06 Trailblazer issue

[foulpole18]

My wife's trailblazer when I drove it last time did some things I found strange. When sitting at a stoplight the rpms bounced up and down around where it normally sits. It almost felt like when the fan kicks on (a little vibration). It also did the same thing when I tried to open the power window that was frozen shut. Could it be the battery is going out?

Also when we were christmas shopping I noticed that when I would start it up it would make a sound like someone plugging the hose on a shop vac. It doesnt do it all the time, but is more noticeable when it is warm. Any idea what that is?

Thanks for the help guys I really appreciate it. Some of it I can do and other stuff I take in. With it being so cold it will go in.

Thanks again

Brian

[Jeremy airjer W]

I can tell you that the shop vac noise is normal and you should hear it as soon as the key is turned to the run position. It is the secondary air pump and it is located under the vehicle right under the drivers seat. If you don't hear it the check engine light will be on.

The other problem would depend on which motor you have. The straight 6 or the v-8?

[BoxMN]

Similar type thing, on our 05 trailblazer, I notice sometimes the lights will get slightly brighter. Sort of like what you are talking about, but I only notice the lights. The battery is new, and the instrument cluster has been replaced already. Any idea what this might be? Same thing?

Other than that, and a air leak on passenger rear window seal, all is good.

[foulpole18]

It's a 6 cylinder. I was just wondering about that shop vac noise because it seem much louder than normal. Could the cold be making it louder?

[deadeye]

I am pretty sure they have a TSB on the electric fan clutch having issues on those...

Dorman also makes a OE problem solver fan clutch..

[Jeremy airjer W]

If it was the fan than there should be a check engine light on. The PCM can monitor fan speed and knows if it is going to fast or to slow depending on what the PCM requests of it. So if the check engine light is not on than it is not broken, maybe

[See yup]

The secondary air pump will get water in it and freeze which will cause it's demise. I was told by a dealer that it rained to much that year and that is why it went bad getting water in it. So the idea is you can't let your Trailblazer sit in the rain because of bad engineering and placement of the secondaary air pump. You can drive without it but your emission system will probably fail quicker due to condensation not being forced through the system. The lights dimming and brightning is a known issue that Chevy does not have an answer for as of yet, You just have to live with it. When your dash cluster goes bad you can get it refubished cheaper than buying new. When your tranmission goes it will cost you about 1,900.00 to fix it the right way. The RPM'S will start to jump ever so slightly when going up hills-when it slips the RPMS will jump slightly and that will be your first notice. Take it in and get it looked at. Trailblazers have a flawed design in the tranmission that Chevy has been using for years and have not bothered to fix-just pass on the pain to their customers.

Trailblazer has a good ride and lots of space-they just become a money pit once it starts falling apart after 60,000 miles or so. Good luck- there are a number of forums that dicuss known problems with the trailblazer.

[foulpole18]

Not to worried about the transmission. It doesn't act up or slip at all. The rpms just bounced around a couple times while sitting at a light. Doesn't sound like a whole lot to worry about yet.

Thanks

Brian

[quickfish6]

It's not the Dan clinch cause the truck will not shift out of second gear if the fan clutch is bad. Very common problem though . I would say its not the transmission . Does one of the mounts on the electric fan look broken or loose? I would say the rpms jumping ariund mau be due to a tuneup is needed. How many miles are on this trailblazer? The shop back sound is the secondary air pump and its very common for the check valbe to do bad . I would trace the hose that goes from the air intake hose down and look for a check valve usually plastic and you can clean it out. No check engine light on at all ?

[foulpole18]

70,000 miles on it. It only seems to have done it that 1 time. Since it happened I've been driving it more than normal and the RPM bouncing hasn't happened since. I have also cleaned the garage and parked the truck inside and I haven't noticed the shop vac sound either. Could it be that something froze up in the cold and now that its thawed out it doesn't do it?

[quickfish6]

There is a check valve in the hose that goes from the air box down under the truck that has a check valve in it, The valve will hold water in it and freeze up. That is what is causing that sound. That is what you are hearing. I would call the dealership and see what the price is on it. Its good to change or it will wipe out that air pump.