Take control of your cabin airflow with the Dorman - OE Solutions HVAC Blend Door Actuator (604-921). This actuator drives the main air door inside the HVAC case, moving it so the system can direct air to the settings you select. It drops in as a direct replacement for a long list of 1996-2023 Chevrolet and GMC full-size vans and 2003-2009 medium-duty trucks, including the Chevrolet Express 1500/2500/3500/4500, Express Cargo and Passenger, C4500-C8500 Kodiak, GMC Savana 1500/2500/3500/4500, C4500-C8500 Topkick, and the 2005-2008 Isuzu HTR/HVR and 2006 Isuzu HXR (all engines) — see the Buyer's Guide tab for the full list.
- Direct-fit replacement: built to install like the original air door actuator on the listed applications.
- Position specific: this is the MAIN air-door actuator; vehicles often use several HVAC door actuators, so review the application notes to confirm it matches the location and function of the one you need to replace.
- Rotary switch activation, plastic construction: uses a rotary activation type.
- Built to last: designed and tested to strict standards to help resist wear and electrical burnout for reliable operation and long service life.
Backed by a team of experts and engineers in the United States and more than a century of experience. Country of origin: China. Package contents: 1 air door actuator.
Interchange: 1996840 · 89018674 · DA1339 · ADA631
Manufacturer part number 604-921.
This part cross-references / interchanges with the following part numbers:
Frequently Asked Questions
What does this blend door actuator do?
It drives the main air door inside the HVAC case, moving it so the system directs airflow according to the settings you select on the dashboard controls.
Will this fit my vehicle?
It's a direct-fit replacement for the listed 1996-2023 Chevrolet Express and GMC Savana vans, 2003-2009 Kodiak/Topkick trucks, and 2005-2008 Isuzu HTR/HVR plus 2006 HXR. Check the Buyer's Guide tab for the full list.
My vehicle has several actuators — is this the correct one?
This is the MAIN air-door actuator. Vehicles often use multiple HVAC door actuators, so review the application notes to confirm the position and function match before ordering.
What other part numbers does it replace?
It interchanges with 1996840, 89018674, DA1339 and ADA631.
What are signs this actuator may need replacing?
Common signs include a clicking or knocking noise from the dash area or air that won't switch to the mode you select. Diagnose the cause before replacing, as other parts can produce similar symptoms.
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