SEQUENCE OF OPERATION
COOLING – Circuit
COMPRESSOR CONTROL MODULE
The compressor control module is standard on all models covered by this manual. The compressor control module is an
Adjustable Delay On Make And Break Timer
On initial power up or anytime power is interrupted to the unit, the delay on make period begins, which will be 2 minutes plus 10% of the delay on break setting. When the delay on make is complete and the high pressure switch and low pressure switch is closed, the compressor contactor is energized. Upon shutdown, the delay on break timer starts and prevents restart until the delay on break and delay on make periods have expired.
During routine operation of the unit with no power interruptions, the compressor will operate on demand with no delay.
High Pressure Switch and Lockout Sequence
If the high pressure switch opens, the compressor contactor will
Low Pressure Switch, Bypass, and Lockout Sequence
If the low pressure switch opens for more than 120 seconds, the compressor contactor will
Alarm Relay Output
Alarm terminal is output connection for applications where alarm relay is employed. This terminal is powered whenever the compressor is locked out due to HPC or LPC sequences as described.
NOTE: Both high and low pressure switch controls are inherently automatic reset devices. The high pressure switch and low pressure switch cut out and cut in settings are fixed by specific air conditioner unit model. The lockout features, both soft and manual, are a function of the Compressor Control Module.
ADJUSTMENTS
Adjustable Delay on Make and Delay on Break Timer
The potentiometer is used to select Delay on Break time from 30 seconds to 5 minutes. Delay on Make (DOM) timing on
0.5 minute (30 seconds) | DOB = 123 | second DOM |
1.0 minute (60 seconds) | DOB = 126 | second DOM |
2.0minute (120 seconds) DOB = 132 second DOM
3.0minute (180 seconds) DOB = 138 second DOM
4.0minute (240 seconds) DOB = 144 second DOM
5.0minute (300 seconds) DOB = 150 second DOM
During routine operation of the unit with no power interruptions the compressor will operate on demand with no delay.
Typical Settings for Dual Unit Installation:
Unit 1: DOB set at 2 minutes, and DOM is 132 seconds
Unit 2: DOB set at 4 minutes, and DOM is 144 seconds
PRESSURE SERVICE PORTS
High and low pressure service ports are installed on all units so that the system operating pressures can be observed. A pressure table can be found later in the manual covering all models. It is imperative to match the correct pressure table to the unit by model number. See Table 2.
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