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Dodge Ram Climate Control

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  • dokkiedokkie Posts: 8
    is it possible that the switch on the dash for temp control may be gone?? I have tested with a wire tester and i have power but only to 1 of the 3 wires that conect the switch and the blend door motor is this normal? i don't think the door is broke because i can set the temp with a pair of pliers from cold to warm to hot by turning the shaft that comes out towards the floor (with motor taken off). Also too like a good student i have tried everything u have suggested which includes unhooking the battery so any further advice will be followed and greatly appreciated.
  • Dodge chose to implement a different control scheme for the HVAC system than other Chrysler products and Ford and Chevrolet, so I'll address all the different issues in general so that you can see the commonalities between the fails.

    Most systems use a "digital" control for vent selection and re-circ. By digital, I mean 1/0, open/closed, and this type of control is easily done with vacuum control. The vacuum switch is either on or off, and the door open or closed. This is fine for all the control functions other than the blend door. No one want the fine control of being able to put 90% of the air through the defrost and 10 through the floor and then decide to change it to 73% through the defrost and 27% through the floor, so it's either on or off with no fine control. The blend door is different because you want the control to be able to change the temperature from 73 degrees to 72 degrees and this is accomplished by moving the door slightly to change the mix of air going through the heater core.

    Vacuum control is problematic because you have to connect to the engine intake system, run little tubes to the various functions, use mechanical vacuum switches...and hope it doesn't develop leaks over time. Dodge avoided the vacuum "problems" by using electronic servo motor control for all the HVAC functions. The scheme connects a small DC motor to each of the door axles with control from the central computer. Each motor has two wires(not three) and the computer controls the direction of movement by reversing the voltage polarity on these two lines. The problem is that the computer has to know the point when the door is fully closed or fully open. It finds this point by driving the door to the extent of movement and recording a voltage signal from a stalled motor. Think of it like rolling up a hand cranked window. How do you know when the window is fully up or down. Easy, you can watch the window and stop just in time or turn til you feel resistance to movement and stop. Most of us have better sense than to torque the handle hard after it stops moving, but the computer system in the RAM does not have the same sense. It torques the door HARD every time it checks for the extents of movement and will eventually break the axle connector or the cheap plastic doors used on the RAM. This is the root cause of all the failures on the different control doors. The RAM is worse than the other automobiles we look at because of the decision to use servo motor control for all functions where most trucks use the motors for blend doors only. Once you break a door, the approved Dodge repair process is to disassemble the dash, disconnect the coolant and refrigerant lines, and remove the plenum box. It's fairly simple to open the box and replace the plastic doors with new plastic doors that will also fail over time. The doors are cheap, but the labor to disassemble the truck to get to the door will run in the $1k range. There are aftermarket solutions that avoid the high dollar work.

    So, let's follow the air through the system and look at the different doors that control the flow.
    1. Air enters the system through either an external vent or internal vent(re-circ). This is an either/or choice. If both the external and internal vents are open, air just flows into the external intake and out of the internal intake at highway speeds...like having a window rolled down all the time. The re-circ door is easy to see if you are having these kinds of symptoms by fully opening the glove box and looking to the upper right. With re-circ off, the door should be pressed against the inside of the grate covering the internal intake port and it should move when you turn re-circ on. If it isn't moving, it is broken and needs to be replaced.

    2. The air taken in in #1 now flows through the evaporator core. If the compressor is running, the air is cooled, if off the effect is neutral. The air is either cooled or ambient depending on the electronic signals to the clutch on the compressor. Air now hits the blend doors which can divert some or all of this air through the heater core. For max AC, you want the compressor on and no air through the heater core and for max heat you want the compressor off and all air diverted through the heater core. The system can change the on/off cycle of the compressor and position of the blend door to regulate temperature between max heat and max AC. This is the only component in the system that regulates the temperature of the air flow. If you are seeing problems with temperature control, the leading suspect is a broken blend door. Dodge also threw another curve into this by designing separate ducts for passenger and driver with some added complexity and two motors for the dual control systems. The plenum box is the same with either dual or single control and a differential between passenger and driver temperatures is a strong indication of blend door breakage.

    3. The conditioned air from the blend door now flows through the Mode 1 door. This door selects between dash vent and defrost/floor. If you have air flow through the dash vents all the time or no flow through the vents all the time, the Mode 1 door is broken. The door can physically break off and lodge in strange positions so it may not be completely black and white, but inability to control the dash vents is a broken Mode 1 door.

    4. The Mode 1 door will either push air out of the vents or allow the air flow to go to the Mode 2 door. This door chooses between the defrost vent and the floor vents. The system is designed to be a little "leaky", so choosing defrost will put most of the flow onto the windshield with a little leakage to the floor and the opposite situation when the door chooses to allow air to the floor. An inability to regulate between defrost and floor is an indication of a broken Mode 2 door.

    All four systems are equally susceptible to failure. Since the computer system is capable of detecting the movement extents of all four systems, it is also capable of throwing codes for a failure of any of the doors. The above describes the symptomatic analysis of the system, but the codes will also show any problems. The best diagnosis is to see a symptom that matches a code. You have to have the special Chrysler computer diagnostic system to read the codes. You may be able to find a shop that will do this for little cost, or maybe borrow a reader from one of the big parts chains. Note that the doors will "bend" before they break and the variation in calibration can throw codes even though the doors are not yet broken. The door may operate OK even with a code, but once you see a code, it's only a matter of time until it breaks.

    I know, I know, waaaaay too much information and complexity. Blame Dodge, not me. Unfortunately, theres more if you go looking for it. The system can be reliably repaired without extensive work and cost.
  • resqtechresqtech Posts: 1
    After reading alot of the reviews I apologize for repeating anything but each of the blower problems seem like they all have a different twist and I called to see how much the controller was for my truck and the dealer gave me a price of $153 that I would hate to spend if not needed. The problem I have with my '05 1500 is that the blower is stuck on the floor with just very little air coming out of the defrost when I choose 3 or 4 on the speed controller. I have no problem with the speed control, I can select any of the speeds. I also have no problem with the temperature control in the heater or the a/c mode, I can choose any selection for temperature. My truck is not dual temperature control and the air flow and temp seems to be the same on the drivers side floor as it is on the passenger side. Something that I did notice about a week before the blower got stuck on the floor was that one time when I started the truck with the controls set where they were when I turned the truck off, the indicator lights on the a/c button and the heated mirrors button flashed 4 times and then went out, those buttons also still work. It just won't blow anywhere other than the floor. Do you think is a controller problem or is it the mode or defroster door(s)? Any help would be greatly appreciated.
  • The actuator motors are simple DC motors geared to turn the door slowly. It's actually rare for the motor to go bad. The more common issue is for the blend door axle to strip or break and the motor will lose it's calibration limits and be shut down by the computer. The motor is good, but the computer can't find a stop point and sends it into hibernation mode.

    Your symptoms are indicative of a Mode door failure and the system can be repaired for less than the dealer wants for a new motor that won't solve the problem anyway. You can search the internet for more information on diagnosing and solving the problem.
  • sk4910sk4910 Posts: 2
    I have a 2006 Dodge Ram 1500 SLT quad cab with a 4.7L engine. Recently my air conditioner gets hot when the trick is idling. Its like the heater kicks on, the air gets hotter than whats outside and very humid to the point of fogging up my windows. The a/c works fine while the truck is moving. The freon level is good, and I changed the radiator fan clutch. There is also a pop sound that comes from the passenger side dash every time I start the truck. The passenger side a/c runs 80 degrees F while the driver side runs 20 degrees cooler. My truck is out of warranty so I was hoping someone has experience this same issue and could point me in the right direction.
  • The popping sound is a clue that there might be problems with the air flow doors in your truck. It appears that you are getting good AC compressor operation and coolant flow, so "hot" and "cold" is getting into the passenger compartment. It sounds like the problem is how the temperature is being regulated by the air flow circuits.

    The RAM has four different electronically controlled doors in the system and most likely your problem will be traced to one or more of these systems failing. The four actuator motors are connected directly to the plastic control doors and it is a common failure for the plastic to break and lose control over the door. Once this happens, the computer system detects a fault in the system and you can get all kinds of strange behavior. Once a failure is detected, the computer shuts down the suspect actuator motor and goes into a state of confusion. The motors themselves are actually fairly robust, but the plastic doors are weak and break.

    Here are the four systems you need to check:
    1. Re-circ door - regulates between internal and external air into the plenum box.
    2. Blend door - diverts some or all of the air flow through the heater core to regulate temperature.
    3. Mode 1 door - controls air flow to dash vents or defrost/floor.
    4. Mode 2 door - when mode 1 diverts the air away from the dash vents, this regulates between 90% defrost and 90% floor.

    The diagnosis is fairly simple. You can read the codes with a special Chrysler computer diagnostic tool. You may be able to get one of the big parts stores to do this for free if they believe that they can sell you something, or go by the dealer and pay for a diagnostic report. The other way is to analyze the symptoms and examine the plenum box. You can easily figure out the problems once the center console and glove box have been pulled. Figure a couple of hours work.

    There are aftermarket solutions for the weak doors and full diagnostic procedures to trace and resolve the problems. The work is well within the skills of most shade tree mechanics and significantly cheaper than the dealer fix.
  • bndckrbndckr Posts: 1
    kcram: I have a 04 dodge 2500 with climate control with somewhat the same problem.

    At first I had a fan problem and had to bang on it to jump start it... finally bought a new fan and replaced it. Still works good.

    Then the A/C would work on driver's side and heat on passenger side. Driving across country in the middle of the summer it was a pain. Finally stopped in Lawrence, KS(?) and the tech told me that he it was the valve system and he worked them until they worked ok. They did and no charge.

    It's Apr 09 and it started doing it again. I would tear into it and do it myself, but I don't have a clue as to where these "valves" are or how to get into them.

    I live in San Diego and the closest dealer to me is in Escondido and really hate to take it there as they ALWAYS try to do the most expensive thing that there is... Which would be the truck computer... no way jose.

    Would appreciate it if some one could give me an idea where these valves are and any little secrets of how to get to them.
  • stanoskistanoski Posts: 76
    Anyone else having this problem?? I have an 2007 RAM 1500 that smells like an old musty towel for about 1 to 2 minutes when the AC is first turned on and then goes away. Same issue since new and in either fresh air or recirulating position. Also does it for 1 to 2 minutes when you turn off the AC and just let the fan run.

    Never had this in my Ford :(

    Anyone can help? Thanks

    Ski in TX
  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,496
    You likely have mold from moisture in the system. Turn the AC on recirc and fog your interior with Lysol spray until the system has sucked it all in. Let it run that way for a few minutes... that should kill the mold, but if it was a heavy growth, you may need to do that few times.

    kcram - Pickups/Wagons Host

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • You also need to check that the drain hose coming out of the plenum box and dripping out behind the right front wheel is clear. If the hose is stopped up or not flowing efficiently, it can cause moisture build-up and promote growth of mildew.

    The internal intake port is located behind the glove box in the upper right corner. With the fan running and the system on re-circ, any liquid sprayed into the intake will be pulled through the evaporator core. Don't worry about too much liquid as it will be blocked by the core and drain out the bottom through the hose mentioned above.

    HeaterTreater
  • Watch for a video showing the entire analysis and repair process to show up on youtube. Should be posted on Friday 4/24/09. The dash has a lot of plastic and screws, but it doesn't take a lot of skill to pull the glove box and center control panel to gain access to the plenum box. It will take an hour or so to fully analyze any failures, but it's just time pulling screws and pulling off panels. Once you see the tricks, it's actually very simple.

    HeaterTreater
  • sk4910sk4910 Posts: 2
    The truck getting hot during idling was a bad condensor fan motor. I replaced it and that problem went away. I have checked the re-circ door and the blend door through the glove compartment hole and both of those seem to be operating properly. The popping sound has gone away so I'm guessing the system has shut down that motor. How is it possible that a single zone system can get two different temps. The dual zone system I am told has two blemd doors to separate the two zones and the single zone system has one. When I select the different flow options, i.e. floor, defrost, face, the system seems to be switching properly, but maintains the two very distinct temps. Does the single zone system have two blend doors, where the second one could be my problem?
  • Yes, the dual control has two doors and two motors. The single control is one blend door, but it's really just the same two doors connected together in the middle. Think of it like two flags on a flag pole. The connection between the two doors is very weak and it's possible for one "flag" to break off. The symptom is OK operation on the driver's side, and failure on the passenger side. The Ram has a unique blend scheme with a door above and below the heater core. The top and bottom doors move in unison to sort of "clam shell" the heater core.

    On the single control both the top and bottom set of doors have the same problem with a weak connection between the doors and if you have a broken one on either pair, you'll get strange HVAC behavior. There are aftermarket solutions for this problem, and additional pictures and video that can be found on the internet.

    HeaterTreater
  • diershwdiershw Posts: 1
    2001 ram pickup 2500 10 cylinder. I get no heat by turning up the thermostat until the exact half way point. One click past half way and I get full heat. Turning the thermostat back one click turns off the heat again. The dash control panel was replaced with no change in the performance. Help please
    Harry
  • Here's what I think is happening. The motor connector has a strange interface to the plastic blend door that has a tendency to slip. The forces of the actuator motor on the door are too strong and will over time either strip the motor connection or break the plastic axle receptor. When you get the slip type failure, the motor will turn to a certain point, and skip, allowing the door to fall back. Think of it like a record skipping.

    I think you are seeing the door move to a closed point, then slipping and falling back. It will only get worse. In order to diagnose the problem, you will have to get to the plenum box and remove the actuator motor and examine the axle connector. There is a video on YouTube that will give you a step by step process to get to the box, along with information on how to diagnose problems, and a repair procedure that might be of interest. Search "Dodge Ram Heater" to find the video.

    HeaterTreater
  • budc130budc130 Posts: 1
    What is the name of the video thats showing on youtube about this repair on air conditioner system?
  • You can find the video by searching "Dodge Ram Heater" or my username or youtube. There are several parts, so you may have to look a little to get them in the proper sequence.
  • wes01wes01 Posts: 2
    I have a 01 2500 5.9 cummins. when in turn my AC on the passenger floor board gets soaked with water. Anyone know where it is coming from and how to stop it?
  • partsman2kpartsman2k Posts: 15
    Your drain tube it stopped up. If you get under your truck behind your right front wheel and look up you should see a plastic tube sticking down. take a water hose with a nozzle on it and spray it up into the tube to clean it out and you should be fine
  • davidlvgdavidlvg Posts: 3
    Sounds to me like you need to replace your heater core.
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