How do you replace a heater blower relay on a 1990 Cadillac Fleetwood brougham?

To replace the heater blower relay on a 1990 Cadillac Fleetwood Brougham, first disconnect the negative battery cable to ensure safety. Locate the relay, which is typically found in the fuse box under the dashboard or near the engine compartment. Remove the old relay by gently pulling it out, then insert the new relay in the same position. Finally, reconnect the battery and test the blower to ensure it operates correctly.