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SLOW LEAK IN SYSTEM
O n f o r c e d a i r m o d e l s , l o n g r u n t i m e w i l l
be n ot i c e d du ri n g t h e e a rl y stag e s of a
lea k . A s t h e re f ri g e r an t co n tin u e s to e s-
ca p e, b o t h co m p a r tme n ts w il l g ra d ually
wa r m u p a n d t h e co mpr esso r wi ll r u n
c o nt i n u ou s l y . Th e f re e ze r w il l p ro bab ly
wa r m u p f i rst .
INCORRECT REFRIGERANT
CHARGE
T he se al e d u n i t ma y h ave too mu ch refr i-
gerant (overcharged system) or too little
re fri g era n t ( un d e r ch a rg e d system). Th e
f o ll o w i n g p ar a g ra p h s wi l l i n fo rm yo u on
ho w t o re co g n i ze a syste m wi th th e se d e -
fects.
An overcharged system may have a frost
b a ck c o nd i ti o n a p p e a rin g ou tsi d e th e in-
s ul a t io n sl e ev e o n t h e su ctio n l i n e a t th e
c ab i n e t re a r. W h e n t h e co mp re sso r sto p s,
t he f ro st m e l t s a n d dri p s o n th e fl o o r . A
h e at ex ch a n ge r se p a ra ti on wi l l a l so ca use
t his s ym p t o m .
An u n de r c h a r g e d syste m d ep e n d in g on
t he d e g re e o f u n d e r ch a rg e , wi l l o p e ra te
with te m p e ra tu re s a b o ve n or ma l a nd th e
c om pr e s s or r u n t i me w i ll b e i n cre ase d .
T h e g r ea t e r t h e u n d e rch arg e , th e h i gh er
th e t emp e ra t u re wi l l be a n d th e lo n g e r th e
r u n t i m e .
An u n de rc h ar g e d sys te m mu st b e p u rg e d ,
ev a cua t e d , a nd r e c h a rg e d w ith the p rop er
am ou nt o f re f ri g e ra nt. Be fo re re ch a rg in g,
h owe v e r, t e s t f o r re f rig e ra n t l e a ks.
DEFECTIVE COMPRESSOR
A co mpressor which is not pumping ade-
q u at ely will not cool eff ect ively. A ll cool-
ing surf aces m ay be cover ed w it h a thi n
film of f rost , but the t emperat ure will not
descend to the cut-out temperature of the
c o n t r o l , e v e n w i t h c o n t i n u o u s r u n n i n g o f
th e compressor.
Be cause these symptom s are similar to a
r efr igerant leak, it is advisable t o t hor-
o u ghly leak test at this point. lf no leak is
ind icated, install gauges and chec k the
o p erat ing pr essures. lf t he high side pres -
su res ar e lower t han those specified, and
lo w side pressures are higher than speci -
fie d, suspicions of an inef ficient com pres -
so r will be confirm ed and t he com pr es sor
m u st be replaced.
PRESSURE UNLOADING IN SYSTEM
Th e compressor may st all and cycle on
the overload protector if an attempt is
m a de t o restar t t he unit immediately after
it has st opped. This is because t he refr i-
g e r a n t p r e s s u r e i s h i g h o n t h e c o n d e n s e r
sid e and low on the evapor ator side. W hen
t h e c o m p r e s s o r s t o p s r u n n i n g , t h e l i q u i d
slo wly passes through the capillary tube
an d t he pr essur es are said to be "unload-
i n g " . P r e s s u r e u n l o a d i n g i n t h e s y s t e m
m a y t ake f rom 3 t o 6 minut es.
PULL DOWN OVERLOAD
lf the cabinet compart ments are w ar m
wh en the com pr essor st art s, the "pull
d o wn" may t emporar ily overheat the
co m pressor and cause cycling on t he ov-
e r load pr otector .
3-6
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