GM Service Manual Online
For 1990-2009 cars only

Poor Heater Performance - keywords cold defrost floor heat HVAC low temperature vent

Subject:Poor Heater Performance

Models:2006 Chevrolet Silverado
2006 GMC Sierra
With 6.6L Engine RPO LBZ



The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Owners may comment on poor heater performance. During normal diagnostics, it may be noted that both heater hoses are cold. This concern may be cause by the heater hose being pinched/kinked at the lower radiator hose.

Recommendation/Instructions:

To correct this concern, drain the coolant system and reroute the heater hose to eliminate the pinch/kink.

Note: There is a white line on the heater hose. This white line should be centered to the front of the hard tube.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.