Figure 13-19.Typical vacuum pump.
3. Reduce the flame when the reaction plate is red,
and adjust the top of the flame even with, or slightly
above, the reaction plate (just high enough to maintain
the cherry-red color).
Too high a flame will soon burn out the
4. Move the search hose slowly around the system.
Refrigerant R-12 is heavier than air, so move the search
hose under all parts to ensure accurate detection and
watch for the flame to change color. A pale blue color is
normal and indicates that there is no refrigerant leak.
Yellow or yellow-green indicates a small leak, purplish
blue indicates a larger leak.
If you do not find a leak, increase the system charge
by 50 percent. Add 1 pound to a 2-pound system; and 2
pounds to a 4-pound system. Repeat the detection check.
It is often necessary for you to overcharge a system to
locate a small or intermittent leak. If you find a leak
discharge the refrigerant from the system, repair the
damage, and recharge the system. Finally, recheck the
system after completing repairs.
When searching for leaks in an air-conditioning
system, you are looking very closely at all working
parts. Do not waste this time. Check for cracked or worn
hoses, loose electrical connections, broken wires, worn
drive belts, and loose component mounts. When you
detect any damage, make the needed repairs at the same
time as the inspection.
PURGING THE AIR-CONDITIONING
Anytime an air-conditioning system is discharged
and opened before it is returned to service, it must be
evacuated and recharged. To perform this operation, you
need certain tools, such as a vacuum pump (fig. 13-19),
a gauge manifold set (fig. 13-20), and a leak detector.
Figure 13-20.Gauge manifold set.