User Manual for Emerson 1F75P-21PR PTAC Thermostat

Quick Guide

The Emerson 1F75P-21PR is a programmable PTAC thermostat designed for single-stage cooling and one or two-stage heating systems. It features a configurable installer menu for system settings, a jumper wire for converting between PTHP and PTAC modes, and a battery backup for clock retention during power outages.

Installation and Wiring

Before installation, ensure the electrical power to the system is disconnected at the main fuse or circuit breaker box. All wiring must conform to local and national electrical codes.

• Terminal Designations:
  • GL: Low Speed Fan Relay
  • R: Power (24V)
  • O/B: Changeover Terminal (Energized in Cool for O, Heat for B)
  • Y: Heat and Cool Mode 1st Stage Compressor
  • GH: High Speed Fan Relay
  • W: Heat Mode – 2nd Stage Heat (Electric)
  • C: Common wire for 24V

System Conversion: To convert the system from PTHP to PTAC, cut the jumper wire located on the back of the thermostat and change menu item #20 from HP to AC.

Installer Menu

To access the Installer Menu, set the system switch to the OFF position, then press and hold the temperature Up and Down buttons simultaneously for 3 seconds. Use the Up/Down buttons to navigate and change settings. Press the RUN/HOLD button to exit.

• Item 20: Algorithm (AC or HP)
• Item 30: Heat Cycle Rate (SLO, MEd, FAS)
• Item 32: Aux Cycle Rate (Available if HP is selected)
• Item 35: Cool Cycle Rate
• Item 50: Compressor Lockout (Protects from short cycling)
• Item 65/66: Maximum Heat/Minimum Cool Limits
• Item 74: Schedule Type (7-Day, 5-1-1 Day, or Non-Programmable)
• Item 83: Continuous Display Light (Requires C wire)

Operation and Programming

The thermostat supports a 7-day programmable schedule. To set the current time and day, press the SET TIME button and use the Up/Down arrows to adjust. To enter a heating or cooling program, move the system switch to the desired mode (Heat or Cool), press the PROGRAM button, and follow the on-screen prompts to set times and temperatures for each period (Wake, Leave, Return, Sleep).

Troubleshooting

If the thermostat is not functioning correctly, check the following:

• No Heat/Cool/Fan: Check for a blown fuse or tripped circuit breaker, ensure the furnace power switch is ON, and verify the furnace blower compartment door is properly installed.
• No First Stage Heat: Verify the system switch is set to Heat, check wiring connections, and ensure menu item 20 and the jumper wire configuration match.
• Call for Service Icon: This indicates the system cannot reach the setpoint within 2 hours or there is a compressor issue.

Technical Specifications

• Electrical Rating: 20 to 30 VAC, NEC Class II, 50/60 Hz
• Terminal Load: 1.5 A per terminal, 2.5A maximum all terminals combined
• Setpoint Range: 60° to 85° F (16° to 29° C)
• Operating Ambient: 32°F to +105°F (0° to +41°C)
• Operating Humidity: 90% non-condensing maximum