Checking High Or Low Pressure Switches; Filter-Drier; To Check Filter--Drier; To Replace Filter--Drier Assembly - Carrier AC310 Operation And Service Instructions Manual

5.10.2 Checking High Or Low Pressure Switches

WARNING
Do not use a nitrogen cylinder without a pres-
sure regulator
WARNING
Do not use oxygen in or near a refrigeration sys-
tem as an explosion may occur.
a. Disconnect wiring and remove switch from system.
b. Connect an ohmmeter across switch terminals. If the
switch is good, the ohmmeter will indicate no resist-
ance, indicating that the contacts are closed.
c. Connect switch to a cylinder of dry nitrogen.
(SeeFigure 5--4).
1.
2.
3.
Figure 5- -4 Checking High Pressure Switch
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
d. Set nitrogen pressure regulator higher than switch
cutout setting. (refer to paragraph 1.3.)
e. Open cylinder valve. Slowly open the regulator valve
to increase the pressure until it reaches cutout point.
The switch should open, which is indicated by an infi-
nite reading on an ohmmeter (no continuity).
f. Close cylinder valve and release pressure through
the bleed--off valve. As pressure drops to cut--in
point, the switch contacts should close, indicating no
resistance (continuity) on the ohmmeter.
g. Replace switch if it does not function as outlined
above.
04/08

5.11 FILTER-DRIER

1.
1.
2.
3.
4.
5.11.1 To Check Filter- -Drier
The filter--drier (See Figure 5--5) must be changed if the
system has been opened, (for any reason), or the filter
drier is partially restricted. Restriction can be identified
by either the outlet frosting or a temperature difference
between the inlet and outlet.
5.11.2 To Replace Filter- -Drier Assembly
Filter Drier replacement can be accomplished by
performing either one of the two procedures
recommended.
1. System operating, low side pump down (refer to sec-
4.
5.
2. System not operating (see below).
a. Turn the driver's A/C switch to "OFF" position.
6.
b. Frontseat the filter--drier service valves on both sides
of the filter drier.
c. Place a new filter-drier near the unit for immediate
installation.
d. Using two open end wrenches, slowly crack open the
connecting nuts on each side of the filter-drier as-
sembly. Remove the filter-drier assembly.
e. Remove seal caps from the new filter-drier. Apply a
light coat of mineral oil to the filter--drier connections.
f. Assemble the new filter-drier to lines ensuring that the
arrow on the body of the filter-drier points in the direc-
tion of the refrigerant flow (refrigerant flows from the
receiver to the evaporator). Finger tighten the con-
necting nuts.
g. Tighten filter-drier connecting nuts using two open
end wrenches.
h. Evacuate system (refer to section 5.7).
i. Backseat (fully close) both service valve ports and re-
place valve caps.
j. Check refrigerant charge (refer to section 5.8.1).
k. Remove Gauges.
5--5
2. 3. 4.
Figure 5- -5 Filter- -Drier Removal
Filter-Drier Inlet
Service Valve
Valve Service Port
Flare Nut
Filter-Drier
tion 3.4.1).
WARNING
The filter-drier may contain liquid refriger-
ant. Slowly loosen the connecting nuts and
avoid contact with exposed skin or eyes.
3.
2. 6. 5.
5. Liquid Line
Solenoid Valve
6. Filter-Drier Outlet
Service Valve
T-304