GMW GMW15775 PDF

Note: Nothing in this standard supersedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose. The purpose of this test is to determine:

In the case of the variable capacity compressor, whether the Pneumatic Control Valve adequately protects the evaporator from condensate freeze.

In the case of fixed capacity compressor systems whether the control of the compressor cycling (clutch control) adequately protects the evaporator from condensate freeze.

In the case of an Electronically Variable Displacement Control (EVDC) or electrically driven compressor systems whether the capacity control (either displacement command or compressor speed command) adequately protects the evaporator from condensate freeze.

Foreword. This test procedure is intended to be used to collect data at three times during Heating Ventilation and Air Conditioning (HVAC) system development.

As a test technique (with potentially more limited test points) to verify the optimal location of the refrigerant control sensors (Evaporator Air or Fin Temperatures, refrigerant temperature probes or refrigerant pressure transducers).

As a test technique to develop initial calibrations with a proposed sensor placement and production intent control design that will provide robust protection from evaporator condensate freeze under most applicable conditions expected to be encountered for the vehicles intended usage.

As a vehicle-level test to perform final system verification around evaporator condensate freeze with production intent sensor designs/placements, controller, software and calibrations under a robust set of vehicle operating conditions.

Applicability. This test procedure is intended for use on either HVAC system test benches or full vehicle tests in Climate tunnels. The following conditions must be met for valid results of the testing.

Test must be conducted with a representative Air Handling Conditions at the Evaporator Air Inlet and Exit (typically this means testing with a complete and representative HVAC Module).

Test must be conducted with a representative Air Flow Conditions at the Condenser Air Inlet and Exit Typically this means testing with a complete and representative Condenser Radiator Fan Module (CRFM).

Test must be conducted with production intent Compressor and Refrigerant Expansion Devices.

Test must be conducted with production intent Refrigerant Controls software and calibrations as well as representative refrigerant control sensing devices (Evaporator Air Temperature Sensors, High Pressure transducers, Low Pressure Switches or transducers, etc.).

Test must be conducted with representative refrigerant plumbing (length, diameters and bends production representative).