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HVAC Will Not Blow on Defrost/Windshield

82K views 65 replies 25 participants last post by  Rco 
#1 ·
Hello,
Nice place you guys got here.

I have an 07 Limited v6 154k with the dual automatic climate control and the HVAC will not direct the air to the defrost/windshield position. All the other HVAC controls seem to be working but the defrost mode. When I press the defrost button the air is directed to the front vents, primarily the vests furthest to the sides (round ones, not the small window vents on top).

I looked through here and found some handy repair manual pdf pages that took me to the HVAC check mode procedure. I ran the indicator, actuator, and sensor checks and got nothing back for codes. During the actuator check there was no air blowing out of the defrost vent during any of the 8ish positions it runs through.The was one noticeable click sound at the end of the actuator check cycle (when it returns to position 1) but no repetitive clicking and the sound didn't seem out of the ordinary to me.

I'm not sure where to go next. I guess I could try to pull out the actuators and inspect them but I'm not sure which one to start with and if I can even get to them.

Thanks in advance for you help.
 
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#2 ·
Got any kids? I've heard of Lego blocks, pens, even action figures being dropped down the vents. It doesn't take much to keep a vent door from actuating.
 
#3 ·
No kids and get's kept pretty clean. If there was something down in there would it set off a code on the actuator check? How would I go about getting to the vent door to clear it? is the actuator in question located on the driver or passenger side?
 
#6 · (Edited)
So, here is the update.
1) I took out the glove box and peeked inside the cabin air filter and didn't see anything of note.
2) I have observed both accessible actuator motors (Temperature control and Vent control) and both seem to be moving predictably and smoothly. I did not remove them at this time as I'm not sure how or if this would be of any help.

That leaves me with the guess that one of the baffles/louvers/dampers has broken off the little plastic cam that controls it. This would leave the motors to spin their merry hearts out without setting off a code. but yet the symptom persists.

I am now faced with a repair that will involve the dash coming off.

I am also considering buying an inspection camera to get a better look at the problem but I still do not have a good enough understanding of how the internals of the beast operate to give me a clear answer as to what I'm looking at.
 
#7 ·
There are actually 4 servomotors: Driver's air mix, passenger air mix, air inlet, and air vent (mode).

This PDF file may give you some insight as to how the system works:

AC Description
 
#9 ·
Can't answer your specific question but is it possible to disconnect the linkage to see if the damper is stuck or the servo isn't working?
Also I don't implicitly trust electronic monitors to generate codes for every possible defect.
 
#10 ·
It is the automatic servo control, it does not have linkage as far as I know of.

Dug further into it today but didnt really find anything. Headed to the dealer thursday for a diagnosis. I dared to ask how much the new assembly would be if there was a broken damper part... $2100. Its all one part, housing, servos, heater core, and evap core. I only pray that it is the $350 ecu or ac amp. Please anything besides a mechanical problem.
 
#12 ·
I imagine that I'm a sort of Luddite but with that sort of problem I'm pleased that I have the manual climate control system! JuneBug's suggestion for buying an extended service plan by owners with the automatic system certainly is convincing!
 
#13 ·
I drive 70k a year in for work in this beast. I have taken it up and down mountain trails that scare equipped off-road jeeps. I have a dented oil pan, completely ripped off plastic splashguard, banged the trailer hitch on things soo many times, I have abused the ever loving hell out of this car/truck thing. NOTHING has failed me until this defroster. Not. One. Damn. Part.

I will pull apart the dash myself and get you pictures of the guts if need be. This rig has taken me literally to the top of mountains (I work on cell tower equipment). I have gotten it stuck and unstuck, stuck again, unstuck, then pulled out the buddy's 1 ton from the mud. Nobody disrespects the power of this little monster on my work sites.

Be proud of your car/truck/rocket. They are a formidable beast.

... but dammit, why did the defroster have to go out the week before the first snow.
 
#18 ·
I wish I had better news for you...
There is one motor up at the top of the passenger side air box. It controls all of the vent positions by actuating 2 internal baffles that are connected to the main gear by peg slots and 2 actuating 1/6th gears. In my case something had fallen down the defrost vent, jammed the upper baffle (controls front and defrost vents), and the servo motor snapped the cam of the upper baffle clean off.

No, the cam is not fixable, and no, you probably shouldn't attempt to.

Here is what I did.
1) Remove the upper dashboard. It's not fun but it is completely do-able by someone with minor mechanical skills and patience. EVERYTHING comes off easily, if it seems stuck YOU ARE DOING IT WRONG.
2) Detach the blower assembly. 6 fasteners and a cable connector up top on the air recirculate actuator.
3) Observe your air vent position motor/gears. There should be two small white 1/6 gears behind the primary gear, the upper one is your broken friend.
4) you can now look down into the airbox and see the baffle.
5) FIND THE ******* BANANA PLUG THAT THE PREVIOUS OWNER DROPPED DOWN THE DEFROSTER, GOT SHAKEN LOOSE, AND JAMMED/BROKE THE CAM TO THE BAFFLE.
6) REMOVE THE OBSTRUCTING OBJECT.

Here is my solution, it's not pretty.

7) drill holes in the front of the baffle and feed wire up through the defrost vent, attach to the baffle allowing you to pull the wire to activate the front vents. Repeat with a wire guided to the front of the dash into the storage box in front of stick shift, this wire will be pulled to activate the defrost.

8) reassemble.

I wish I had better news. you will not be able to fully replace the box yourself and the quoted price from the dealership is $3700 (P+L).

Feel free to ask if you have more questions or need help with the dash.
 
#19 ·
Wow thanks for the outstanding reply!, I'm not exactly sure what we plan on doing at this point, my short term solution is remote start, and preheat the car before driving in winter, not the end of the world for summer. I suppose we drive our Excursion more.

Original owners nothing that I know of fell down there, it is however the wife's car.
 
#21 ·
I didn't take pictures. I was up against the clock with the storm moving in so I powered through it. Can't get the part out to print it. It's very much in there.

Step 1, do you have the factory service/repair manual? I found it floating around on this site.
 
#24 ·
Update my problem was the glue holding weather stripping on box melted and that caused door to stick closed and gear popped off that controls flow to dash and feet.
The dealer said I needed to replace whole box at a cost of $3000.00! Just a heads up dealers do not always offer the "best fix" they would rather replace than repair a friend who is a toyota mechanic who is old school found this simple fix just clean the glue off��...
He seen this happen before its commen problem.
If you look up under dash on passenger side you can see the box right behind the stereo and the door on box if black glue is seen smeared you will face this same problem clean all glue with alcohol before door glues shut.
 
#25 ·
My apologies for resurrecting this old thread, but I have a similar problem with my manual damper mode controls. The main white gear that actuates the dampers is broken, and ends up cock-eyed and won't turn. It has 3 claws that hold it in place and one has broken off. For the life of me, I can't find a part number for the gear. Originally there may have been some kind of retainer (screw, bolt, etc) that also held it in place...at this point i can't remember. I'll attach pictures. If anyone can help point me to a part number and source, I would greatly appreciate it.
 

Attachments

#30 ·
You may be able to find one in a junkyard for a lot less.
 
#32 ·
I can tell you exactly what happened same exact problem I have with my gear one clip snapped off...
I have a master Toyota mechanic friend and the problem is the glue they used on the heater box weather stripping it melts and the heater box door that diverts heat to the floor sticks and the gear breaks and your heat to the floor no longer works....
I know if you go up under dash on passenger side you can see the door try to lift it..
It will be glued shut which is why the gear broke the tab off trying to open the door..
He searched the Toyota parts mircrophish spelling???? Says gear is available ordered it but it was the wrong part!!!! With $140.00 price tag!!!!
Toyota needs to get this part I now have my heat set on defrost for the cold months..
I used baby powder on the glue to keep it from sticking which worked mine was very hard to unglue ****ty design!!!!
 
#33 ·
Just an update on my Rav, my mechanic was able repair mine, without any parts needed nothing broken , said something sticky was what caused it to stick and he cleaned it up and put it back together(gears were off and such) , been a couple weeks, I feel like its kind of sticky... time will tell iirc around 5 hours labor for my fix.
 
#36 ·
I've been following this thread to repair my 2007 RAV4 Limited with dual zone auto climate control.

Symptoms - blinking defrost light. Fan respond to panel controls. Vents doors do not respond to panel controls. No heat is delivered, ostensibly because of vent doors.

Checked the HVAC fault codes (21/24/97).

Sourced a used AC Amplifier - no change to symptoms or faults.

Cleaned the black glue out of the accessible vent doors - no change to symptoms or faults.

Removed all actuator servos - all motors respond to battery and contacts are clean.

Gears are not broken and vent doors respond cleanly to my actuation.

Any advice or next steps?

Thanks!
 
#37 ·
Have you deciphered the codes you got? Tried resetting them?
 
#39 ·
I deciphered the codes prior to my repair and after I replaced the AC Amplifier.

21/24 are solar sensors that I decided to ignore based on this discussion:


97 is BUS IC Communication malfunction. After following the steps below I replaced the AC Amplifier with one from a wreck.


There were no change in the codes after I replaced the AC Amp. I concluded the AC Amp is probably ok and proceeded to cleaning the vent door glue and checking the integrity of the servo motors (albeit the Toyota manuals indicate that limited bench testing is available for the servo-motor pulse controls).


Thanks!
 
#44 ·
I've tested a new harness with no resolution.

Error codes 21/23/97

Troubleshoot steps to date:

1. Tried AC Amplifier from wreck - no fix
2. Cleaned glue off vent doors - no fix
3. Tested all servos, function with 9v - no fix
4. Tested new harness - no fix
5. Cleaned contacts in servos - no fix

Next steps is finding a known good AC Amplifier (easy to remove from test car - servos are not so easy).
 
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