Pumping sound driver side dash

[Batiatus]

I did a search but couldn't find this exact issue.

 

There is a sound coming from what sounds like under the top of the dash on the driver side. It's consistent and repetitive. It sounds like two pumps then a release of air. "bomp bomp, psssst". I've turned the radio and HVAC off and it still does it. At idle in park and regular driving. Everything seems to be working ok and the truck runs fine. No MIL either.

 

Anyone else experienced this? 

[sefiroxx]

Sounds like air or blockage in the heater pipe. Hot water is always circulating through the dash, just no heat is obtained as the mode doors keep the airflow away from it.

Try flushing the system. You could reverse the heater pipes for a bit to backflush the heater core. Finally, if it is air in the system, park facing up hill, open the system (when cool) and run the engine for a bit until hot water level starts to rise in the surge tank

[garagerog]

Could very well be the HVAC system, but just for giggles to rule out brake booster noise you may be hearing, pop the hood, stick your head under there while someone else starts your vehicle.

[Supreme Pizza]

                                                                                                                        

[Batiatus]

I guessing it's something in the HVAC system. Now to try and locate it.

[sefiroxx]

If still there with ac off, then it's not Freon related. Per my earlier post, check heater lines.