Resetting Cooling And Ignition Lockouts; Unit Economizer Control (Eca) Test Procedures - American Standard YSC036A Installation, Operation And Maintenance Manual

Trouble Shooting
Heating Failure
Verify Heat Failure by Ignition
Module (IGN) LED indicator:
OFF: No Power or Failure
ON: Normal
Slow Flash: Normal, Heat Call
Fast Flash:Error Code:
1 Flash:No Communication
2 Flashes:System Lockout
3 Flashes:Pressure Switch Fail
4 FlashesTC01 or TC02 Open
5 Flashes:Flame w/o Gas Valve
6 Flashes:Flame Rollout Open
Cooling Failure
1. Cooling and heating set point
(slide pot) on the thermostat has
failed.
2. CC1 or CC2 24 VAC control circuit
has opened, check CC1 & CC2
coils, and any of the controls
below that apply to the unit
(HPC1, HPC2, LPC1, LPC2,
Frostat™).
Resetting Cooling and
Ignition Lockouts
Cooling Failures and Ignition
Lockouts are reset in an identical
manner. Method 1 explains resetting
the system from the space; Method 2
explains resetting the system at the
unit.
Method 1
To reset the system from the space,
turn the "Mode" selection switch at
the thermostat to the "Off" position.
After approximately 30 seconds, turn
the "Mode" selection switch to the
desired mode, i.e. Heat, Cool or Auto.
Method 2
To reset the system at the unit, cycle
the unit power by turning the
disconnect switch "Off" and then
"On" .
RT-SVX21F-EN
Unit Economizer Control
(ECA) Test Procedures
Electro Mechanical Control
This series of tests will allow you to
diagnose, and determine where, and
if a problem exists in the system
economizer operation. Test 1
determines if the problem is in the
Unit, or if it is in the ECA. Test 2 tests
sensor inputs. Test 3 tests the
resistors and sensors. Conduct the
tests in numerical order until
problem is found.
Test 1
Verifying that the economizer
actuator (ECA) is functional:
1. Using the "Test Mode" described
in the "System Start-Up"
section, put the unit into the
economizer mode and verify that
the economizer actuator (ECA)
drives fully open (approximately
90 seconds).
2. If the ECA is not driving the
dampers, verify that 24 VAC is
between the ECA terminals TR
and TR1 is present. If 24 volts is
not present, a wiring or terminal
problem exists from the control
transformer. Make any necessary
repairs, see wiring diagrams to
troubleshoot.
3. If 24 VAC is present, adjust the
minimum position
potentiometer fully clockwise. If
the actuator does not drive, the
economizer actuator is bad.
Replace the ECA.
Test 2
Testing the ECA resistors and
sensors
1. Testing the Mixed Air Sensor
(MAS). Disconnect the wires
connected to T and T1 on the
ECA, and;
a. Measure the resistance of the
sensor between the wires
180B and 181B.
b. Measure the temperature at
the MAS location. Using the
Temperature versus
Resistance chart, verify the
accuracy of the MAS.
Replace the sensor if it is out of
range.
2. Testing the Outdoor Air Switch. If
the temperature is above 60
degrees, it will need to be chilled.
Measure the resistance of the
sensor on the ECA SO and +.
The resistance should be
approximately 390 Ohms.
Replace the Switch if it is open.
Replace the ECA if it is out of
range.
3. Testing the R1 Resistance.
Measure the resistance of the
sensor on the ECA SR and +.
The resistance should be
approximately 420 Ohms.
Replace the ECA if it is out of
range.
4. Testing the R2 Resistance.
Measure the resistance of the
sensor on the ECA P and P1.
The resistance should be
approximately 130 Ohms.
Replace the ECA if it is out of
range.
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