Friedrich KUHL R-410A Service Manual page 64

HEAT / COOL ONLY ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS
P o r b e l m
Bad indoor ambient thermistor
Room temperature
Fan speed too low
uneven
Opened door, windows, etc.
(Heating cycle)
ATSF (room air sampling feature) disabled
P o r b e l m
Bad outdoor coil thermistor
Unit will not defrost
(Heat pump
only models)
Temperature below 32°F/ 0°C
P o r b e l m
Exhaust or fresh air door open
Dirty fi
Unit undersized
Does not heat
adequately
Outdoor coil thermistor or electronic control
board defective
Heater hi-limit control cycling on & off
Shorted or open supplementary heater
I c n
P o s s b i e l C a
P o s s b i e l C a
P o s s b i e l C a
t l r e
r o e r t c w r i n i g
u s e
Check error codes. Replace as needed.
Set at higher fan speed.
Close doors, windows, etc.
Enable ATSF
u s e
Replace thermistor.
• On heat pumps with electric heat: no action needed
• On model YSM10: do not operate below 32°F/ 0°C
• If outdoor air temp is higher than freezing, check
reversing valve, electric coil, outdoor thermistor,
refrigerant circuits, etc.
• For proper operation: correct as needed
u s e
Check if operating properly. Instruct customer on
proper use of control
C e l a
Check heat rise across coil. If unit operates
effi ciently, check if insulation can be added
to attic or walls. If insulation is adequate,
recommend additional unit or larger one
Check alarms (error codes). Replace thermistor
or electronic control board.
Check for adequate fan air across heater. Check
for open hi-limit control.
Do ohmmeter check.
C h e
Possible Solution
Possible Solution
Possible Solution
n s a e r o c m m e n d e d n i O w
k c a p i l p a c b e l w r i n i g d a i g a r
n e s ' r M a n u l a
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