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