55
Section C - Components, cont’d.
C20.Sealed System
C20a.
Filter Drier & Capillary Tube
One mechanical problem you may encounter is refrigerant
flow restriction. There are two types of restrictions, high
side and low side. See Section C20c.
High side restriction will cause higher than normal amp
draw, drastically higher than normal high side pres-
sures, and slightly higher than normal low side pres-
sures.
Low side restriction will cause lower than normal amp
draw, drastically lower than normal low side pressures
and slightly lower than normal high side pressures.
A restriction that would not follow these basic condi-
tions is a liquid line restriction, which is in the high
side of the air conditioner. It will give the same results
as a low side restriction.
The most common restriction is the capillary tube or tubes,
and/or at the filter drier. If there is a restriction in the liquid
line, there will be a temperature drop from one side of the
restriction to the other side.
In the case of a capillary tube restriction, one tube would
be normal,( warm to the touch) and the restricted tube would
be cool or cold to the touch, and could even sweat if oper-
ated long enough.
A restriction in he filter-drier would cause a temperature
drop at the point of the restriction. A buildup of frost or sweat
could be evident if operated long enough.
Refrigerant leaks can occur from an improper weld, a bro-
ken line or other damage. Compressor oil will often be no-
ticeable at the location of major leaks.
Replace any parts that are found to be bad. Whenever a
component is replaced in the sealed system, or the sys-
tem has been opened to the atmosphere, a new filter-drier
and evacuation is required. If the unit was manufactured
without a filter-drier, one should not be added. Evacuate
the refrigerant system until it is dry (500 microns or less
reading on a vacuum thermistor gauge.)
C20b.
Recharging
Note:
The
Clean Air Act of 1990
set guidelines in regard
to recapturing or disposition of refrigerants. Check with lo-
cal authorities for proper handling or evacuation of refrig-
erants.
The equipment items needed to properly evacuate and re-
charge a sealed system are: a piercing type clamp-on
saddle valve; a braze -on processing valve; a core removal
tool; a process tube fitting; a set of compound gauges; a
vacuum pump; equipment to weigh a precise amount of
refrigerant; R-22 refrigerant; gas welding equipment; a R-
22 refrigerant leak detector and recapturing or recycling
equipment.
If you have not been properly trained in
sealed system repairs, do not attempt this procedure.
Note:
This is not a thorough sealed system repair training
program. For additional information or training, you may
want to attend a basic air conditioning course at your local
college.
To drain the R-22 refrigerant, attach a clamp-on saddle valve
on the low side process tube. If the air conditioner does not
have a low side process tube, attach a saddle valve at the
point where you will add a process tube.
Slowly drain the R-22 refrigerant by using recapturing or
recycling equipment. Do not leave the clamp-on saddle
valve on the unit as it will cause leaks.
If you are going to use the braze-on processing valve, once
the refrigerant has been drained, use a tubing cutter and
cut the tube near the end. Do this on both the low and high
side processing tubes.
FIG. C60
Manual
Compliments
of
Northwest
RV
Supply
Printed
From
http://www.nwrvsupply.com
