1. Check the Fuse: Begin with the simplest check. Consult your owner's manual to locate the fuse for the blower motor. Check it with a multimeter or by visually inspecting it for a blown element.
2. Locate the Blower Motor Resistor: The resistor is typically located behind the glove compartment or under the dash, often near the blower motor itself. Access might require removing the glove box. You'll likely need to consult a repair manual or online resources (like a YouTube video specific to a 1997 Chevy Astro) to pinpoint its exact location.
3. Inspect the Blower Motor Resistor: Once you've located it, visually inspect it for any obvious signs of damage, such as burning, melting, or broken connections. If it looks damaged, it needs replacement.
4. Test the Blower Motor Resistor (Optional but Recommended): A multimeter can confirm whether the resistor is faulty. You'll need to know the resistance values for each speed setting (these are usually available in a repair manual or online). If the resistance readings don't match the specifications, the resistor is bad.
5. Check the Blower Motor: While less likely, a failing blower motor can also cause this issue, especially if it's making unusual noises. Testing the motor requires more advanced electrical knowledge and tools, often involving checking voltage at the motor itself while trying to run it on high.
6. Wiring and Connections: Examine the wiring and connectors leading to the blower motor resistor and blower motor for any loose, corroded, or broken wires. Repair or replace as needed.
7. Switch: In rare cases, the blower motor switch itself could be faulty. This is less likely than a bad resistor, but it's a possibility if all other components check out.
Important Considerations:
* Repair Manual: A repair manual specific to your 1997 Chevy Astro van will be invaluable for pinpointing component locations, testing procedures, and wiring diagrams.
* Safety: Disconnect the negative battery terminal before working on any electrical components.
* Replacement Parts: Obtain a replacement blower motor resistor from an auto parts store. Ensure you get the correct part number for your vehicle.
If you're not comfortable working with car electrical systems, it's best to take your Astro to a qualified mechanic. Replacing the blower motor resistor is usually a relatively straightforward repair, but improper work could lead to further damage.
