texdave
Junior Member
- Joined
- Mar 28, 2024
- Posts
- 4
- Reaction score
- 2
- Location
- texas
- First Name
- tex
- Truck Year
- 1976
- Truck Model
- C10
- Engine Size
- 350
Truck: 76 GMC C25 Suburban w/454 + 3 speed auto + factory air conditioning
When I'm driving and have the air conditioning on (Max or Normal mode, at any Fan speed) I hear what sounds like a short sucking sound every 40 seconds or so. It gets louder as the RPMs go up and I don't believe I hear it at all when at idle. I don't hear that noise when the A/C is off or when I switch the mode to Vent.
Here's a link to a video I took that shows this in action:
Is this a vacuum leak on a line that goes to the HVAC controls or something else? Appreciate it if you can point me in the right direction.
When I'm driving and have the air conditioning on (Max or Normal mode, at any Fan speed) I hear what sounds like a short sucking sound every 40 seconds or so. It gets louder as the RPMs go up and I don't believe I hear it at all when at idle. I don't hear that noise when the A/C is off or when I switch the mode to Vent.
Here's a link to a video I took that shows this in action:
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.Is this a vacuum leak on a line that goes to the HVAC controls or something else? Appreciate it if you can point me in the right direction.
