A/C vent not opening

[Carlos Serrano]

My 99 R129 driver side corner vent by the door won't open, no air comes out of it, the others work perfectly.Anybody knows whats going on,do I have to replace the dial? how do you do that?How do you get to it, is it a big deal to repair or maybe the problem is somewhere else.
Thanks

[bobterry99]

I suggest running diagnostics to read live values and see what is going on. You do this by turning the ignition ON and setting the temperature to 72 degrees. Next you press the REST button and hold it for 6 or more seconds. The controller should be in diagnostic mode at this point as confirmed by the display alternately displaying "72" and the menu item number "01".

You can monitor the input from the thumbwheel controlling the vent by accessing menu item number 61. You access the different menus in sequence by pressing the blower motor "+" button. Item 61 displays the input voltage the controller is receiving from the thumbwheel control. This voltage should vary continuously between about .7 and 4.3 as the thumbwheel is moved. If it does not, there is probably a problem with the thumbwheel potentiometer or the wiring to the controller.

If the thumbwheel checks-out okay, you may have a vacuum leak. Post back if you need help with that.

[Carlos Serrano]

Thanks
I'll try to get to it as soon as I get back to town,I'll let you know how it turns out.I sure appreciate the help

[Carlos Serrano]

I choose to ignore the problem with my vent too long I'd run the diagnostic on #61 and the values are .8 to 4.0 and as I ran the test the vent open for 15 seconds when I turn the dial from close to open several times. I've tried the test with the ignition switch on and with the car runing and the same results, not quite sure I'm doing it properly since the menu values change from the code no. to what I think is the value constantly and also the temperature setting flashes in between. I should have follow thru when I first ran this thread but then it was cool weather;now I need that vent I'll appreciated any help you can provide

[Carlos Serrano]

Does anybody knows the proper name for the bank of electromagnetic solenoids behind the dash in the passenger side ? My guess is that the solenoid that opens that particular vent is malfuntioning not allowing vacuum to that flap. does anybody knows wich one it is and how to test it, the plastic cover can be removed clearly exposing this solenoids.
Anybody with experience with this parts. Any help will be appreciated.

[bobterry99]

The name of the bank is "Y11". The line which goes to the vent is question is labeled "10/11". I would get a vacuum pump and apply 1 bar to the line and see if it maintains the vacuum. You can rent such a pump from Autozone or buy one from them for about $20.

I had a problem with a vent. It turned-out to be a hairline crack in one of the nipples on Y11. I repaired it with a little epoxy.

[Carlos Serrano]

I think we are on the right track bobterry, hopefully is not a faulty solenoid it looks like if it is the whole assy. needs to be replaced ,any idea how the test the solenoid itself ? I'd taken the plastic cover off before for another reason about a year ago and one of them was getting pretty warm,I'll try the vacuum test first and just hope that's what it is. Thank you for yuor help.

[Carlos Serrano]

Tested vacuum at port 10 / 11 no problem there. This assembly is very hot #4 and #6 are extremly hot , they buzzed and click constantly , I'm worried to say the least. I unplug the vacuum line from 10 / 11 and the vent opened up, evidently this one is vacuum closed not open.does anybody have an idea of how much a 1298002878 valve cost I sure like to know.