Blower Noise Diagnosis - Without A/C

Blower Noise (part 1 of 2):

Blower Noise Diagnosis (2 0f 2):

TEST DESCRIPTION
A constant air rush noise is typical of all heater systems when operating on "HIGH" blower. Some systems and modes may be louder than others. If possible, check a similar vehicle to determine whether the noise is typical or excessive. For diagnosis of excessive blower noise, refer to Charts (parts 1 and 2).