Two problems related to defogger have been reported for the 1998 GMC Sierra. The most recently reported issues are listed below.
The consumer has been experiencing problems with windshield wiper motor. When turning the windsheild wipers on, the motor makes a lot of noise. The manufacturer has yet to be contacted. Vehicle also has the following problems: engine coolant tank and brake master cylinder are leaking, brakes and fuel pump are noisy, and passenger side defroster does not flow enough air.
Right windshield defroster did not adequately clear sides of the ice snow and frost due to the low volume of air coming from the right defroster louver. Nlm.