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Had front AC evaporator core replaced in October. In December when it got very cold I noticed that the heat was only (or mainly) blowing from the the dash vents whether the climate control was set to Auto (supposed to default to the floor) or manually directed to the floor. Never noticed this issue in any previous winters or prior to the recent evaporator core replacement. Assume the cause is that one or more servo motor/dampers have failed. Question for those of you that have replaced evaporator cores. How likely is it that the damper/servo motor failure(s) was caused by the mechanic incorrectly putting everything back together 2 months ago? Assuming to fix the servo motors would need to take out the whole dash again?
Oh boy.....I replaced my evaporator a few months ago and it's a major undertaking. The enclosure that holds the evap and heater core is a complex design. There are 3 (iirc) servo motors attached to the enclosure that actuate the mixing flaps/ doors. You can see the actuators and check to see if they are moving properly from the floor. There is 1 on the drivers side and 2 on the passenger side. You'll have to remove the lower dash panels, drop down the glove box door and remove the air filter. That's all very easy, though.
Once you get to where you can see the actuators, (they're smaller black motors about the size of a pack of cigarettes), you can start going through the HVAC functions to see if they are moving properly. They use small cams to move the flaps. Hopefully, nothing is broken and they are moving freely.
If one or more are broken, or off track, then you (or the mechanic) will have to start removing dash/ console panels until you can access the motors and mounting screws.
Hopefully your mechanic can fix it under warranty, if they are the ones that made the mistake when doing the repair.
thanks for the response. given the amount of labor (6-7 hours) to replace the servo motors the shop isn't willing to take responsibility for having caused the problem ("things like this fail on 10 year old cars"). seems pretty coincidental to me. frustrating to say the least. I could see paying for whatever servo motors are required and having them cover the labor but that doesn't seem to be an offer. any thoughts as to proving they vs. my old car are to blame?
If you change the temperature (once the engine is warmed up) from hot to cold and back again, if you can feel the temperature change then the blend motor is doing it's job.
If you manually change the air direction (using the touch-screen or the switches if you don't have the nav option), does the airflow change? So if you tell it to go out the defrost vents (base of the windshield) then the floor vents, you can feel the air blow from each?
If that happens then the duct motors are doing their job. If one side does and the other does not, then then the motor for that side is broken (the dual-zone system).
If after that, if the air direction doesn't suit your expectations when in Auto mode, you may be out of luck as that's how Lexus programmed the system.
An example of this is how it won't blow air on you in winter until the coolant is up to temp (so you don't get an icy blast). It's a design choice made by Lexus.
any thoughts as to proving they vs. my old car are to blame?
If you crawl down there and go through the controls, you should see the servos moving the cams and levers, if they are both connected with trier electrical plugs and they are physically in the right spots, with no screws loose, disconnected from the levers, etc.
It could be something as simple as one or more of them weren't plugged back in. Or, it could be they were reinstalled improperly, (it's tricky to put that entire heater box enclosure back together) and off track/ broken, etc. Hopefully that's not it.
thanks for the ideas guys. will see what I can hear and see under there. did get the shop that did the evaporator to agree to cover the labor to figure it out and fix it.
I did as you suggested and took off the bottom dash panels and removed glove box door and cabin filter. can't see anything unplugged or anything happening when I switch from dash heat to floor heat on the climate control. when I switch to floor heat a little bit of heat comes from the floor vents but the preponderance comes from the dash vents. guess I could live with it and just almost close the two center dash vents in the winter but will probably go back to the shop I used for the evaporator to investigate since they have agreed to cover the labor on dash removal. just seems like they must have not put things back together correctly rather than all the servo motors coincidentally failing.
If you cant see the servo motors themselves moving the small cams and arms, then they might just be unplugged. They each have a little plug that powers them, but finding them can be a pain if they got shoved up inside the dash somewhere. Can you see if the plugs are connected on each of them?
Does your gx have the ML Navigation system?
thanks again. will take another look. only saw one plug and it seemed to be plugged in. as you say, tough to see much up in there even with the bottom panel and glove box removed. my GX does have the Nav system.
Took the car back to the shop that replaced the front evaporator core in October. When they took the dash apart they found that there was a broken plastic retainer clip on the blend door. They replaced the retainer clip on the blend door and reset the actuators and everything works fine. No charge!
There should be a slotted arm that connects the servo to the shaft for the blend door. Based on your other photos, it looks like it has either snapped off or been removed for some reason (honestly - no idea why anyone would do that)
There should be a slotted arm that connects the servo to the shaft for the blend door. Based on your other photos, it looks like it has either snapped off or been removed for some reason (honestly - no idea why anyone would do that)
Chip H.
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previous owner mentioned that he had issues with heater core and he said that it was replaced. I am trying to find his contact so I can reach out and ask what have they done!
Do you know the part number for the missing piece? Or it's the part of the whole air box? Or if I could manually switch it?
You might could use some pliers to move the shaft into a position that gets the air directed how you like. But of course, changing it afterwards would be a huge pain.
You might also look for one in a wrecked GX to see what the price would be.
01-17-17, 02:36 PM
Servo motors/evaporator core replacement (2006 GX470)
