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 conditions are established: (a) Temperature at the air inlet is 30 — 35°C (86 — 95°F) (b) Engine running at 1,500 rpm (c) Blower fan speed switch set at high speed (d) Temperature control lever set at cool side HINT: It should be noted that the gauge indications may vary slightly due to ambient temperature conditions. 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) Each pointer of manifold gauge point to position A No. | Trouble | Condition | Position of Pointers 1 | Moisture present in refrigeration system | Periodically cools and then fails to cool | Between A and B 2 | Insufficient refrigerant | Insufficient cooling | C 3 | Poor circulation of refrigerant | Insufficient cooling | C 4 | Refrigerant overcharge or insufficient cooling of condenser | Does not cool sufficiently | D 5 | Expansion valve improperly mounted, heat sensing tube defective (opened too wide) | Insufficient cooling | D 6 | Air present in refrigeration system | Does not cool sufficiently | Low in D High in D' 7 | Refrigerant does not circulate | Does not cool (Cools from time to time in some case) | E 8 | Insufficient compression | Does not cool | F