Carrier 25VNA Service Manual page 18

FLASH CODE
OPERATION
(Amber LED)
System Malfunction
25VNA EVENT / FAULT (CONT.)
Heat or Cool
Mode
Outside Normal Operating Range
(e.g. improper load calculation, sys-
tem match issue, outside cooling
range, outside heating range etc)
loose High Pressure Switch harness
leads
Pressure Switch disconnected from
ODU Control Board
Both
Faulty Pressure Switch
Restriction due to debris leading to
Overcharge when charging in Cool-
ing mode
Restriction in EXV plus Long Line
Application leading to Overcharge
when charging in Cooling mode
None condensible leading to high
load
Service Valve left closed (Liquid or
Vapor)
Overcharged System
Outdoor Airflow too low or off
Cool
Restriction in Filter Drier plus Long
Line Application and filter drier on
84
Outdoor Unit
Restriction in EXV plus Overcharge
Restriction in Circuits or Tubing
Electric Heater plus Heat pump ap-
plication: Electric Heater stuck on
Furnace plus Heat pump applica-
tion: Furnace stuck on
Restriction in Filter Drier plus Long
Line Application and filter drier on
Indoor Unit
Expansion Orifice Restriction
Service Valve left closed (Vapor
Service Valve)
Heat
Indoor Airflow too low or off
Overcharged System
Reversing Valve Stuck in Cooling
Restriction due to debris
Possible Causes
Consult Application Guidelines
Check HPS harness
Check HPS connection on ODU control
Check Discharge pressure with gauge, if
less than 610 +/ --- 20 psig and switch is
open (measure resistance) then replace
pressure switch
Clean System (refer to application
guideline) and replace filter drier
If long line, troubleshoot EXV
Clean System (refer to application
guideline) and replace filter drier
Ensure Service Valves are open
Check system charge using Cooling
Charging Mode (follow proper charging
procedures)
Check Outdoor Coil for clogging (ice or
debris) and clean or de ---ice if neces-
sary; Troubleshoot Outdoor fan motor
and make sure it is working; follow Out-
door Airflow troubleshooting instruction
Clean System (refer to application
guideline) and replace filter drier
troubleshoot EXV
Check kinks and straighten or replace
circuits
If User Interface is not requesting Electric
Heat check for heater relays, if on
troubleshoot Electric Heater
If not in Defrost and Furnace is running
same time as heat pump, troubleshoot
Furnace
Clean System (refer to application
guideline) and replace filter drier
Troubleshoot TXV (see guide below)
Troubleshoot EXV (see guide below)
Ensure Vapor Service Valve is open
Check Indoor for clogging (ice or debris)
and clean or de ---ice if necessary;
Troubleshoot Indoor fan motor and
make sure it is working; follow Indoor
Airflow troubleshooting instruction
Check charge in cooling (if in Cooling
Charge Mode Ambient Range), if low
add charge using Charging Mode (follow
proper charging procedures); if out side
cooling charge mode range, pull out
charge, weigh in using heating charge
mode
troubleshoot reversing valve
Clean System (refer to application
guideline) and replace filter drier
18
ACTION