Odor Diagnosis

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

Step	Action	Yes	No
Symptom Definition: Odor originating or noticed through the heater and air conditioning evaporator and blower module and duct system. Cause of Odors A musty odor caused by mold or mildew build-up on the carpet, evaporator core, heater core, passenger compartment air filter, or the heater and air conditioning evaporator and blower module or ducts. A coolant odor cause by leaking heater core, or external coolant leak. An oil odor cause by engine oil leaks, transmission fluid or power steering fluid leaks. Odors caused by the surrounding external environment. Examples: other vehicles, trees, flower, or animals.
1	Have you verified the customers concern and identified the odor?	Go to Step 2	Go to Step 5
2	Is the odor a musty smell?	Go to Step 6	Go to Step 3
3	Is the odor a coolant smell?	Go to Step 11	Go to Step 4
4	Is the odor a oil smell?	Go to Step 15	Go to Step 5
5	Sit inside the vehicle. Close all of the doors and windows. Start the engine. Allow the engine to idle to normal operating temperature. Select the maximum blower speed. Select the Instrument panel air outlet mode. Select the coldest temperature setting. Cycle through all of the blower speeds, modes and temperatures to define what type of odor is present. Musty smell Coolant smell Oil smell Does the odor have a musty smell?	Go to Step 6	Go to Step 11
6	Inspect the air inlet grille and passenger compartment air filter for signs of water and debris. Is there debris or signs of water present?	Go to Step 7	Go to Step 8
7	Remove any debris and replace the passenger compartment air filter. Is the repair complete?	Go to Step 19	-
8	Inspect for water leaks and a wet carpet. Is there a water leak or wet carpet?	Go to Step 9	Go to Step 17
9	Perform a water leak test to identify area of the leak. Inspect for the following areas for water leaks: Blockage of the evaporator and blower module drain upper hose. Water leaks around the windshield Open body seams, grommets and seals Sunroof drain tubes Leaks around the door seals Is a leak present?	Go to Step 10	Go to Step 17
10	Repair the leak as necessary. Is the repair complete?	Go to Step 19	-
11	Does the odor have a coolant smell?	Go to Step 12	Go to Step 15
12	Inspect the external cooling system for leaks and repair. Loss of Coolant (LSY) Was there external coolant leak found?	Go to Step 19	Go to Step 13
13	Inspect for coolant leaking inside the vehicle or for a film build-up on the windshield. Is the condition present?	Go to Step 14	Go to Step 19
14	Replace the heater core. Heater Core Replacement Is the repair complete?	Go to Step 19	-
15	Does the odor have an oily smell?	Go to Step 16	Go to Step 19
16	Inspect the engine leaks: For LSY engine, refer to Oil Leak Diagnosis For L3B engine, refer to Oil Leak Diagnosis For LF4 engine, refer to Oil Leak Diagnosis Inspect for transmission fluid leaks: For MQA or MHU automatic transmission, refer to Fluid Leak Diagnosis For M5N automatic transmission, refer to Fluid Leak Diagnosis For MG9 manual transmission, refer to Transmission Fluid Leak Diagnosis Repair any oil or fluid leaks. Is the repair complete?	Go to Step 19	-
17	Perform the odor correction procedure. Odor Correction Is the musty odor present.	Go to Step 18	Go to Step 19
18	Replace the air conditioning evaporator. Air Conditioning Evaporator Replacement Is the action complete?	Go to Step 19	-
19	Operate the system in order to verify the repair. Did you find and correct the condition?	System OK	Go to Step 5