Ticking Sound In Dash

[ek02]

My 2002 Trailblazer has a soft ticking sound in the dashboard at times. It has the rhythm and sound of an old windup clock. The sound is not always there, but is mostly heard at idle. It is not the noise made by an A/C mode door actuator. I have been through two of those already. It may be under the hood, but it sure sounds like it's in the dash just to the right of the IP. It does not change with engine speed. Everything on the vehicle works perfectly. My wife asked if the turn signal was on, that's what it sounds like. Any ideas?

 

[Blckshdw]

If you're able to, when you catch it happening, pull over and pop your hood, just to see if it's something in there that you're just able to hear from the cabin.

 

[Bow_Tied]

I had it happen on a '99 Jimmy where the turn signal relay would click like that, randomly. It never lit the lights unless I had used the turn signal. It was dirt or crap in the switch mechanism making just enough contact to make the relay click. G/L

 

[IllogicTC]

It would be helpful to pinpoint the exact location of the tick. A stethoscope could be of help here. I would have thought gauge ticks of death (the tach can even make very minor adjustments that are nearly imperceptible to the eye, and therefore appears to be hovering over the same point, mine does that).

 

[ek02]

I will have to remove the panel under the left side of the dash and give a listen with a stethoscope or a piece of heater hose to zoom in on the noise. I hear it in the left center A/C vent fairly clear, and right behind the fuel gauge. It did it all day today and did it with the engine off, key on. Turning the A/C off did not change it. I had a Silverado company truck that had the same noise in the dash, but only sometimes. I'll post the reason as soon as I get time to diagnose it.

 

[Bow_Tied]

Did the noise start after disconnecting the battery?

 

[C-ya]

I can hear my gauges on a cold morning waiting at the bus stop with my daughter. Not sure if it is one noisy one or multiple ones. They all work, so it hasn't become a priority yet.

 

[sunliner]

my gauges have always made a lot of racket. I just accepted it as one of the quirks of the vehicle. they still work except for the oil pressure gauge but I think the sensor is flaky rather than the gauge itself

 

[ek02]

I have not heard the noise the last few times I drove the TB. I only drive it once in a while or to tow my boat. It may be temperature related since it has been cooler in S. Fl. and it has not done it.

 

[ek02]

I drove the TB for a while today and the ticking sound has turned into more of a swooshing sound, but still in the same spot behind the dash. I tried different A/C settings and discovered that when I push the defrost button, the noise goes completely away. It may be one of the mode actuators. I wonder if any of them would normally be running all the time? Everything on the vehicle works the way it is supposed to. The HVAC system has all functions including proper temp control. I need to get the time to pull the cover off the bottom of the dash and try to put my hand on the defrost actuator to see if it is running.

 

[Bow_Tied]

I wonder if that would be the blend door that mixes the air for temperature....just guessing.

 

[TGFB87]

From experience, if the noise goes away if you switch the AC controls to anything other than "Auto" it is a blend door.
We had ours replaced right before the warranty was up.
The sound came back. We either ignore it or switch to a different AC mode.

 

[ek02]

I replaced the blend door actuator twice. It made a noise like stripped gears when it went. I have been too busy to fool with it, but I will eventually find out what it is. Thanks for the replies.