Rear AC Warm but Front AC Cold - 1998 5.4L XL 4WD

[green1998]

I have a 1998 XL 5.4L 4WD (original owner) with rear AC and the AC in the front vents is ice cold but the AC from the rear vents is now blowing warm. No combination of vent and temperature control knob changes will get cold air out the rear vents. Note - the air from the rear vents will get much hotter if the temperature knob is turned to hot so it appears to work for the hot setting.

Ideas for top issues and diagnosis?

 

[green1998]

Ideas? I suspect I should open up the rear AC area and see if the lines are cold and then inspect the mixer flap and perhaps limit it to the expansion valve? The rear unit vents have good airflow.

 

[JJinSFL]

Sounds similar to when I had a blend door actuator fail

 

[green1998]

I pulled the 3rd seat and removed the small access panel on the driver's rear side and located the 2 ac lines entering the panel area from under the vehicle - both were a room like temp with the rear ac unit in full cold selection. I then traced the 2 room temp lines to where they enter the small metal "block" and where they exit this small block: the top exit line was a room like temp but the bottom line was freezing cold and appears to lead to the AC coil area still covered with the greater panel. I am thinking the blend door actuator or vent has failed which will require me to remove the huge panel for complete access. Thoughts on my observation on the line observations?

 

[cecilbridge]

From your description and problem the rear AC blend door actuator seems to have failed . When you turn the the rear control knob from hot to cold, do U hear a noise like a flap flap flap or click click click at a certain setting ? Just remove the panel and check the blend door actuator - a little work jut worth it. Goodluck

 

[hwy73]

I think if you pop the cupholder out on the driver's side third row you may be able to get a look at that blend door actuator and possibly tell if it is functioning.