp Gage: No issues
Dual air: Both are set to fully hot

I'm a novice auto DIY person, but from what I've read it doesn't sound like a thermostat issue. Could it be the heater core or maybe a fuse?

Arsenii

Hello,

If you turn the system to Full Cold without engaging A/C, would the temperature from the Driver's vent change?

Here is a thread that describes entering the Diagnostics mode for the Climate Control with a lift of all the codes that can come up, see if there are any codes that would pop up, disregard Code 21 if you see it, it's a light sensor, and it can trigger the code in the dark environment.

It is definitely not a Temperature sensor, since when you put the car to Full Hot, it forces the ECU to open the hot air to full regardless of the sensor readings. If the coolant is properly filled, my guess would be that either the servo is bad, or the rod that drives it came off.

Hope this helps and best of luck!

SpartanGuy

Thanks, Arsenii. At full fan without AC engaged, all vents blow the same "neutral" air temp. I'll check the servo first to see if the arm came off or if it's bad. Is it near the firewall under the driver side dash?

Scott

Arsenii

Here is a Parts Catalogue for your car, it shows the location of each servo in the car. You need to be on the lookout for an 87106H No.1 servo, it is on the Driver's side, right besides the Mode Selector Servo, which can serve as a good reference, it is really hard to miss.

Hope this helps and best of luck!

SpartanGuy

Thanks, Arsenii! Very helpful.

SpartanGuy

Problem solved. Bear with me on the terminology here--just a home DIY guy. The white "servo arm" was stuck. When I raised and lowered the temperature, the arm wasn't moving to raise/lower the door lever. I loosened the screws on the servo, pulled it out about a half inch, and disengaged the arm pin from the door open/close lever. Then I raised and lowered the temperature again. The arm moved up and down this time so I knew the servo motor and gears were working. I put the servo arm pin back into the open/close lever and retightened the screws. With everything back in place, I raised and lowered the temperature again--now it works fine!!

Thanks to Arsenii, I knew where to find it!

Arsenii

Glad that fixed your issue!

Sounds like a relatively common issue on those, either the motor in the servo would get worn out or the mechanism would get gummed up, preventing the servo from moving. To make sure the issue won't return, it would make sense to pull the servo out completely, then take apart and clean it out, also inspecting the condition of the motor, here is a detailed thread on the subject.

Hope this helps and best of luck!

SpartanGuy

Thanks, Arsenii!