# Thump a thumpa sound in the dash behind the radio

**URL:** <https://community.cartalk.com/t/thump-a-thumpa-sound-in-the-dash-behind-the-radio/10637>\
**Category:** Maintenance/Repairs\
**Created:** [February 14, 2008, 1:05am UTC](https://community.cartalk.com/t/thump-a-thumpa-sound-in-the-dash-behind-the-radio/10637 "2008-02-14T01:05:15Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Herb\_Vincent](https://avatars.discourse-cdn.com/v4/letter/h/ed8c4c/32.png) [@Herb\_Vincent](https://community.cartalk.com/u/Herb_Vincent)\
**Post date:** [February 14, 2008, 1:05am UTC](https://community.cartalk.com/t/thump-a-thumpa-sound-in-the-dash-behind-the-radio/10637/1 "2008-02-14T01:05:15Z")

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I have a '97 Lincoln Cartier Towncar which has 102000 miles and has been a dream, the best of 6 I have owned.  
  
 Last week when the weather turned hot, I started the car which had been parked outside and heard a thumping sound behind the radio, which has a tape player and a 10 cd player in the trunk.  
  
 The sound is like Thumpa, thumpa, thumpa and stopped after I turned on the A/C.  
  
 It seems to get shorter each time it happens  
  
 Any ideas ???

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**Author:** ![Beadsandbeads](https://avatars.discourse-cdn.com/v4/letter/b/c57346/32.png) [@Beadsandbeads](https://community.cartalk.com/u/Beadsandbeads)\
**Post date:** [February 14, 2008, 1:22am UTC](https://community.cartalk.com/t/thump-a-thumpa-sound-in-the-dash-behind-the-radio/10637/2 "2008-02-14T01:22:02Z")

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There is a motor that controls the blend door in the HVAC system. The door controls the air flow across the heater core or bypassing it. The door is stuck and the stepper motor keeps trying to move it. You probably need to have the door replaced. Eventually the thumping will stop after the motor burns out.

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**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\
**Post date:** [February 14, 2008, 11:41am UTC](https://community.cartalk.com/t/thump-a-thumpa-sound-in-the-dash-behind-the-radio/10637/3 "2008-02-14T11:41:53Z")

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```
Yea, most likely the blend door. I have also heard heater fans make noises like that. Try changing the fan speed (some run even when turned off) and see if it changes. In both cases it ends up disassembling it anyway.
```

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**Author:** ![Herb\_Vincent](https://avatars.discourse-cdn.com/v4/letter/h/ed8c4c/32.png) [@Herb\_Vincent](https://community.cartalk.com/u/Herb_Vincent)\
**Post date:** [February 14, 2008, 7:14pm UTC](https://community.cartalk.com/t/thump-a-thumpa-sound-in-the-dash-behind-the-radio/10637/4 "2008-02-14T19:14:53Z")

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Hi  
Thanks for your ideas… appreciate it.  
Herb Vincent