There is a "thumping" noise

Sounds like water hammer. Air in the pipes. Lower volume of water out of the sprayer isn't enough to initiate the hammer. Try shutting the water off to the house and draining the pipes.
Open the offending faucet and turn the water back on this should eliminate the air in the pipes.

to reduce the 'thumping' noise, open the supply valves more. If they are already at maximum, you may have a restriction further up the supply lines. Thumping is typically caused by unbalanced flow around the seat and washer, usually caused by restrictions.

you have air in line
1. turn off water under sink
2 turn faucet on full
3. turn on valves under sink water will sputter then run solid
Hope this helps mike

sounds like a pen cap fell down the defrost vent ??? just a pain you have to open things up. just went through this with a sterling truck but the vent flap broke the rear hinge and was flopping around inside.

Usually this is caused by a binding blend or mode door. The actuator keeps trying to move it and can't. Locate the exact source of the noise. Then disconnect the actuator and try opening and closing the door by hand.

Hi,
It is called expansion and contraction...
When you turn the water on and off the pipe will move just a bit....
When the pipe is warmer it is a bit longer and it does not hit whatever is causing the thumping...
When the pipe is colder it shrinks just enough to hit....
This causes the thumping when cold...
It is not hurting anything... just annoying...

heatman101

The assembly is pictured here in this diagram http://www.deltafaucet.com/customersupport/documentation/21925LF.html?document=pd

and the spot unscrews from the faucet body and pulls straight up.

The thump comes from one of several areas. Air pressure in the hand sprayer is one.

But I suspect that you need to check your shut off valves. Old style (non ball) valves fail during this event. There is a little washer that deteriorates, over time....
Then you need to install a faucet, you shut the valves and the little washers either break or come loose. When they break, little pieces go up and clog the faucet.
The other failure is they partially block flow afer coming loose, and cause a thump, like what you describe. To fix, shut off main water in the house and DRAIN what you can. Best to replace with whole new valve, but next best is to replace the guts, unscrew and take to hardware store and get new stem and guts. Inspect the seat, often they get damaged and pitted. Nor necessarily an issue on this install, as the valve in normally open...

hello, you may have a air pocket in the line try shutting of the water supply and then sqeeze the handle and slowly turn the water supply back on with the hose handle squeezed on till the air is forced out, hope this helps

sounds like the bearings are bad or something is catch in the fan