4-10
©
2012 Mobile Climate Control
T-348 Rev. 07/2012
1.
Cylinder Valve and Gauge
2.
Pressure Regulator
3.
Nitrogen Cylinder
4.
Pressure Gauge (0 to 400 psig = 0 to
27.22 bar)
5.
Bleed-Off Valve
6.
1/4 inch Connection
1
2
3
4
5
6
Figure 4-7 Checking High Pressure Switch
c. Connect an ohmmeter across switch terminals.
d. Set nitrogen pressure regulator higher than the up
per switch setting. (refer to paragraph 1.5.)
e. For a high pressure switch, close cylinder valve and
open bleed-off valve. Open cylinder valve and
slowly close bleed-off valve. The switch should
open, (no continuity) within required cut out tol
erance. Close cylinder valve and release pressure
through the bleed-off valve. As pressure drops,
switch should close, (continuity) within required
cut in tolerance.
f. For a low pressure switch, close cylinder valve and
bleed-off valve. Open cylinder valve to bring pres
sure above the cutout setting. Close the cylinder
valve and slowly open bleed-off valve. The switch
should open, (no continuity) within required cut
out tolerance. Open cylinder valve and increase
pressure by closing the bleed-off valve. As pres
sure increases, switch should close, (continuity)
within required cut in tolerance.
g. Replace or re-install switch and reconnect wiring.
4.11 FILTER-DRIER
4.11.1 To Check Filter-Drier
The filter-drier (see Figure 4-8) must be changed if
the drier is partially restricted or service has been
performed on the refrigerant system. Check for a
restriction by feeling the inlet and outlet lines of the
filter-drier. If the outlet side feels cooler than the
inlet side, then the filter-drier should be changed
1
5
4
3
2
3
1. Filter--Drier Inlet Solenoid Valve
2. Valve Service Port
3. Hex Nut (ORS)
4. Filter--Drier
5. Filter--Drier Outlet Service Valve
Figure 4-8 Filter-Drier Removal
4.11.2 To Replace Filter-Drier
a. Perform a low side pump down. Refer to para
graph 4.5.1, (steps a. to c.)
b. Turn the driver's A/C switch to “OFF” position.
c. Frontseat the filter-drier outlet service valve and
place a new filter-drier near the unit for immediate
installation.
d. Remove the filter-drier clamp.
WARNING
The filter-drier may contain liquid refrig
erant. Slowly loosen the ORS hex nuts to
avoid refrigerant contact with exposed
skin or eyes.
e. Using two open end wrenches, slowly crack open
the ORS hex nuts on each side of the filter-drier.
Remove the filter-drier.
f. Remove seal caps from the new filter-drier. Apply
a light coat of compressor oil to the O-Rings and
seat in the grooves of the filter-drier.
g. Assemble the new filter-drier to lines ensuring that
the arrow on the body of the filter-drier points in
the direction of the refrigerant flow (refrigerant
flows from the receiver to the evaporator), and
that the O-Rings have remained in place. Finger
tighten ORS hex nuts.
h. Tighten the filter-drier ORS hex nuts using two
open end wrenches.
i. Evacuate the filter-drier and lines by connecting a
vacuum pump as shown in Figure 4-6. Evacuate to
500 microns.
j. Backseat (fully close) the service valve port and re
place valve cap.
k. Test filter-drier for leaks.
l. Check refrigerant level.