Low Ambient Control; Anti-Short Cycle Protection; Fan Delays; Nuisance Trip Protection And Three Strikes - York ZT SERIES Technical Manual

5167821-YTG-K-1118

Low ambient control

An integrated low-ambient control allows units to operate in the cooling mode down to 0°F outdoor ambient without additional
components or intervention. Optionally, the control board can be programmed to lockout the compressors when the outdoor air
temperature is low or when free cooling is available.

Anti-short cycle protection

To aid compressor life, an anti- short cycle delay is incorporated into the standard control. Compressor reliability is further
ensured by programmable minimum run times. For testing, the anti-short cycle delay can be temporarily overridden with the
push of a button.

Fan delays

Fan on and fan off delays are fully programmable. Furthermore, the heating and cooling fan delay times are independent of
one another. All units are programmed with default values based upon their configuration of cooling and/or heating capacity.

Nuisance trip protection and three strikes

To prevent nuisance calls, the control board uses a three times, you're out philosophy. The high, low-pressure switch, anti-
freeze protection, low voltage or heating high limit must trip three times within two hours before the unit control board locks out
the associated compressor.An alarm message is then displayed on the LCD screen.
Low limit control
The low limit control (LLC) prevents the supply air from dropping below a specified set point, when there is a demand for
cooling during cold outside conditions. This is a programmable setpoint.
Reliability
From the beginning, all units undergo computer automated testing before they leave the factory. Units are tested for refrigerant
charge and pressure, unit amperage, and 100% functionality. For the long term: all units are painted with a long lasting,
powder paint that stands up over the life of the unit. The paint used has been proven by a 750-hour salt spray test.
Full perimeter base rails
The permanently attached base rails provide a solid foundation for the entire unit and protect the unit during shipment. The
rails offer rigging holes so that an overhead crane can be used to place the units on a roof.
Easy installation
Gas and electric utility knockouts are supplied in the unit underside as well as the side of the unit. Utility connections can be
made quickly and with a minimum amount of field labor. All units are shipped with 2-inch throw-away filters installed.
Wide range of indoor airflows
All supply air blowers are equipped with a belt drive that can be adjusted to meet the exact requirements of the job. A high
static drive option is available for applications with a higher CFM and/or static pressure requirement.
Standard factory warranty
All models include a 1-year limited warranty on the complete unit. Compressors and electric heater elements each carry a 5-
year warranty. Aluminized steel (10 year) and stainless steel tubular heat exchangers carry a 15-year warranty.
8 Johnson Controls Ducted Systems