Checking of Refrigeration System with Manifold Gauge This is a method in which the trouble is located by using a manifold gauge. Read the manifold gauge pressure with the following established conditions: (a) Temperature at the air inlet is 30 — 35°C (86 — 95°F) (b) Engine running at 2,000 rpm (c) Blower speed set at high (d) A/C switch ON (e) Temperature control lever set at cool NOTE: It should be noted that the gauge indications may vary slightly due to ambient temperature conditions. 1. NORMALLY FUNCTIONING REFRIGERATION SYSTEM Gauge reading: Low pressure side 1.5 — 2.0 kg/cm² (21 — 28 psi, 147 — 196 kPa) High pressure side 14.5 — 15.0 kg/cm² (206 — 213 psi, 1,422 — 1,471 kPa) 2. MOISTURE PRESENT IN REFRIGERATION SYSTEM Condition: Periodically cools and then fails to cool Symptom seen in refrigeration system | Probable cause | Diagnosis | Remedy During operation, pressure at low pressure side some- times becomes a vacuum and sometimes normal | Moisture entered in refrig- eration system freezes at expansion valve orifice and temporarily stops cycle, but normal state is restored after a time when the ice melts | Drier in oversaturated state ↓ Moisture in refrigeration system freezes at expansion valve orifice and blocks circulation of refrigerant | (1) Replace receiver and drier (2) Remove moisture in cycle through repeated vacuum purging (3) Charge new refrigerant to proper amount