QuestionQUESTION: I have a 2001 dodge ram V6 magnum 3.9 L. when I have the cool air on are the air conditioner on cold it blows cool or cold for a short while. Then begins to blow hot air. I can hear a door closing which I guess is the blend door closing. Also on defrost, hot air only blows on the drivers side. Can this be repaired. I'm going to be replacing my heater core and because of the location of the blend door would this be a good time to repair the blend door. I believe the blend door is located just above the blower motor behind the glove box. Can you help me with locating it.
ANSWER: Hi Curtis,
The behavior you describe is likely related to the blend air door and its actuator. However the door and its actuator appear to be more centrally located than the blower motor as the air moves from right to left and reach the blend door for it to then be divided between the heater core and the evaporator core. The door shaft is vertical and the actuator is on the top of the unit and is electrical. The other door actuators are vacuum operated. The blend door lower end of its shaft is on the bottom of the box and you can probably feel it move if you touch it on the underside. The HVAC unit has to be removed from the cabin to actually remove the door or change the actuator. When changing out the actuator, set the temp control at mid-range (12 o'clock) before removal and then mate the upper end of the door with the actuator when re-assembling.
You do have to remove the HVAC box to also replace the heater core so that is the time to also replace/repair the issue of the blend door.
The door you describe at the right hand end near the glove box is probably the vacuum-operated recirculation door which is an optional choice when using the AC.
The present malfunction of the blend door could be related to an intermittent contact surface inside the temp control which is a variable resistor/voltage divider device which sends the actuator a variable voltage to change its rotational position and thus the mix. So it might not be an issue with the actuator. You could try spraying some electrical contact cleaner inside the control on the dash. Another possibility is that the mechanical connection between the door shaft and the actuator is compromised so the door may be free to move on its own.
Are you going to do the heater core exchange yourself? If so, it would be good to have the manual's pages, which are numerous. I could copy those if necessary and attach them to an email I would send to you directly, but I need to know your email address. But don't use the @ symbol, instead us "at" if you tell me it, or it will be automatically erased. It is a time-consuming effort to copy the pages so let me know in advance of your doing the job.
Roland
---------- FOLLOW-UP ----------
QUESTION: I'm going to do the heater core exchange myself. I use to let my mechanic do all my work, but now I do most of the work myself. An honest mechanic is hard to find. I believe my biggest problem will be keeping track of all the screws and bolts and where they go. I have another car to drive so I can take my time and do it right. If you could send me the manual's pages it would be greatly appreciated. I'll try the electrical contact cleaner first. My email address is 17thesaintatgmail.com Thank You So Much.
AnswerHi Curtis,
I will copy all those pages and send them to you, probably in several emails. I am tied up with guests until Sunday so you should start to get the pages on Monday. As to the heater core, if it is a slow leak you might try a dose of Bar's Leak in the system to see if it will seal up an obviate the need for removal of the HVAC housing.
Roland
