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Home >> Nissan-Datsun >> 2021 >> NV2500 HD S >> Repair and Diagnosis >> External Pages >> Different car >> Section 506 (Heater & Air Conditioning System) >> Symptom Diagnosis >> Both High- And Low-Pressure Sides Are Too Low >> Component Function Check

Component Function Check

WARNING: This page is about a different car, the 2019 Nissan NV3500 HD, 2019 Nissan NV2500 HD, and 2019 Nissan NV1500. However, it is still accessible from the selected car via links, so may be relevant.

Whenever system's high and/or low side pressure is abnormal, diagnose using a manifold gauge. The marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the standard (usual) pressure, however, differs from vehicle to vehicle, refer to Inspection  (Ambient air temperature-to-operating pressure table).

Both High- and Low-pressure Sides are Too Low 

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

SYMBOL

Both high- and low-pressure sides are too low.

SYMBOLGNSAC353A-353Courtesy of NISSAN NORTH AMERICA, INC.
  • There is a big temperature difference between liquid tank outlet and inlet. Outlet temperature is extremely low.
  • Liquid tank inlet and expansion valve are frosted.

Liquid tank inside is slightly clogged.

  • Temperature of expansion valve inlet is extremely low as compared with areas near liquid tank.
  • Expansion valve inlet may be frosted.
  • Temperature difference occurs somewhere in high-pressure side.

High-pressure pipe located between liquid tank and expansion valve is clogged.

  • Check and repair malfunctioning parts.
  • Check oil for contamination.

Expansion valve and liquid tank are warm or only cool when touched.

Low refrigerant charge.

Leaking fittings or components.

Check refrigerant system for leaks. Refer to Leak Test .

There is a big temperature difference between expansion valve inlet and outlet while the valve itself is frosted.

Expansion valve closes a little compared with the specification.

  1. Improper expansion valve adjustment.
  2. Malfunctioning expansion valve.
  3. Outlet and inlet may be clogged.
  • Remove foreign particles by using compressed air.
  • Check oil for contamination.

An area of the low-pressure pipe is colder than areas near the evaporator outlet.

Low-pressure pipe is clogged or crushed.

  • Check and repair malfunctioning parts.
  • Check oil for contamination.

Airflow volume is too low.

Evaporator is frozen.