Knocking in dash

[jwlurie]

I have a random knocking sound in the dash of my 2004 Suburban 2500. It doesn't knock all the time, but when it does, it doesn't make a difference if the A/C is on or off. It sounds like it's coming more from the passenger side. It gets pretty obnoxious. Any ideas?

[JMoney02]

Could be several things, bracket that hits in a specific place when your on bumpy road, the cover for the heater core hitting against the front frame support fo the dash if someone had not returned all the screws to hold it in place. Now this just theory, not saying srews were removed.
1)Have someone drive the vehicle for you, take it a place that you know that it rattles all/most of the time.
2)Have the glove box removed so can have quick access to the area.
3)Automotive stethoscpoe will work well for this to diagnose, you can hold in in different area's and listen to see if you pin point the rattle.
4)No music, phones, windows up and this could take time and Murphy's Law, it may not rattle when you want it to.
5)May have to perform this several times to eliminate the obvious.....
Good Luck........

Two things that are a PITA in vehicles - RATTLES and ELECTRICAL problems, they suck....

Jeff