nflguy

I have a 2007 Tahoe LT3. My AC fan speed fluctuates and it can happen when I'm sitting at a stoplight. Sometimes it goes up and down several times over the course of 60 seconds. Often times the max AC button will turn off on it's own.

I have brought it to the dealer four times! The first two times they said nothing was wrong. The third time they told me the aspirator was bad and they needed to program something. That worked for about a day. I brought it in a 4th time (today) and they told me they don't know what the problem is so they are going to replace the control head. Who knows if it will work. I worry that they are treating a symptom and not the cause of the problem. I don't want the true culprit to be revealed only after my warranty ends.

They added that fan speed fluctuation is normal. I think they just don't know. Like I said, I can drive down the block and on the way the fan speed will go up and down. I sit at a stop sign and the fan speed will go from a middle setting to low and the max ac will shut off.

I never use the auto function. I tried it once just to see if the fan speed still varies and it does. This is most noticeable when using level four (four bars) fan speed with max ac on.

I have also noticed that sometimes the secondary fan in the engine will come on right away and it's pretty loud.


Anyone that knows of a fix for this issue (or what can cause it) then please email me at jjdavis49@sbcglobal.net

in2pro

I have read somewhere in this forum I believe ZX posted it that the max or recirculation button will go off and on, on its own, it is a design to prevent the air in the passenger cabin from building up too much carbon monoxide, I believe he said it won’t stay on for more then 10 minutes.
Also make sure your passenger or the rear aux A/C isn’t set to something greater then what the driver has. My 07 will turn off the recirculation and will vary the speed of the blower in auto mode.

73shark

I thought ZX said that even in recirc, it still allowed ~10% outside air in.

in2pro

That maybe Marc, I don't remember the full context, I just remember the part about it cutting off by itself because I have seen mine do it and it annoys my wife as she likes it to be on all the time in traffic so she doesn’t have to smell anyone cigarette smoke.

nflguy

I don't use the auto function. Although I did try it once to see if the same problem happened and it did. I drive the car by myself a lot (no passenger air on or rear ac on) and yet i still get quite a bit of fan speed fluctuation. I will set it to level 4 (four bars) with max ac on and the air sounds like it does when your driving down the freeway on a very very windy day, only I'm just driving 10 miles an hr down a residential street with little to no wind.


What I'm curious about is that the first two trips to the dealer resulted in "Nothings wrong". The third trip and they told me the aspirator was bad and causing trouble and something in the engine needed to be programmed. That fixed the issue for about a day.

The problem returned and once again dealer is saying "Nothing wrong".

If nothing was wrong then what caused the aspirator to go bad after the 2nd visit?? They couldn't give me an answer.

They did tell me that another customer brought in a 2007 tahoe like mine for the same problem and they couldn't figure it out on that one either.

I'm gonna try a different dealer this week.


I wish I could find someone thatb had the same problem and what the fix was.

These damn dealers! I feel like I have to tell them the problem and the fix or else nothing gets done..Until my warranty expires ofcourse.

73shark

Anyone know what an "aspirator" is?

nflguy

It's located on the headliner above the drivers head. Looks like a little speaker. It's a temp sensor.

73shark

Oh that. I knew that it was what sensed the interior temp, just didn't know the name.