Air buzzer not working

Yes

 

This is from CCMTA-NSC 11b;
d) low pressure warning Additional Inspection Procedure(s): Test The Operation Of The Low Air Pressure Warning device(s). Note: A visible warning device is mandatory (lamp or wig- wag). An audible warning device (buzzer or alarm)is optional, but must remain functional when OEM installed.

This is what fails inspection;
d) visible warning is inoperative or missing visible warning is not clearly identified,lamp lens is missing
-audible warning is inoperative or missing warning device fails to activate or operate continuously when air pressure is lowered below 414 kPa (60 psi)

So, in Ontario we use NSC 11b. Since the buzzer was OEM installed, it must work.

You don't need to replace the whole cluster. Remove the cluster, remove the back plate and the buzzer is on the right hand side.

I rarely see the buzzer fail. So look at junk yards for trucks and see if you can scoop an old cluster for the beeper.

Here is video of a guy showing where it is.