Diagnostics
112
RT-SVX34F-EN
G.
ODM 3 and/or 4 will not
cycle.
1.
OAS has failed.
1.
Perform OAS Resistance/Temperature check. Replace if necessary.
2.
ODM3 and/or 4 capacitor has failed.
2.
Check ODM capacitor, replace if necessary.
3.
Wiring, terminal, or CC2 contactor
failure.
3.
Check wires, terminals, and CC2. Repair or replace if necessary.
4.
ODM3 and/or 4 has failed.
4.
Check ODM, replace if necessary.
5.
RTRM is defective.
5.
Replace RTRM module
6.
ODF20 has failed.
6.
Check for proper voltage and contact closure. ODF20 relay has a 24
VAC holding coil. If voltage is present, replace relay.
H.
CPR2 and 3 (if applicable)
will not operate.
1.
No power to CC2 and/or 3 coil. Cool
Failure Possible.
1.
Check wiring, terminals and applicable controls (CCB2, CCB3, HPC2,
LPC2, WTL2, WTL3, TDL2 & TDL3)
2.
CC2 and/or 3 coil defective. Cool
Failure Indicated.
2.
Verify integrity of CC2 and/or 3 coil windings. If open or shorted
replace CC2 and/or CC3.
3.
CC2 and/or 3 contacts defective.
3.
If 24 VAC is present at CC2 and/or 3 coil, replace relay.
4.
RTRM is defective.
4.
24 VAC is not present at CC2 and/or 3 coil. Reset the Cool Failure by
cycling the service disconnect. Place the unit into Cool Stage 2 Mode, step
4 for constant Volume or step 6 for variable air volume, to insure CPR2
and 3 Compressor operation. Check input devices in #1 & #2 above, if
no controls have opened, and CC2 and/or 3 will not close, replace RTRM.
5.
DLT2 and DLT3 has tripped.
4.
Check for leaks, Open wire connections, Lose quick connect terminals,
TDL2 and TDL3 resistance check.
I.
Indoor motor (IDM) will not
operate
1.
IDM has failed.
1.
Check IDM, replace if necessary.
2.
Wiring, terminal, or contactor failure.
2.
Check wiring, terminals and F contactor. Repair or replace wiring,
terminals, or fan contactor F.
3.
ZSM is defective.
3.
Place unit in test mode. If the fan operates in the test mode, test the
ZSM using the appropriate test procedures.
4.
RTRM is defective.
4.
Check the RTRM fan output. Locate P2-1 on the RTRM. Measure
voltage to ground. If 24 VAC is not present on a call for fan, replace the
RTRM.
5.
Supply Fan Proving (FFS) switch has
opened.
5.
Check FFS and belts, repair or replace if necessary.
J.
No Heat (YC’s only) CFM will
not run, IP warms up, GV is
energized
1.
CFM has failed.
1.
Check CFM, replace if necessary.
2.
CFM capacitor has failed.
2.
Disconnect BROWN wires from capacitor, test, and replace if
necessary.
3.
Wiring, or terminal failure.
3.
Check wiring, and terminals. Repair, or replace if necessary.
4.
TNS3 and/or 4 has failed. (460/575 V
units only)
4.
Check for 230 VAC at TNS3 and/or 4 secondary, between Y1 and Y2.
If 230 VAC is not present, replace TNS3 and/or 4.
5.
Modulating gas is not configured
properly.
5.
Check RTOM wiring and control board software versions.
K.
No Heat (YC’s only) CFM
runs, GV energizes, IP does
not warm up.
1.
TNS3 and/or 4 has failed.
1.
Check for 115 VAC at TNS3 and/or 4 secondary, between X1 and X2.
If 115 VAC is not present, replace TNS3 and/or 4.
2.
Wiring or terminal failure.
2.
Check wiring and terminals. Repair or replace if necessary.
3.
IP has failed.
3.
With 115 VAC applied to IP, warm up should take place. Cold resistance
of IP should be a minimum of 50 Ohms. Nominal current should be 2.5
to 3.0 Amps.
L.
No Heat (YC’s only) GV does
not energize, CFM runs, IP
warms up
1.
Wiring or terminal failure.
1.
Verify presence of 24 VAC between IGN J1-7 terminal to ground, if not
present, check wiring and terminals. Repair or replace if necessary.
2.
GV has failed, in two stage units
2.
Measure voltage between TH and TR on the gas valve (GV). If 24 VAC
is present and the GV will not open, replace the GV.
3.
Pressure switch failure, in mod heat
units
3.
In mod heat units, verify the pressure switch is wired correctly. If wired
correctly, verify operation of pressure switch.
M.
Low Heat Capacity
Intermittent Heat. (YC’s only)
CFM runs in LO or HI speed
only, or; may not operate at all
in one speed or the other.
CFM has failed.
Check CFM, test LO and HI speed windings.
Table 83. Troubleshooting
SYMPTOM
PROBABLE CAUSE
RECOMMENDED ACTION