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Rear HVAC System Conditions Owners of some 2003-06 Cadillac Escalade, Chevrolet Suburban and Tahoe, and GMC Yukon models with RPO CJ2 and C69 may have one or more of the following concerns: - Intermittent ticking/clicking noise from rear HVAC system - Unable to control rear system temperature - Unable to change rear system modes The HVAC actuators may hunt for the correct commanded position. This cycling can cause a clicking or ticking noise. Overtravel of the HVAC system control doors can cause one or more of the listed system conditions. If overtravel occurs, a DTC sets and the door goes to a preset default position. When a system door defaults, that door stays at the default position until the code is cleared. Clearing the code allows the door to operate properly until the overtravel condition re-occurs. B0434 Auxiliary (rear) temperature door B3764 Auxiliary (rear) mode door Replace the auxiliary (rear) HVAC control module (part number listed in the table below). This module contains a new calibration to compensate for the actuator overtravel condition and the hunting/clicking and ticking noises. All 2003-06 with CJ2 and C69 Module, Auxiliary HVAC control 15832319 When using the new auxiliary HVAC control module, you may notice a slight increase in rear blower speed (approximately 50 rpm). If the customer comments that the increase in blower speed is objectionable, the blower control module may be replaced with the second design blower control module to correct the slight increase in blower speed. Tahoe, Yukon, Escalade (short wheelbase) Second design rear blower control module 89024926 Suburban, Yukon XL, Escalade ESV (long wheelbase) Second design rear blower control module 89018846 TIP: The revised auxiliary HVAC control module should not be used unless one or more of the codes listed above is set. The revised control module will not correct any other DTC or A/C performance concern.

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Source

Source: GM TechLink — Communication from a manufacturer to dealers (summary published by a government agency)
Reporter type: Manufacturer
Source reference: 2007-02-01
Country / market: US
Language: en
Document version: Version 2 (2 held)
Note on the source: Copyright General Motors Corporation. No licence is stated. Held as the headline and short quoted passages with the issue named and linked; the articles themselves are not stored or shown.

Dates

Incident date: Unknown
Received by source: 2007-02-01
Added to the source's file: Unknown: not returned by the source API
Issued / published: 2007-02-01
First observed: 2026-10-06 08:58 UTC (initial bulk load)
This version fetched: 2026-10-08 14:58 UTC