Thermo King – Heat Exchanger Test for Internal Leaks

Purpose: To test the heat exchanger for an internal high side to low side leak.
NOTE: To prevent refrigerant loss to the atmosphere, recovery equipment must be available to perform this test.

Test Procedure
1. Install a calibrated gauge manifold on the compressor.
2. Pump down the low side and adjust pressure slightly positive so the low side can be opened.
3. Remove the liquid line at the expansion valve inlet and plug or cap the line and expansion valve inlet.
4. Open the receiver tank outlet valve to pressurize the liquid line.

A rise in the service manifold low pressure gauge pressure indicates the heat exchanger is leaking internally. A heat exchanger with an internal leak must be replaced.

Returning the Unit to Service
1. Units with an internal leak in the heat exchanger may have the low side pumped down and the unit repaired.
2. Units with a good heat exchanger must have the refrigerant recovered from the receiver tank outlet valve using approved recovery equipment. Keep a slight positive pressure in the system.
3. Remove the plug or caps from the liquid line and expansion valve inlet.
4. Replace the liquid line drier.
5. Properly position all service valves, replace all service caps, leak check all fittings that were disturbed, and check the refrigerant level.

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