some vents not working, what actuator do I need?

[mrjean]

l cycled the modes and these r the results. Also its the same whether I have the blower on high medium or low.

Front vent only-lots of air
Floor vent with front defrost- air at floor only (strong around high gas pedal, bit of air at defrost. Per paper I placed on above defrost I could tell its leaked air coming out)
Floor only-air at floor (same as above)
Floor and front vent (air on front vent only no air on floor)
Front defrost- air at floor, no air at defrost (Same as floor vent with defrost above)
Recirculate- works on anything that has front vent mode. Blinks on all others. Same results as above in regards to air flow.

Sometimes I hear a "whine" sound coming from passenger side dash when I turn on the air system.
Also, would the driver/passenger actuator have any effects on air flow or just temp regulation?
So yea...now it sounds like mode actuator more tham defrost. But idk...thats why im here.

 

[mrjean]

Anybody?

 

[The_Roadie]

I was on a business trip yesterday, but I'm shocked nobody else chimed in.

I assume you've seen my classic illustration that's been posted a hundred times here and on the OS? 2002 actuators were different part numbers, IIRC. The usual parts places should sell you the right stuff if you look it up by model year.

In any event, you may have two problems. One of them is definitely the defrost actuator, from your clues. If the airflow mode actuator (floor / dash vent selection) is bad, the defrost actuator is worse. Change that one first.

The driver's and passenger side TEMP actuators only affect the temp, but where the airflow goes.

 

[mrjean]

So u def think both the mode and defrost actuators are shot?

 

[The_Roadie]

Any reason you need a definitive diagnosis before going in and changing the defrost unit first? I drove around a week without a dash and except for the radio being missing, it was fine.

 

[mrjean]

Well per my symptoms it def sounds like the mode and defrost actuator are bad. Now heres the kicker, otber than old age it seems like an unplug of the battery is making these fail. I have to chanve some sensors that req the neg bat terminal to b disconnected. Should I do my work first amd then change the two actuators I need?

Oh and and I have a tb ext....does the whole dadh come out easily? Im guessing it would be simpler to change the actiators with the dash out.

 

[The_Roadie]

A battery unplug or accidental discharge is the MAIN way that actuators fail. Due to a flawed GM recalibration process that a control module memory loss triggers. New actuators seem to less likely to die. There are no guarantees in this process.

Taking the entire dash out takes just over an hour, and isn't required for all actuators. Just take off as many panels as you need to get at the actuators you have to change.

 

[mrjean]

hey roadie...so finally got around to working on this now. have the time and money for parts.
from this post and the prev one about mode actuator (gives me headache) i have decided that yes i will buy the defrost and mode actuator.
since i have a 2002 the parts are different i guess and with different parts comes different names.

after combing multiple pages of info i have come to the agreement that part 604-115 is the mode or air flow mode actuator.
now, what the hell is the part number for the defrost actuator? since this is a 2002 is a diff part number. autozone has like a gazillion different actuators for me to choose from.

604-115 main unit air distribution mode
604-130 auxiliary unit temperature
604-106 main unit temp right
604-126 air inlet
604-111 main unit temp left

 

[mrjean]

could anybody jump in on this? i am getting the mode 604-115..however i dont know what part the defrost is. my local auto parts doesnt either since it doesn thave the exact name.

i think the defrost actuator is 604-111...could anybody confirm?

 

[The_Roadie]

Nalley GMC parts lookup says GM 89018677 is the thing, but as you discovered, 2002 were different and I've never successfully tracked down the definitive list for that mongrel year. GM rushed it to market and messed up a LOT of designs they fixed in 2003+.

 

[mrjean]

that prat number is equal to doorman 604-126...says that Blend door actuatorAir inlet.
i thought that the defrost and left temp (driver) actuator were the same...Gosh im so confused!

i alrady bought the mode 604-115..now since im going to be there i need to get the defrost to just get it out the way.

 

[mrjean]

bump for the defrost actuator on the 2002 tb ext

 

[filthyfingers]

I'm in the same boat. 2002 Envoy NOT EXT though. Very hard to get good cross reference information. Wimpy airflow out of the upper far right and upper far left vents. Wife says as she advances the temp control (manual slider) nothing happens until about three quarters of the way up. Then the airflow although still weak, gets hot fast. Blower speed control works fine. Went through the HVAC B fuse pull routine - no change. Auto Zone isn't much help and Rock Auto says Temp door Right is 604-106 and Temp door Left is 604-111.

I guess the only way to be sure is to pull out the suspect modules and use the GM part numbers for cross reference. Gonna be a pain. But when mama ain't comfortable...

 

[The_Roadie]

Wimpy airflow out of the upper far right and upper far left vents.

IIRC, the outboard vents are controlled just by the rotary dial adjacent to them. Only the center dash vents are turned on and off by the airflow mode actuator. Have you turned the blower on high and turned those dials to see if they affect airflow?

And on the temp sliders, do both passenger and driver's side have the same behavior? Try moving each one individually.

 

[filthyfingers]

IIRC, the outboard vents are controlled just by the rotary dial adjacent to them. Only the center dash vents are turned on and off by the airflow mode actuator. Have you turned the blower on high and turned those dials to see if they affect airflow?

And on the temp sliders, do both passenger and driver's side have the same behavior? Try moving each one individually.

Thanks for your insight. I've been offline and will be for a few more days. I recall that the outboard vent dials are wide open. I will cycle them both and vary the temp sliders and report back. If necessary I can change out the "dash controller". I have a spare.

 

[cyberpunk]

Any reason you need a definitive diagnosis before going in and changing the defrost unit first? I drove around a week without a dash and except for the radio being missing, it was fine.

roadie i am sorry but when i read your post above and saw the picture i started laughing right away(and now my wife thinks i am nuts officially), but only because i know your pain i promise.

the only difference in my case is that i have the dual temperature climate control system.

 

[filthyfingers]

IIRC, the outboard vents are controlled just by the rotary dial adjacent to them. Only the center dash vents are turned on and off by the airflow mode actuator. Have you turned the blower on high and turned those dials to see if they affect airflow?

And on the temp sliders, do both passenger and driver's side have the same behavior? Try moving each one individually.

SOLVED? I noticed a small coolant leak. Found that the clamp at the thermostat was loose and the reservoir empty. Radiator looked full. Tightened the clamp and added a second clamp for good measure then inspected the small hose from the reservoir to the filler neck. It was clogged at the reservoir end. Cleaned the res, flushed the rad. Symptoms all gone. Thanks again!