Model 05G Compressor Maintenance; Removing The Compressor - Carrier CAPRI-280 Operation And Service Manual

3. Loosen one TXV bulb clamp and make sure area
under clamp is clean.
4. Place temperature thermocouple in contact with the
suction tube and parallel to the TXV bulb, and then
secure loosened clamp making sure both bulbs are
firmly secured to suction line. (See Figure 4-5).
Reinstall insulation around the bulb.
5. Reinstall evaporator access door being careful to
route thermocouple sensing wire outside the
evaporator.
6. Connect an accurate low pressure gauge to the 1/4"
port on the suction service valve or install a manifold
gauge set. (Refer to section 4.3.)
7. Start bus and run on fast idle until unit has stabilized,
about 20 to 30 minutes.
NOTE
When conducting this test, the suction pressure
must be at least 6 psig (41 kPa) below the
expansion valve maximum operating pressure
(MOP). Refer to section 1.3 for MOP.
8. From the temperature/pressure chart, determine the
saturation temperature corresponding to the
evaporator outlet pressure. (See Table 4-4.) Add an
estimated suction line loss of 2 psig (13.8 kPa) to the
number taken at the compressor.
9. Note the temperature of the suction gas at the
expansion valve bulb. Subtract the saturation
temperature determined in step 8 from the
temperature measured in this step. The difference is
the superheat of the suction gas.
10. Monitor the superheat over a five minute period and
record the maximum and minimum readings. Add
the maximum and minimum readings and divide by 2
to determine superheat. The superheat should be
10F to 12F.
c. To Adjust Superheat
NOTE
It is not recommended to adjust thermal
expansion valves unless absolutely necessary.
The procedure is very time consuming.
Therefore, it is highly recommended that the
expansion valve be replaced rather than
adjusting.
If adjustment is necessary, perform the following procedure:
1. Pump down the load side of the system. (Refer to
section 4.4.)
2. Remove capscrews and note relative position of cage
assembly. (See Figure 4.5.) Lift out power head and
cage assemblies while maintaining position of the
cage assembly. Turn/rotate
counterclockwise to decrease superheat setting or
clockwise to increase superheat setting. Each full
turn will change superheat setting by 1_F (0.56_C).
3. Check, clean and remove any foreign material from
the valve body, valve seat and mating surfaces.
T-283
4. Reinstall power head and cage assemblies using new
5. Tighten capscrews.
6. Evacuate and dehydrate. (Refer to section 4-6.)
7. Open filter-drier inlet valve (liquid line service valve)
8. Run the coach for approximately 30 minutes on fast
9. Check refrigerant level. (Refer to section 4.7.1.)
10. Check superheat setting. (Refer to section 4.11.b.)

4.12 Model 05G COMPRESSOR MAINTENANCE

4.12.1 Removing the Compressor

If compressor is inoperative and the unit still has
refrigerant pressure, frontseat suction and discharge
service valves to trap most of the refrigerant in the
system.
If compressor is operative, pump down the system.
(Refer to section 4.4.)
a. Turn main battery disconnect switch to OFF position.
b. Slowly release compressor pressure.
c.
d. Tag and disconnect wiring to the high pressure and
e. Remove four bolts holding compressor to base
f.
g.
cage assembly
4-6
gaskets.
and all service valves.
idle.
Remove bolts from suction and discharge service
valve flanges.
low pressure cutout switch, unloaders and clutch.
Attach sling or other device to the compressor and
remove compressor from the coach through the rear
access door.
Remove the three socket head capscrews from both
cylinder heads that have unloader valves installed on
the 05G compressor. Remove the unloader valve and
bypass piston assembly, keeping the same capscrews
with the assembly. The original unloader valve must
be transferred to the replacement compressor. The
plug arrangement removed from the replacement is
installed in the original compressor as a seal. If piston
is stuck, it may be extracted by threading a socket
head capscrew into top of piston. A small Teflon seat
ring at the bottom of the piston must be removed.
NOTES
1. The service replacement 05G compressors
are sold without shutoff valves. Valve pads
are installed in their place. The optional
unloaders are not supplied, as the cylinder
heads are shipped with plugs. Customer
should retain the original unloader valves
for use on the replacement compressor.
2. The piston plug that is removed from the
replacement compressor head must be
installed in the failed compressor if
returning for warranty.
3. Do not interchange allen-head capscrews that
mount the piston plug and unloader, they
are not interchangeable.