Thermo King UT-1200, Manual

Page: 158 / 169

Refrigeration Diagnosis
158
• • • • Restricted line on the high side
• • • • Restricted drier
• Defrost damper stays open
• • • Defrost damper stuck closed
• Suction service valve back seated
• • • • • • • Faulty Condenser Inlet Solenoid (CIS)
• • • • • Faulty Hot Gas Solenoid (HGS)
• • Loose or broken electrical connections
• • • • • Sensor out of calibration
• • • • Suction pressure gauge out of calibration
• Leaky receiver tank outlet valve
• • • Faulty Discharge Pressure Regulator (DPR)
• • • • • Faulty Suction Pressure Regulator (SPR)
• • • • Faulty Liquid Injection Solenoid (LIS)
• • • • • • • Faulty Purge Valve (PV)
• Faulty Condenser Check Valve
• • • • • • Faulty Receiver Tank Pressure Check Valve
Rapid c
yc
ling between Cool
and H
eat
Unit c
ools
in
Heat and Defr
os
t c
yc
le
Unit heat
s in Refrigeration (Cool) c
yc
le
High head pres
su
re
Low head pr
es
su
re
No head pr
es
su
re
High s
uc
tion pres
su
re
Low s
uc
tion pres
su
re
No s
uc
tion pres
su
re
Unit operating i
n a v
ac
uum
Rec
ei
ver s
ight glas
s empty
Suc
tion li
ne fr
os
ting bac
k
Unable to pump down s
ys
tem
Unable to pul
l v
ac
uum in l
ow s
ide
Unable to hol
d v
ac
uum
in low s
ide
N
ois
y co
m
pre
ss
or
Unit not refr
igerating
Unit not heati
ng or
defros
tin
g
Sym
p
to
m
Possible Causes