* Clogged Condensate Drain: This is the most common cause. The AC system produces condensation as it cools the air. This water normally drains out through a small tube or hose. If this drain becomes clogged with dirt, debris, mold, or mildew, the water will back up and overflow, leading to leaks inside the vehicle.
* Drain Hose Disconnection: The drain hose might have come loose or become disconnected from its fitting. This will prevent the condensation from draining properly.
* Evaporator Core Leak: While less common, a leak in the evaporator core itself (the part of the AC system that cools the air) can also cause water leaks. This is a more serious problem requiring repair or replacement of the evaporator core. This often involves a refrigerant leak as well.
* Condenser Leak (Less Likely): While less likely to cause *interior* leaks, a leak in the condenser (the part outside the vehicle) *could* indirectly lead to an interior leak if the refrigerant also leaks into the evaporator housing and freezes, blocking the drain.
How to troubleshoot:
1. Locate the Drain: First, you need to locate the condensate drain. It's usually a small hose or tube that exits the AC unit somewhere near the firewall on the passenger side. You may need a flashlight.
2. Check for Clogs: Inspect the drain for blockages. You might be able to clear a clog by gently using compressed air or a long, thin wire to poke through any debris.
3. Check for Disconnections: Examine the drain hose for any loose connections or breaks. If it's disconnected, reconnect it securely.
4. Inspect for Leaks: Carefully inspect the area around the evaporator core (you’ll need to access this, possibly involving removal of parts under the dashboard - best left to a professional unless you're very experienced). Look for any signs of moisture or dripping beyond the normal condensation.
When to Call a Professional:
If you're uncomfortable working on your vehicle's AC system, or if you can't locate the drain or find a simple fix, it's best to take your Trailblazer to a qualified mechanic or AC specialist. A leak in the evaporator core is a significant repair that's best handled by a professional. They have the tools and expertise to diagnose and fix the problem correctly, preventing further damage. Additionally, AC systems contain refrigerant, which is harmful if improperly handled.
