Carrier High Wall Duct Free Split System 38MVC Service Manual page 29

CHART 4 - - INDOOR UNIT COMMUNICATION ERROR SIZE 9K AND 12K
Check the wires and Check the wires and
connections between connections between
Indoor and outdoor units* Indoor and outdoor units*
Yes Yes
Reset main power and Reset main power and
restart system using remote. restart system using remote.
Problem persists? Problem persists?
Yes Yes
Measure Volts DC on Measure Volts DC on
outdoor TB between 1 & 3. outdoor TB between 1 & 3.
Ok?** Ok?**
No No
. .
Replace outdoor board. Replace outdoor board.
* Make sure wires are connected per connection diagrams. Failing to do that will result in a communication error.
** There is a 2 to 3 minute window to take the measurement before the diagnostic light is on again. ** There is a 2 to 3 minute window to take the measurement before the diagnostic light is on again.
No No
Fix connection or Fix connection or
replace wiring replace wiring
No No
No further action is No further action is
required required
Measure Volts DC on Measure Volts DC on
Yes Yes
indoor TB between 1 & 3. indoor TB between 1 & 3.
Ok?** Ok?**
No No
Replace indoor board. Replace indoor board.
Notes: Notes:
Before measuring the Volts DC on outdoor TB, Before measuring the Volts DC on outdoor TB,
disconnect the field wire on terminal 1. disconnect the field wire on terminal 1.
Before measuring the Volts DC on Indoor TB, Before measuring the Volts DC on Indoor TB,
disconnect the field wire on terminal 1.
Have the red probe of the meter on terminal 1
and the black probe on terminal 3. Reconnect
wiring when measurements are complete.
Recheck wiring and Recheck wiring and
connections connections
29
A08181