Air Comes Out of Defrost and Floor Vents Only

[Luther1288]

I have a 2008 dodge ram 1500. The knob for the vent mode is loose and by feel, I can tell it does not catch any of the modes. Air comes out of the defrost and floor vents only, with residual air coming out the dash vents.

Also the temperature doesn't switch over on command and works intermittently. Right now it's stuck on cold. It seems as if it turns on to the temperature I want when it feels like it (it could take months). This past summer, it turned over to a/c 2 days into a heat wave, and not it's stuck on a/c mode.

Any idea what the problem /problems could be?

 

[Martins hemi]

Probably your blend doors or blend door actuators
Mine broke a few years ago and had the same symptoms

 

[mpipes79]

Probably your blend doors or blend door actuators
Mine broke a few years ago and had the same symptoms

What did you do to fix?

 

[Oliver Closehauf]

Do a search on "blend door". Lots of posts. None you will be happy about.

 

[mpipes79]

can the blend door cause air to not come out at all?

 

[Oliver Closehauf]

You have more than one. There is a recirc door that lets outside air in or not, and there are the blend doors that change position to route the airflow. If those get messed up and in the wrong position they will just block air flow.

First thing to check though is to pull the fan and make sure the recirc door isn't sitting on top blocking flow.

 

[Martins hemi]

I had the whole suitcase rebuilt
New doors, ac and heater core

 

[GTyankee]

Not sure which unit you have
some units have a separate control body, ( Knobs & Buttons )

If you have an A/C & Radiator Shop nearby
They should have a fancy machine that plugs into the OBD2 Port & they can test all of the controls & tell you if the HVAC Doors are working or not

 

[mpipes79]

Do a search on "blend door". Lots of posts. None you will be happy about.

I've serched for other blend doors, but what is the chance they all went out at same time? I can't change air direction, I don't believe the recir door is working. AC blows cool air but not cold air unless parked in shade or evening/night time. Is there a fuse that works the blend doors, bought the truck used and it did not come with a book.

 

[Oliver Closehauf]

BLEND DOOR ACTUATOR
DESCRIPTION
The blend door actuators are reversible, 12-volt
Direct Current (DC), servo motors. Models with the
single zone heater and air conditioner system have a
single blend door, which is controlled by a single
blend door actuator. Models with the optional dual
zone front heater and air conditioner system have
dual blend doors, which are controlled by two blend
door actuators. The single zone blend door actuator is
located on the driver side end of the HVAC housing,
close to the dash panel. In the dual zone system, the
same blend door actuator used for the single zone
system becomes the driver side blend door actuator,
and is mechanically connected to only the driver side
blend door. In the dual zone system, a second separate
blend door actuator is also located on the top of
the HVAC housing and is mechanically connected to
only the passenger side blend door.
The blend door actuators are interchangeable with
each other, as well as with the actuators for the
mode door, defrost door and the recirculation door.
Each actuator is contained within an identical black
molded plastic housing with an integral wire connector
receptacle. Integral mounting tabs allow the
actuator to be secured with three screws to the
HVAC housing. Each actuator also has an identical
output shaft with splines that connects it to the linkage
that drives the proper door. The blend door
actuators do not require mechanical indexing to the
blend door linkage, as they are electronically calibrated
by the heater-A/C control module. The blend
door actuators cannot be adjusted or repaired and, if
damaged or faulty, they must be replaced.
OPERATION
Each blend door actuator is connected to the A/Cheater
control through the vehicle electrical system by a
dedicated two-wire lead and connector from the HVAC
wire harness. The blend door actuator can move the
blend-air door in two directions. When the A/C-heater
control pulls the voltage on one side of the motor connection
high and the other connection low, the blend-air
door will move in one direction. When the A/C-heater
control reverses the polarity of the voltage to the motor,
the blend-air door moves in the opposite direction.
When the A/C-heater control makes the voltage to both
connections high or both connections low, the blend-air
door stops and will not move. The motor connections
also provide a feedback signal to the A/C-heater control.
This feedback signal allows the A/C-heater control to
monitor the operation and relative positions of the blend
door actuator and the blend-air door. The A/C-heater
control learns the blend door stop positions during the
calibration procedure and will store a diagnostic trouble
code (DTC) for any problems it detects in the blend door
actuator circuits.
The blend door actuator can be diagnosed using a
DRBIIIt scan tool. Refer to Body Diagnostic Procedures
for more information. The blend door actuators
cannot be adjusted or repaired and, if damaged or
faulty, they must be replaced.

 

[Oliver Closehauf]

 

[Oliver Closehauf]

 

[Oliver Closehauf]

All of that is from the 05 service manual, not the 08, but I expect it's the same except for wire codes.
I see for the 05 there is a fuse that could possibly be related. Fuse 36. Several other convenience accessories run on that same fuse.

If you have any kind of a scan tool, see if you can pull any codes.

 

[Martins hemi]

Take the blower out and look up and see if the recic door is operating then look to the left and see if that door is operating

 

[GTyankee]

There is an error about the actuators
If an actuator is bad, you can work the controls & listen carefully for a Click, click, click
Usually that means that the drive gear inside of the actuator is missing a tooth. You can open the actuator & lift the gear off & rotate the gear, something like a 180 degrees & set it back in place.,
Before putting the actuator back in place, plug it in for test run.

Something else to think about, is the recirculation door when Open, Fresh Air is allowed to enter into the Cab.
It does not need to be Open to have A/C or Heat

By the way, The MOPAR Actuators are better, more reliable, than the Dorman Brand

.....................
Quoted from a post by Jawzs2

I'd try a quick calibration first, no guarantees, but for the price and 3 minutes of time, it can't hurt. Good luck

HVAC Manual Recalibration below

With the vehicle running set the HVAC blower to low

-Press and hold the recirculation button on the HVAC Control Head for 10 seconds and release.

-Now press and hold the recirculation button on the HVAC Control Head again until the recirculation LED begins to flash, then release.

-The system will perform a brief recalibration and reset faults

 

[GTyankee]

This is the firewall side of the HVAC unit
I think it may be the Dual zone type HVAC





This is a Newer year than yours, right at the beginning, you can hear an actuator clicking

DODGE RAM 1500-3500 BLEND DOOR ACTUATOR REPLACEMENT 2010-2012

This is for the door actuator https://www.amazon.ca/Dorman-604-005-Air-Door-Actuator/dp/B00CI6GGPM/ref=pd_ys_c_rfy_rp_m_289_1?_encoding=UTF8&pd_rd_i=B00CI6GG...

www.youtube.com

 

[mpipes79]

only way to repair is to remove the dash i guess
I'm not that mechanically experienced

 

[Oliver Closehauf]

This job is kind of involved. First thing is you have to go have your AC system evacuated. When you do that, you need to have them disconnect the lines to the evaporator and cap it all off or you will be replacing the dryer.

Then you have to psyche yourself up and schedule some downtime for your truck because you will need to drain the coolant from the heater core. I'd put a spring clamp on both heater hoses before disconnecting anything so you don't lose all of your coolant and make up a U shaped connector to sort of replace the heater core while you work.

There are youtube videos of the dash removal and then AC unit removal. It's not terribly hard as long as you have the tools and a helper. Just tedious.

You definitely want to put some old towels down on the floor when pulling the AC housing in case you drip coolant. You don't want to have to smell that for the rest of your life.

Of course before you do any of it you will want to get the replacement parts first.

Speaking of replacement parts, depending on the overall condition of your truck, maybe you should go to a self service junk yard and practice removing a replacement. You could fix it up, even install new heater core and evaporator and have it ready to swap in, then sell yours on craigslist to the next guy that needs to do the same.

Or, there are people that do this for a living. If you aren't mechanically inclined, start saving your money and shopping around for a place you can trust. Get some quotes.

People on this forum live to offer help. If you have a phone and can post pictures if you get in a jam you will get a lot of help if you decide to do it. Evacuating the AC correctly takes special tools though so you need to have it evac'd there first thing, and see if they will cut you a deal on the recharge.

 

[GTyankee]

20 years ago, i would have tackled pulling the whole HVAC unit,
but at 78 years old, i will just watch Youtube videos on trouble shooting.
Then i would find an old style Radiator & Air Conditioning shop, where that is all they will work on.
They would have a computerized tool that connects up to the OBD2 port & it can run the doors, by bypassing the Control knobs & buttons.

If it is discovered that you have Actuators that are bad, MOPAR cost about $40 each, Gen 4 Actuators are easily accessed, Gen 3 has one that is a B____, Mopar makes the very best Actuators

Chrysler doors break way to easily
Dorman doors are just a hair better

There is a company called Blend Door USA, their doors are light weight aluminum

...................................................................

very good video for you to watch as you enjoy a beverage of your choice

Dodge Ram Air Door repair Heater AC HeaterTreater

Video describing diagnostic process and repair for common Dodge RAM air door failures. Additional information is available at the HeaterTreater web site at ...

www.youtube.com

 

[mpipes79]

Ok....I have another question. Other vehicles I had, if you turn knob to defrost the ac shuts off....is that not the case for my dodge?