Carrier 38AUZ User Manual download pdf (Page 19)

SERVICE

Comfort Alert Diagnostic Module

The Comfort Alert Diagnostic Module (CADM) monitors and

analyzes data from the Copeland Scroll

three-phase compres-

sor and the thermostat demand. The CADM also provides a

3-minute anti-recycle time delay to compressor cycling.

The CADM detects causes for electrical and system related

failures without any sensors. Flashing LEDs communicate the

Alert codes to guide service technicians in accurately and

quickly troubleshooting the system and determining root cause

for the failure.

Inputs to the CADM include 24-vac power, thermostat Y1,

compressor contactor coil (common side) and compressor

power leads (from the compressor contactor).

Control of the compressor contactor coil is through a

normally-closed (power on the module) contact between

terminals P and C.

Communications of status and alert conditions is through three

LEDs located on the top edge of the module housing (see Fig.

21): POWER (green), ALERT (yellow), and TRIP (red).

The POWER LED indicates the presence of control power to

the CADM.

Fig. 21 — CADM Housing/LED Locations

The ALERT LED indicates an abnormal condition exists in the

system through a flash code. The ALERT LED will blink a

number of times consecutively, pause and the repeat the

process. The number of blinks, defined in Table 6, correlates to

a particular abnormal condition; troubleshooting tips are

provided for each Alert code. Reset of the ALERT may be

automatic or manual. If the fault condition causing the Alert is

self-corrected, the Alert code will be removed and the CADM

will automatically reset and allow the system to restart

normally. Manual reset requires that main power to the 38AU

unit be recycled after the cause for the Alert condition has been

detected and corrected.

The TRIP LED indicates either a time-delay period is currently

active (RED LED is blinking) or the module has locked out the

compressor (RED LED is on steady). A lockout condition will

occur when the CADM detects a thermostat demand at input Y

but there is no power at the compressor line terminals T1 or T2

or T3. This lockout can occur due to a safety switch (LPS or

HPS) opening and de-energizing the compressor contactor, the

compressor-motor internal overload opens, or other internal

power interruption has occurred. Reset of the TRIP LED

requires that unit main power be recycled after the loss of

power to the compressor condition has been detected and

corrected.

Simultaneous Blinking of YELLOW and RED LEDs indicates

control power input to the CADM is low. Check control circuit

transformer and wiring.

Troubleshooting the CADM Wiring – Flashing LEDs also

indicate wiring problems to the CADM. See Table 7 for

discussion of additional LED flash codes and troubleshooting

instructions.

Input Terminal Voltage

Control

Power

R 24-V

Control

Common

C 24-V

Cooling Y 24-V

Contactor

Coil

P 24-V

Line A T1 Line

Line B T2 Line

Line C T3 Line

POWER

(GRN)

ALERT

(YEL)

TRIP

(RED)

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 27 28

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Carrier 38AUZ User Manual Page 19

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