Sharp AF-05CML Service Manual page 11

HEATING THE TUBING
Direct the torch flame so that the larger tube receives most of the heat. Silver
solder flows at 1200˚F and silfos flows at 1300˚F.
Heat all around the tubing.
The flame is composed of two cones, a smaller inner cone (pale blue) in colour
and a much larger outer cone. The hottest part of the flame is at the tip of the
inner cone. The flame should be directed at the joint with the tip of the cone just
touching the surface of the tubing. Figure 3 and 4.
DEHYDRATING SEALED SYSTEM
Many services feel that since air conditioners run with evaporator temperatures above 33˚F, moisture will not present a
problem. Nothing is further from the truth. Oxygen in moisture plus the heat produced during compression will react with the
refrigerant oil to produce harmful acids in the system which will break down motor winding insulation, create sludge and pit
component parts, reducing efficiency of the air conditioner and shortening the life of compressors.
There it becomes mandatory that good dehydrating practices be adhered to at all times.
Proper hook up procedures as shown in Figure 5 must be used in order to pull and good vacuum from the system.
The use of a good vacuum pump is very important so that the boiling point of any water in the system will be lowered to a
point where it will vaporize and be expelled from the system in the form of vapour.
Type of evacuation methods
1. Piston Type Compressor No good.
System parts must be above 110 ˚F.
2. Rotary Vacuum Pump Disadvantages.
Low CFMC. 4 oil gets dirty.
3. Single State Vacuum Pump will not clean oil.
Oil must be changed often.
4. Two Stage Vacuum Pump will reach 50 microns.
First stage is below atmospheric pressure.
Moisture is removed into second stage which works
up to atmospheric pressure thus keeping oil clean.
Manometer cannot be read to 1/2 mm. Micron
gauge reads from 25,400 microns to 0.
Composition of Torch Flame.
ELECTRIC
VACUUM
GAUGE
TO RELATED SERVICE
VALVE OR PROCESS
TUBES OF THE UNIT.
LARGE DIAMETER
BRAIDED VACUUM
HOSES
Hook up for Evacuation and charging
11
OUTER CONE
HOTTEST PART
OF FLAME
INNER CONE
TORCH STEM
Figure 4
DIAL-CHARGE
CHARGING CYLINDER
LOW SIDE HIGH SIDE
GAUGE GAUGE
HIGH VACUUM
MANIFOLD
HIGH VACUUM PUMP
Figure 5
AF-05CML