Refrigerant Charge Auto-Test; Sensors); Minimum Load Valve Auto-Component Test; Supply Fan Auto-Component Test - Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting

XA1S Running
XA2S Running
XB1S Running
XB2S Running
The EXV auto-component test functions by staging compres-
sor A1, B1, and B2 for a 75-ton unit and A1, A2, B1, B2 for
other units, and verifying
± AC_SH_DB (auto-component test superheat deadband) of
the superheat set point (SH.SP).
The auto-component test superheat deadband (AC_SH_DB)
will default to 2°F with a range of 0°F to 10°F.
Setting EX.TR=ON will perform the following:
1. Stage compressors A1/B1/B2 for 75-ton unit, A1/A2/B1/
B2 for other units.
2. Allow compressors to run for 5 minutes.
3. Verify that SH.A1, SH.A2, SH.B1, and SH.B2 have stabi-
lized to SH.SP ± AC_SH_DB. If all 4 superheats are
SH.SP ± AC_SH_DB then set PASS status and end test.
4. If any superheat is outside SH.SP ± AC_SH_DB, allow
compressors to run for 5 more minutes.
5. Set PASS/FAIL status according to whether each super-
heat has stabilized to SH.SP ± AC_SH_DB and end test.
If SH.SP ± AC_SH_DB then XA1S, XA2S, XB1S, and
XB2S=PASS, otherwise
XB2S=FAIL.
If the EXV superheat is not within SH.SP ± SH.DB, the super-
heat alert will be logged:
T064 EXV A1 Superheat Outside Range
T065 EXV A2 Superheat Outside Range
T066 EXV B1 Superheat Outside Range
T067 EXV B2 Superheat Outside Range
Refrigerant Charge Auto-Test (without Liquid

Sensors)

The refrigerant charge auto test without liquid sensors requires
the following conditions:
1. Unit is not shut down due to failure (A152).
2. OAT>70°F.
3. No compressors are on or requested on.
4. All compressors are available for staging.
The test screen will display the following:
CD.TR ON
Running Test Status and Timer
CD.ET
SCT.A 105.3 F
50.4 F
SST.A
OAT 66.3 F
SCT.B 106.5 F
SST.B 49.8 F
When no liquid sensors are installed, all compressors and outdoor
fans of both Circuit A and B are commanded to be ON. The oper-
ator will read OAT, SCT.A, and SST.A in order to then compare
the values to the A charging chart to determine if refrigerant in
Circuit A is properly charged. The operator reads OAT, SCT.B,
and SST.B, in order to then compare the values to the B charging
chart to determine if refrigerant in Circuit B is properly charged.
Thus this is a semi-auto test because operator intervention is re-
quired to determine the test results. No test results are displayed.
Setting CD.TR=ON will perform the following:
1. Command supply fan ON.
2. Command all A and B Circuit outdoor fans ON.
3. Stage all A and B Circuit compressors ON.
EXV A1 Auto-Test Status
EXV A2 Auto-Test Status
EXV B1 Auto-Test Status
EXV B2 Auto-Test Status
the superheat is
XA1S, XA2S, XB1S,
Run Chrg Test without Lqd Sen
Cir A Sat. Condensing Temp
Cir A Sat. Suction Temp
Outside Air Temp
Cir A Sat. Condensing Temp
Cir A Sat. Suction Temp
4. Let compressors run 5 minutes.
5. Prompt user to read charging charts.
6. Let compressors run 5 minutes.
7. End test.

Minimum Load Valve Auto-Component Test

Minimum load valve (MLV) is also referred to as hot gas by-
pass valve (HGBV).
within
The hot gas bypass auto-component test requires the following
conditions:
1. Unit is not shut down due to failure (A152).
2. MLV=ENBL.
3. No compressors are on or requested on.
4. Compressor A1 is available to start.
The test screen will display the following:
ML.TR No
ML.TD Running 1/1 Test Status and Timer
MLV
DP.A
ML.ST Running
The MLV auto-component test functions by comparing the dis-
charge pressure when MLV is closed to that when MLV is
open, and verifying DP.A decreases by at least AC_MLVDR.
and
The auto-component MLV deadband (AC_MLVDR) will de-
fault to 5 psig with a range of 0 to 10 psig.
Setting ML.TR=ON will perform the following:
1. Command A1 ON and MLV OFF.
2. Let circuit stabilize for 5 minutes and save DP.A (recorded).
3. Command MLV ON.
4. Let circuit stabilize for 5 minutes and record DP.A (current).
5. Verify DP.A (recorded) - DP.A (current) > AC_MLVDR.
6. End test.
If DP.A (recorded) – DP.A (current) > AC_MLVDR then
ML.ST=PASS, otherwise ML.ST=FAIL.

Supply Fan Auto-Component Test

The supply fan auto-component test requires the following
conditions:
1. Unit is not shut down due to failure (A152).
2. Supply fan VFD not in bypass mode.
3. Power exhaust or return fan (if enabled) not in bypass mode.
4. Supply fan not on.
The test screen will display this:
SF.TR
SF.DT
S.VFD
S.PWR 0.00 kW
SP
SF.ST
The supply fan auto-component test functions by commanding the
supply fan to minimum speed (STATPMIN), and verifying that
VFD power (S.PWR) and duct static pressure (SP) is increasing.
Setting SF.TR=ON will perform the following:
1. Record S.PWR and SP.
2. Command S.VFD to STATPMIN, and let run 5 minutes.
3. Verify S.PWR increases.
4. If SP.CF=ENBL and SP.S=ENBL, verify SP increases.
5. End test.
36
Run MLV/HGBV Auto-Test
Off Minimum Load Valve Relay
331.3 psig Cir A Discharge Pressure
MLV/HGBP AutoTest Result
ON Run Supply Fan Auto-Test
Running Test Status and Timer
0% VFD1 Actual Speed %
VFD1 Actual Motor Power
0.00˝ H20 Static Pressure
Pass SF Auto-Test Result