
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