Tham khảo tài liệu 'cooling and lubrication system maintenance part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The engine will be running When you perform -the . cooling system tests so observe safety precautions Always refer to the organizational maintenance manual before removing air lines or performing any pressure tests. Drain air reservoirs before removing air lines or injury to personnel may result. 1 Testing the fan clutch. The fan clutch assembly can be easily tested by removing the outlet line that goes from the actuator to the fan drive clutch assembly fig 1-46 and installing an air pressure gauge at the outlet port of the actuator with the air pressure and engine temperature at the working level secondary system air pressure should be available at the outlet port. If system pressure is present but the fan does not operate the fan clutch assembly is defective. 2 Testing the air actuator. The air actuator is also very easy to test. Perform the outlet line test first if system pressure is not available remove the inlet line and install the air pressure gauge. Once again make sure the air pressure and engine temperature are at working levels. Secondary system air pressure should be present. If it is the air actuator either requires servicing or is defective. If the problem still exists after you have cleaned the actuator replace it. If system pressure isn t available the problem is in the secondary air system. Once again you must refer to the air system trouble-shooting section of TM 9-2320-272-20. Fig 1-46. Air actuator. 3 Testing for continuous fan operation. The system may have a malfunction that causes the fan to operate continuously. This is not nearly as serious a problem as the fan not running at all. If this should occur make sure the lockup bolt is not installed. Then remove the outlet line to the fan drive clutch assembly and check for pressure while the engine is cold. If pressure is present service or replace the air actuator. If air pressure is not present at the outlet line the fan drive clutch assembly is defective. 1-49 b. Testing the HMMWV fan drive
