Service manual

9−18
62-11389
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START HERE
Is the unit operating in defrost?
Unit may be running old software. Upgrade
software from www.transcentral.carrier.com.
Did you find and correct the condition?
Check functional parameter settings for air flow.
Does the setting show high?
Check setpoint
System OK
System OK
Is setpoint +10.4F or
lower?
Is setpoint +10.5F or
higher?
Is return air temperature
equal to or colder than
setpoint?
Is selected probe temperat-
ure greater than 3.6F from
setpoint?
Is speed relay LED27
illuminated on the
micro? Did you find and
correct the condition?
Is there a voltage of 12V or
higher at QC3?
Check wiring for high resist
ance or shorted con
nections. Did you find and
correct the condition?
Check the ENSCU or FSA. Did you
find and correct the condition?
Review the test results with your
supervisor. If necessary, go to
the beginning of the tree and
test again.
Is there 12V or higher at the ENSCU
module pin 16 or FSA?
Figure 9−9 Micro Diagnostic Tree - Condition 5 - Unit Will Not Run In Low Speed