AC Making High Pitch Sounds/Control Unit Not Working Intermittently?

1998 BUICK RIVIERA
182,000 MILES • 3.8L • V6 • 2WD • AUTOMATIC
Avatar
JUANEMMANUEL
  • MEMBER
  • 63 POSTS
Started up the car and after a little while of idling, this high pitch sound comes on that sounds like it's coming from the dashboard. The AC comes on but the climate control buttons do not work at all. Then after shutting off the car and restarting, the buttons work again but the high pitch sounds comes back and goes away, intermittently. Any ideas?
Dec 8, 2025 at 6:23 AM
Advertisement
Avatar
STRAILER
  • CERTIFIED EXPERT
  • 53,855 POSTS
Thanks for the video, I can say out of all my years, I have not heard that kind of noise coming from the HVAC system. Can you tell if it is coming from the HVAC control head or the blower motor? I will forward this to the expert forum to see what we get from the other experts.
Dec 9, 2025 at 10:07 AM
Avatar
JUANEMMANUEL
  • MEMBER
  • 63 POSTS
I really don't think it's from the blower motor. It sounds like it's coming from the middle of the dash. And coupled with the fact the buttons were not working at all suggests control module.
Dec 9, 2025 at 10:09 AM
Advertisement
Avatar
STRAILER
  • CERTIFIED EXPERT
  • 53,855 POSTS
The system is fully electronic, so I don't think it is a vacuum leak, I would say the HVAC programmer is the problem. I would unplug it it and see if the noise is still there. Check out the images (below). Let us know how it goes.
Image (Click to enlarge)
Attached Media
Dec 9, 2025 at 11:02 AM
Avatar
JUANEMMANUEL
  • MEMBER
  • 63 POSTS
I'm sorry but where would the HVAC programmer be located on my car?
Dec 18, 2025 at 2:24 PM
Avatar
STRAILER
  • CERTIFIED EXPERT
  • 53,855 POSTS
This is under the dash on the passengers side behind the glove box. Let me know how is goes, Ken
Dec 19, 2025 at 10:34 AM