How does a blend door work?

already exists.

Would you like to merge this question into it?

already exists as an alternate of this question.

Would you like to make it the primary and merge this question into it?

exists and is an alternate of .

A blend door is short for Blend Air Door. There are other names such as temperature door, etc.. The blend door, blends or mixes the hot air with the cold air. There usually is an actuator motor that opens and closes the blend door a little at a time to adjust how much hot air and cold air to mix for the temperature setting you have chosen. If your blend door or doors are broken sometimes you will only get cold air coming thru the vents or maybe just hot air with no air conditioning. For more information on the fault codes, etc for the Jeep Grand Cherokee blend door problems, checkout the Blen Dor Store on Ebay. There is an easy blend door replacement kit with only two parts to install. No Dashboard Removal. The Blen Dor kit is guaranteed for as long as you own the vehicle. For more information try a search for Blen Dor .

Close, but not exactly. On most modern vehicles, air is constantly blown through the AC evaporator core and then the blend door can divert some or all of the air through the heater core. In full AC mode, the blend door is closed against the heater core inlet and all air flows around the heater core and directly into the vent system. In heater mode, the compressor is deactivated and the air flowing through the evaporator core has no temperature change. As before, the blend door will now direct some or all of the air flow through the heater core and into the vent system.

In the old days, the blend door was controlled by a slide lever on the AC panel which was connected to a cable that ran to the blend door. In the mid 90's most automotive companies went to computer control over the blend door, using a pseudo stepper motor to control the door. A common design flaw in these systems is the end point detection for door movement. For a computer algorithm to control the door, it has to "know" when the door is closed against the heater core or blocking the free flow of air through the vent system. This is done by driving the motor and door to a stall point and detecting a voltage surge from the motor as a digital signal indicating the end extent of movement. The catch is that over time the plastic doors cannot withstand the over-stress of the calibration routine and will break. When this happens, all control over heat and AC is lost.

The problem is common on multiple vehicles and HeaterTreater has built a line of products for the most severe cases. We are always looking for additional applications for our repair technology and would be happy to discuss how we can provide a solution for your particular issue.
9 people found this useful

Where is the blend door on a Ford Ranger?

The blend door sits vertically in the heater box behind the glove box. If you fully open the glove box, you can see the actuator motor on top of the heater box in the upper le

Where is the Blend door 2001 grand am?

in a body shop the blend door or panel is an adjacent part next to a new/repaired body of the vehicle. It is also painted to give a more uniform color to the vehicle with fres

What is a blend air door motor?

The blend door regulates heat and AC in today's automobiles. Generally the system is set up with air always flowing through the AC evaporator coils, and the compressor is eith

Explorer 2004 blend door?

Ford changed the plenum box in the Explorer in 2003 and the system is completely different from the previous models. However, the 03+ model years suffer from a similar blend d

Where is the Tahoe blend door actuator?

The blend door actuator on the late model Chevy Tahoe is located behind the dash in the glove box area. Broken blend doors and broken blend door actuators are a very common pr

What is a heater blend door?

it's the cable that connects your heating/cooling temp slide switch to the heater box inside the engine. If it's broken you will have no temp control.

Blend door actuator on my 1997 Sable works intermittantly?

That's exactly what my Windstar actuator did when it was failing - all depending on how cold it was: the colder the less likely it would work. I would suggest planning on rep

Where is the blend door in a Ford Explorer?

Remove glove box liner. Blend door is located in the heater/evaporator housing. There are several kits available to repair blend door shafts as well as troubleshoot system.

Where is the blend door on 96 explorer?

On a 1996 Ford Explorer : The blend door would be INSIDE the plastic case that has the heater core ( and air conditioning evaporator if equipped with A/C ) located below the

How do you tie the blend door with the shoestring?

If you take the dash apart enough to tie the blen door up you may as well just change the accuator which is probly whats wrong. but i would check the temp control knob first t

How do you test a blend door actuator?

There is no significant power at the three wire plug at the control knob, the three wires are directly wired to a potentiometer. In the five wire plug on the actuator there is