Where is the heater switch valve located on Dongfeng trucks

[Darin]

There are four main reasons for engine cylinder gasket failure: Burnout between two cylinder edges: Due to insufficient engine power, the vehicle exhibits poor driving performance and acceleration. When removing the air filter, intense noise can be heard at the intake pipe during engine idle. Burnout area connecting to water jacket holes: Manifests as bubbling in the radiator, boiling over, and white smoke from the exhaust. Burnout area connecting to oil passages: Causes some engine oil to enter the cylinders and burn, resulting in blue smoke from the exhaust. Burnout area exposed to the environment: