Evaporator Core

Finding leaks in the evaporator core is one of the most difficult tasks in detecting leaks. In order to leak test the core, complete the following steps:
1. Turn the blower fan to the high position for 15 seconds or longer.
Then, turn the blower fan to the OFF position.
2. Wait 10 minutes.
3. If the blower fan power module or resistor block is accessible, remove the module.
4. If the blower fan power module or resistor block is not accessible, inspect the condenser drain tube for moisture.
If the condenser drain tube is dry, use the drain tube in conducting the test.
5. Insert the probe of the leak detector into the power module/resistor block opening or the condenser drain tube.
A solid alarm indicates a leak.
6. If possible, visually inspect with a flashlight the core face for the evidence of refrigerant oil.
On R-134a systems, the lubricant is water soluble, so evidence of oil is unlikely, even with a leak.