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Noise from heater box

Discussion in 'Chevy Trucks' started by DieselSlug, Jan 16, 2014.

  1. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    Hello all,
    I have had an issue for a year or two now with something in my heater box. The issue has come and gone about 2-3 times and is back again.
    When I start the truck something in the box makes a "flapping" sound. This sound will go on for 20-30 seconds and then stop. But if I hit the recirc button it will stop, but then start again a few seconds later. It does the exact same thing when you shut the truck off.
    Its been doing this for 2 weeks now and is driving me nuts! Every time I start or stop the truck everyone around me looks at me like its a ticking time bomb.
    You can hear it in the passenger cowl area too under the wiper as well as inside where it is the loudest.
    I wonder if it has anything to do with the recirc door as when iI mess with the buttons it stops the noise momentarily. All heater functions work normally.
    I am going to try and get a video of this tonight to help explain.
    Thanks!
     
  2. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    That is one thing I forgot to put in. The blower motor functions perfectly. So the flapping is independent from the motor. Will flap at any speed.

    Also maybe sounds like plastic teeth slipping? If there is any in there.
     
  3. Greenstar lawn

    Greenstar lawn Senior Member
    Messages: 405

    What kind of truck? My Chevy has been doing this too and it's driving me crazy.
     
  4. Greenstar lawn

    Greenstar lawn Senior Member
    Messages: 405

    Oops just saw this is in the Chevy forum
     
  5. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    1994 K2500 6.5L Diesel.
     
  6. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    I know. I'm desperate! I'm trying to spread this like wildfire to get any answers.
     
  7. Whiffyspark

    Whiffyspark 2000 Club Member
    from SOMD
    Messages: 2,402

    Does it have a blend door?
     
  8. Greenstar lawn

    Greenstar lawn Senior Member
    Messages: 405

    I hope someone can shed some light on this bc this noise is driving me insane. Mine also is the loudest when you start the truck up regardless of blower speed
     
  9. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    Yes it does. It has the fancy old school digital heater head unit.
     
  10. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    What are the stats on your rig? Same year?
     
  11. Greenstar lawn

    Greenstar lawn Senior Member
    Messages: 405

    Mines an 04 2500 hd
     
  12. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,963

    Have you actually taken out the blower motor and looked around inside?
     
  13. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

  14. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    No I haven't. Mainly because I heard that is a major pain to do. The motor could use some lube though, at low speed it squeaks a little.
     
  15. Greenstar lawn

    Greenstar lawn Senior Member
    Messages: 405

    I haven't looked around yet. Just turn the volume up higher on the radio lol
     
  16. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,963

    On a 94. It's not hard at all.
     
  17. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

    I'm going to see how much this part is and try to open it right up down there. This will be my chance to check out the blower motor also. Going to see if there are any how Tom's on motor removal.
     
  18. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,054

  19. Whiffyspark

    Whiffyspark 2000 Club Member
    from SOMD
    Messages: 2,402

    Yeah you can usually just pull the screws out the bottom and pull it out.

    Actuator is possible. Check inside the blower first. And check blend door if possible
     
  20. tuney443

    tuney443 PlowSite.com Addict
    Messages: 1,847

    Don't have any idea except obviously it needs a teardown for an inspection.I just want to say not to leave a bag of peanuts laying around in the cab.I have no idea how Mr Varmint got inside but he systematically was stealing my in the shell nuts and they got inside the HVAC.Almost everytime I put the blower on,especially on vent mode,a whole large nut with shell would either wack into the backside of the vent or I'd hear it in the squirrel[no pun intended] cage or both.Never saw just a bare nut,maybe he wasn't eating and only wanted to piss me off.Found them other places also including the other day in the larger rubber dirt ejector on my Dmax air box.