Chapter 6REFRIGERATION AND AIR CONDITIONING
TEST
REMEDY
TROUBLE
POSSIBLE
CAUSE
Relocate thermostat to
a place more repre-
sentative of average
space temperature.
Space temperature
higher than thermostat
setting and thermostat
contacts are open.
B a d l o c a t i o n o f
thermostat.
Carefully read tempera-
ture at the sensing
element.
Thermostat out of ad-
Calibrate with good
Clean, adjust, or
justment or sticking.
thermometer.
replace the thermostat.
Cooling coil magnetic
valve not opening.
Solenoid Valve.
Valve sticking.
Replace solenoid coil.
Clean valve or adjust
pilots.
Space
temperature
thermostat lower than
thermostat setting and
contacts are closed.
Bad location of ther-
mostat (this will also ef-
fect cooling).
Test with reliable ther-
Move thermostat to a
mometer at location.
better location.
Space
temperature
lower than thermostat
setting and thermostat
contacts are open.
Cooling coil magnetic
valve stuck in open
position.
Stuck valve.
Disassemble and clean.
Replace solenoid coil.
Clean the valve.
Heating coil magnetic
valve stuck or bad
solenoid.
Test solenoid.
Test valve.
Thermostat or humidi-
stat time constant too
low, causing wide
deviation from set
point.
Sensing element fouled
with lint and dirt.
Examine.
Clean.
Electric heater does not
Controller contacts
Use test lamp to
cut out.
stuck.
determine.
Replace contacts,
springs or other parts as
found defective.
Electric heater does not
Overheat protection
cut in.
not reset or defective.
Place test lamp across.
Repair or replace.
Figure 6-13.Trouble diagnosis chart.
6-21