The no heat at idle condition is normally caused by low coolant level and air in the cooling system. Top off the engine coolant if it is low, then follow the below procedure to get trapped air out of the cooling system.
#PIC4301C: Poor Heat At Idle - (Feb 6, 2009)
This PI was superseded to update model years. Please discard PIC4301B.
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.
These cars also have problems with the remote keyless entry transmitters and receivers. The bulletin below addresses that concern.
#07-08-52-001C: Remote Keyless Entry (RKE) Inoperative, Poor Range, Tire Pressure Monitor (TPM) Message Displayed, Remote Vehicle Start (RVS) (Replace/Reprogram RCDLR, Replace Antenna and Transmitters) - (Aug 27, 2009)
This bulletin is being revised to update the Parts Information. Please discard Corporate Bulletin Number 07-08-52-001B (Section 08 - Body and Accessories).
Important: This bulletin does not apply to vehicles built after the following dates:
Some customers may comment about one or more of the following conditions:
Any of these concerns may be caused by an internal fault with the transmitters and/or the Remote Control Door Lock Receiver (RCDLR) software/hardware.
DO NOT REPLACE THE BCM.
Tip The existing antenna is grounded into another wiring harness. It will be necessary to pull the existing harness and antenna up near the C-pillar in order to disconnect the antenna from the other wiring harness.
Important: When programming a new or existing RCDLR, the programming instructions in SI must be followed.
Important: Refer to the parts catalog using the VIN of the vehicle being serviced to identify the correct part numbers.
Antenna -- Remote Control Door Lock Receiver (Impala with RVS Only)
Antenna -- Remote Control Door Lock Receiver (Monte Carlo Only)
Transmitter -- 4 Button with Trunk
Transmitter -- with Remote Vehicle Start System
Receiver -- Remote Control Door Lock ( with RKE and without RVS)
Receiver -- Remote Control Door Lock ( with RKE and RVS)