2001 Cadillac Deville dts and the blower motor works when you tap it on bottom of housing?

A blower motor that only works when tapped suggests a problem with the motor itself, specifically its internal electrical connections or the commutator (the rotating part with the contacts). The tapping is likely jarring loose a connection that's become intermittent due to age, wear, or corrosion. Here's a breakdown of the likely causes and what you should do:

* Worn Brushes: Blower motors have carbon brushes that wear down over time. When they're worn, they lose contact with the commutator, causing intermittent operation. This is a very common cause of this symptom.

* Loose or Corroded Connections: The wiring connections to the motor itself might be loose, corroded, or broken. The tapping is temporarily restoring contact.

* Failing Commutator: The commutator can wear down or become pitted, leading to poor electrical contact with the brushes.

* Motor Winding Issues: Less likely, but a problem within the motor windings themselves could be causing the intermittent failure. This usually requires motor replacement.

What to do:

1. Safety First: Disconnect the negative battery terminal before doing any work on the blower motor.

2. Access the Blower Motor: This usually involves removing the glove box or parts of the dashboard. Consult a repair manual specific to your 2001 Cadillac DeVille DTS to find the correct procedure.

3. Inspect the Connections: Once you access the blower motor, carefully inspect all wiring connections for looseness, corrosion, or damage. Clean any corroded connections with a wire brush and electrical contact cleaner. Tighten any loose connections securely.

4. Inspect the Blower Motor: If the connections look good, you'll likely need to replace the blower motor. Visually inspecting the motor itself for obvious damage is difficult without disassembly.

5. Test the Motor (with caution): If you're comfortable working with electricity, you *might* be able to test the motor with a multimeter to check for continuity and resistance (but this requires some electrical knowledge and is not recommended for someone unfamiliar with it).

Recommendation:

Unless you're comfortable with car repair and have the tools and knowledge to diagnose and replace the blower motor, it's best to take your Cadillac to a qualified mechanic. Replacing the blower motor is often more straightforward than extensive troubleshooting, especially since you'll likely need to access it through the dashboard. The cost of professional repair will be less than the frustration of a DIY attempt that might not succeed.