Table 3-7 Controller Pre-Trip Test Codes (Sheet 2 of 4)

 

 

Requirements: For units equipped with secondary supply probe only.

 

 

Pass/Fail Criteria: The temperature difference between primary and secondary probe

 

 

(supply) is compared.

P5-1

Supply Probe Test

NOTE

 

 

If this test fails, “P5-1” and FAIL will be displayed. If both Probe tests (this

 

 

and the SUPPLY/ RETURN TEST) pass, because of the multiple tests, the

 

 

display will read ’P 5’ ’PASS’.

 

 

 

 

 

Requirements: For units equipped with secondary return probe only.

 

 

Pass/Fail Criteria: The temperature difference between primary and secondary

 

 

probe (return) is compared.

 

 

NOTES

P5-2

Return Probe Test

1. If this test fails, “P5-2” and “FAIL” will be displayed. If both Probe tests

 

 

(this test and the SUPPLY/ RETURN) pass, because of the multiple

 

 

tests, the display will read “P 5,” “PASS.”

 

 

2. The results of Pre-Trip tests 5-0, 5-1 and 5-2 will be used to activate or

 

 

clear control probe alarms.

 

 

Setup: The system is operated through a sequence of events to test the compo-

 

Refrigerant Probes,

nents. The sequence is: Step 1, de-energize all outputs; Step 2, start unit with

P6

Compressor

unloader valve open. Open then close the suction modulation valve. Monitor

suction pressure; Step 3, open suction modulation valve to a known position;

and

 

Step 4, close suction modulation valve to a know position; Step 5, open econo-

 

Refrigeration valves

 

 

mizer valve; Step 6, close unloader valve; Step 7, open unloader valve; Step 8,

 

 

close economizer valve; Step 9, de-energize all outputs.

P6-0

Discharge

If alarm 64 is activated any time during the first 45 second period of Step 1, the

Thermistor Test

test fails.

 

P6-1

Suction

If alarm 69 is activated any time during the first 45 second period of Step 1, the

Thermistor Test

test fails.

 

P6-2

Discharge Pressure

If alarm 65 is activated any time during the first 45 second period of Step 1, the

Sensor Test

test fails.

 

P6-3

Suction Pressure

If alarm 66 is activated any time during the first 45 second period of Step 1, the

Sensor Test

test fails.

 

P6-4

Compressor Current

Compressor current is tested before and after start up. If current does not in-

Draw Test

crease, the test fails.

 

P6-5

Suction Modulation

Suction pressure is measured before and after the valve opens. If suction pres-

Valve Test

sure does not increase, the test fails.

 

P6-6

Economizer

Suction pressure is measured during Steps 4 and 5. If suction pressure does not

Valve Test

increase, the test fails.

 

P6-7

Unloader Valve Test

Suction pressure is measured during Steps 6 and 7. If suction pressure does not

 

 

increase, the test fails.

T-309

3-22

Page 47
Image 47
Carrier 69NT20-531-300 manual Supply is compared, Test fails, P6-2, Crease, the test fails, Increase, the test fails, P6-7

69NT20-531-300 specifications

The Carrier 69NT20-531-300 is a cutting-edge rooftop unit designed to meet the demanding requirements of commercial heating and cooling applications. This model embodies Carrier’s commitment to energy efficiency, reliability, and advanced technological features that enhance indoor comfort while minimizing operational costs.

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