Equipment Operation Problems - Carrier 33CS Installation, Service, And Troubleshooting Instructions

Equipment Operation Problems —
tem thermostat is designed to energize constant volume heat-
ing and cooling equipment to satisfy the system comfort
requirements.
When the TEMP system thermostat fails to pick a system
mode, or fails to energize the heating or cooling equipment
when expected, the problem usually involves the config-
urable options of the TEMP system thermostat.
If the TEMP system thermostat selects a system mode,
but the heating or cooling equipment fails to energize, the
problem may be with the relay pack.
TEMP SYSTEM THERMOSTAT FAILS TO SELECT SYS-
TEM MODE — When the TEMP system thermostat fails to
select a system mode, check the items that influence the TEMP
system thermostat to select system mode.
1. The zone must be 1.5° F or more from set point.
2. The TEMP system thermostat system switches (FAN, COOL,
HEAT) must be set to AUTO or ON to operate.
3. Ensure that the TEMP system thermostat Heating and Cool-
ing Time Guard has had time to expire. If the Time Guard
Between Modes option (category 4, option 2) has been
configured ON, the system will not operate until time guard
has expired. Time guard delay occurs after power up, re-
set, or system mode has been released. Length of the time
guard is (2.6 seconds x TEMP system thermostat device
address) + 5 minutes.
If the Time Guard Between Modes option is configured
OFF, the length of the time guard is approximately
1.5 minutes.
The Time Guard Override option may be used to over-
ride the time guard to 30 seconds for one cycle. To ac-
tivate the override, toggle category 4, option 3, ON and
then OFF.
4. Check the configuration of the TEMP system thermostat
System Heating Mode Lockout, Heating Lockout Tem-
perature Set Point, and Cooling Lockout Temperature Set
Point options. Based on the outside-air temperature, the
TEMP system thermostat can lock out either system cool-
ing or heating modes.
TEMP SYSTEM THERMOSTAT FAILS TO ENERGIZE
SECOND STAGE — When the TEMP system thermostat
fails to energize the second stage of the heating or cooling
equipment, check the items that affect the decision of the
TEMP system thermostat to energize the second stage of heat-
ing or cooling.
1. When a system mode is selected and the reference zone
demand is equal to or greater than 8° F, the TEMP system
thermostat Energy Saver Lockout function automatically
disables the second stage operation of the unit for ap-
proximately 20 minutes. This function saves energy by
allowing the first stage of the heating or cooling unit to
satisfy the system load at times of low thermal load (morn-
ing cool down or warm up).
2. When the TEMP system thermostat Comfort Trend Stag-
The TEMP sys-
3. Check the TEMP system thermostat display for a flash-
ANNUNCIATOR DISPLAYED BUT EQUIPMENT NOT
ENERGIZED — The TEMP system thermostat HEAT or
COOL annunciator is ON, but the heating or cooling equip-
ment is not energized.
Check the TEMP system thermostat Auxiliary Relay op-
tion (category 4, option 9). If the TEMP system thermostat
is configured to operate an economizer, the TEMP system
thermostat will enable the economizer for first stage cooling
when the outside air temperature is less than 64.9 F.
Check the LEDs on the relay pack controlled by the TEMP
system thermostat. Perform the correct procedure.
LED Not Lit– The TEMP system thermostat HEAT or COOL
annunciator is ON but the LED on the relay pack is not lit.
With the relay pack plugged in, check the voltages across
the relay pack input connector plug. Voltages should read
approximately 4 to 6 vdc (steady) between the black wire
and the appropriate relay pack input wire. If not, replace re-
lay pack.
LED Is Lit– The TEMP system thermostat HEAT annuncia-
tor is ON, the LED on the relay pack is lit, but the corre-
sponding equipment stage is not energized.
1. Check the AC voltage across the relay board common (red)
2. Check the AC voltage across the relay board common (red)
3. Check the AC voltage across a suspected contactor coil.
4. Other possibilities are: bad contactor, defective equip-
31
ing function (category 7, options 4 and 5) is configured
to a value other than zero, the TEMP system thermostat
will energize the second stage of heating or cooling only
after it determines that the reference zone demand is not
being met by the first stage of heating or cooling.
If the Comfort Trend Staging function is configured off,
the TEMP system thermostat will energize the second stage
3 minutes after the first stage, if the demand of the ref-
erence zone is equal to or greater than 2° F.
ing HEAT or COOL annunciator. A blinking annunciator
indicates a supply-air temperature problem.
and any deenergized relay (H1 or C1). The voltage should
read 24 vac. If not, check for wiring error.
and any indicated energized relay board output (FAN).
The voltage should read near zero (<1 vac). If 24 vac is
read, check for bad relay board.
The voltage should read 24 vac. If not, check the con-
tactor coil wiring.
ment, or no unit power.