DeVilbiss DeVO/MC44-90 - Page 22

SECTION 7
SERVICE INSTRUCTIONS
or rising slowly, test sieve bed pressures. If it is
also low or rising slowly, then:
(1) Compressor reed valves, teflon ring or the
compressor itself may be defective.
(2) There is a severe leak in system.
(3) One or more of unit filters may be
occluded.
Check for air leaks using a leak detection
solution such as “Snoop” or “Search”. Also
ensure that the air intake filters or
compressor filter are not occluded. If no leaks
are found and filters are not occluded, com-
pressor must then be removed and repaired
or replaced.
To remove compressor:
1. Refer to Service Instruction B to open
cabinet covers. The back cover should be
completely removed to make it easier for
compressor removal. The front cover does
not have to be removed completely.
2. Remove hose clamp and compressor
intake hose (11 Fig. 14) from compressor
intake baffle.
3. Turn unit face down on work surface with
compressor directed upward.
4. Remove motor mount nuts (2 Fig. 21) and
washers (3 Fig. 21) using a 7/16” nut
driver.
5. Carefully place unit in an upright position
and disconnect the compressor quick-
connect terminal (15 Fig. 14) located
behind the compressor.
6. Loosen hose clamp (4 Fig. 19) and remove
the black rubber pressure exhaust hose (3
Fig. 19) from compressor fitting. This can
be accomplished more easily by carefully
lifting the compressor slightly upward
and outward while removing the hose.
7. Remove compressor from base assembly
and unscrew the four motor mounts (13
Fig. 14) from bottom of compressor so
that it can be placed on the work surface.
To inspect and/or replace internal compo-
nents:
1. Remove the four allen head screws (4 Fig.
25) that hold each compressor head (3 Fig.
25) in place. Remove both heads at the
same time.
10/87
20
2. Check for proper placement or damage to
the gaskets (6,21 Fig. 26) on bottom of
compressor heads. Replace them if they
are damaged.
3. Remove reed valve plates (7,17 Fig. 26).
There is a reed valve (8,20 Fig. 26) on each
side of the valve plates.
NOTE: Scratches or slight indentation on top
of the piston are normal. These are caused by
the reed valve.
4. The reed valves should be flush with the
valve plate. If it is broken, not flush with
valve plate, or foreign matter is detected
inside of the head, replace or clean the
reed valve.
To replace reed valve:
(A) Remove screw (9 Fig. 26) holding reed
valve (8 Fig. 26) in position on valve
plate and discard reed valve.
(B) Reed valves flex in only ane direction.
Place the new reed valve, by the
edges, between your thumb and
forefinger. Gently bend (approxi-
mately 1/8” (3mm)) to determine the
direction of flex.
(C) Place the concave side of reed face
down on valve plate.
(D) Position the new reed so that it is
centered and completely covers the
hole in the valve plate.
(E) Place the nylon keeper and metal
retainer on the reed valve. (Reed
valves on the bottom of valve plate
have only the metal retainer.) Secure
these with the reed valve screw.
5. Check for proper placement or damage of
the rubber o-ring (13,15 Fig. 26) on the
bottom of the valve plate. Replace if it is
damaged.
6. Remove sleeves (12,16 Fig. 26) by pulling
upwards and inspect teflon rings (4,23
Fig. 26) on pistons. Replace if badly worn
or damaged.
To replace teflon ring:
(A) Remove screws (3 Fig. 26) from top of
piston (2 Fig. 26) so that retainer plate
can be removed. Discard defective
teflon ring.