Poor Heat at Idle

This PI was superceded to update model years. Please discard PIC4301A.

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

Poor heat at idle, however, if the engine RPMs are raised the concern no longer occurs.

Note: Be sure to follow all SI safety procedures and caution notices.

1. With the engine cooled off, remove the coolant pressure cap.
2. Remove upper heater core hose from the metal pipe on the engine.
3. Add coolant to the metal pipe, until full.
4. Raise the rubber portion of the heater core hose as high as it will go with it still attached at the heater core. Using a funnel, add coolant until the hose is full.
5. Reconnect the heater core hose.
6. Start engine, have assistant raise the RPMs to about 1500 to 1700 RPMs, top coolant off at engine, then before lowering engine RPMs, install the coolant pressure cap.
7. Fill coolant reservoir as necessary, then check the heat at idle.

Note: If the vehicle returns for the same complaint perform the cooling system draining and refilling procedure outlined in SI, document ID 1783911.

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.