Page 38
CBX40UHV
IX− FLOW CHARTS
1. Air Handler Control (AHC) Checkout
Power−up − Unit Size Code (Number or letter) displayed represents air handler model size and
capacity. If three horizontal bars displays, Air Handler Control (AHC) does not recognize unit
size code (air handler model size and capacity).
AHC recognizes
Unit Size Code?
Electric heat
Installed?
Finished
Which Heat
Mode?
Refer to EvenHeater Operation flow diagram, Air
Handler or ECB40 Electric Heat installation
instructions.
W1 Call?
YesNo
Yes
No (Display
Alarm Code
302)
Standard
EvenHeater
Refer to Heat Pump or
Cooling Sequence of
Operation flow diagrams, Air
Handler or ECB40 Electric
Heat installation instructions.
A call for electric heating first, second or third
stage is initiated when 24 VAC (R) is detected on
W1, W2 and W3 inputs on AHC. (Factory mounted
metal jumpers connect W1/2 and W2/W3.)
At the completion of each heat element demand
(W1, W2, and W3), the control board will
immediately de−energize the corresponding pilot
relay(s).
At the completion of all heating demands, the
indoor blower will run for an additional 10
seconds before de−energizing.
No
Yes
NOTE − If the call for lower heat element is
removed, AHC will automatically de−energize
higher heat elements.
Indoor blower will immediately start to delivery
CFM as set by heating mode jumper on board
with activation of first electric heat pilot relay.
22 VDC pilot relays on board are energized one
at a time. There is a minimum of 10 seconds
delay between pilot relay activations.
After all electric heat installations, AHC must be
manually configured to detect number of heat
elements. Refer to Configuring/Detecting
electric heat elements flow diagram, Air Handler
or ECB40 Electric Heat installation
IMPORTANT: Field replacement controls may need to be
manually configured to validate air handler unit size code.
Refer to Configuring Unit Size Codes flow diagram, Air Handler
or ECB40 Electric Heat installation instructions.
ONE (H1)
H1
TWO (H1−H2)
H1
H2
H2
THREE (H1−H3)
H1
H2
H3
FOUR (H1−H4)
H1 AND H2
H3
H4
FIVE (H1−H5)
H1 AND H2
H3 AND H4
H5
T−STAT CALL
W1
W2
W2
NUMBER OF HEAT ELEMENTS DETECTED
NOTE − AHC will not recognize higher heat
elements calls if lower heat element is not present.
−
−
−
RECOMMEND − USE FIGURE 11 AS A REFERENCE
FOR SETTING JUMPER CONFIGURATIONS ON THE
AIR HANDLER CONTROL.
Figure 33. Air Handler Control Checkout
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