Controls User Manual
– HPAH
Rev_20200811 Page 7 of 9
No Display – If pushing one of the four front buttons does not refresh the display, there may
be no power to the air handler, or the transformer has failed or the controller has failed.
Thermostat calls – The status screen (default) will show heating, cooling or continuous fan
calls detected from the thermostat (Table 1). Using the outer keys, the user can scroll
through the screens to see individual thermostat calls and fan speed (Table 3).
If a thermostat is calling but not detected by the control
1. Check the thermostat and its connections
2. Check thermostat wiring at the thermostat and air handler.
3. Check the 8gang relay indicator lights.
W1, W2, Y1, Y2,O and G1 are connected
directly from the thermostat terminal strip.
The 8 gang relay converts 24vac thermostat
signals to digital signals for input to the iStat6
controller. If the lights are on but the
controller does not respond, the problem is
the wiring to the control or the control has
failed.
No Auxiliary Heating – Try Test Mode first – pushing the
button on the bottom (underneath) of the control will run the
auxiliary pump and fan for 20 seconds. Pipes should get warm and fan should run. No pump
– check the pump relay for a 24vac signal from the control, wiring and pump.
No HP Cooling/Heating - Check for 24vac at the terminal strip Y1-OUT. If not, check wiring
to and from control and control.
No Blower - The fan can be tested from 0-100% by placing the primary thermostat in FAN
ON (or jumper R to G) with no heat or cool call. Then, adjust ContFan up and down within
ADMIN mode. It should modulate smoothly from 1% to 100% and off completely at 0%. If it
fails to run, check wiring from controller to motor speed control, motor speed control, wiring to
motor and motor.
Blower motor never fully stops, even with no demand signal
Ensure control displays NO CALL. If not, check thermostat settings and
thermostat wiring.
Too much airflow, causing noise
This can occur due to undersized ductwork, dirty filter or improper setup of the air
handler heating/cooling loads. Check airflow % settings. Installing a 2-stage heat
pump will reduce the airflow most of the time (first stage).
