Coolant shut off valve exists or not exists?

[Rawze]

If they are installed, then they would be on the passenger side near the back of the engine somewhere... blocking off the hoses that feed the A/C heater cores.

Shutting them off will not effect the coolant flow to the DEF system... and if this was the case for the Volvo, then I could only assume someone installed them in the wrong place?. - does not make any sense.

Draining the coolant system.. and then re-filling it after the repairs are done.. and then pulling a hard vacuum on the system to remove all trapped air and prevent a distorted liner/engine failure, is the proper steps for doing coolant system work on most of the vehicle and engine.