System Types

  • Gas, oil, or electric heat with air conditioning
  • Warm air, hot water, high efficiency furnaces, heat pumps, steam, gravity.

Must be installed by a trained, experienced technician

Read these instructions carefully. Failure to follow these instructions can damage the product or cause a hazardous condition.

 CAUTION: ELECTRICAL HAZARD. Can cause electrical shock or equipment damage. Disconnect power before beginning installation.

 MERCURY NOTICE: If this product is replacing a control that contains mercury in a sealed tube, do not place the old control in the trash. Contact your local waste management authority for instructions regarding recycling and proper disposal.


  1. Remove cover from Equipment Interface Module (EIM).
  2. EIM can be mounted on equipment or on wall. Use included wall anchors for mounting onto drywall (drill 3/16″ holes for drywall; 7/32″ holes for plaster).

 CAUTION: This product may be damaged if mounted inside HVAC equipment. Install only on the outside of HVAC equipment.


Connect wires as shown below (see wiring guides on following pages)

Connect wires

Restore power and check LED:

  • LED blinks rapidly: Normal information transfer.
  • LED blinks once: Incoming message to EIM.
  • LED blinks continuously: Wiring problem.
    Check wiring to terminals 1, 2, 3.
  • LED always off: Wiring problem. Check wiring to terminals 1, 2, 3.
  • LED always on: EIM may need replacement

 NOTE: It is normal for the LED to blink continuously during startup, and while checking equipment status (Auto Discover mode).

Wiring guide

  • Typical hookup of conventional system with up to three-stage heat and two-stage cool with one transformer (3H/2C, 2H/2C, 2H/1C, 1H/2C, 1H/1C, 1H, 2H, 3H, 1C, 2C conventional).
    Wiring guide
  • Typical hookup of heat pump system with up to four-stage heat and two-stage cool with one transformer (4H/2C, 3H/2C, 2H/2C, 2H/1C, 1H/1C heat pump systems).
    Wiring guide

Wiring guide—equipment

With power supply

  • Typical hookup of powered humidifier.
    Typical hookup of powered humidifier
  • Typical hookup of powered ventilation.
    With power supply
  • Typical hookup of powered dehumidifier (whole house dehumidifier).
    With power supply

Without power supply

  • Typical hookup of non-powered humidifier.Typical hookup of non-powered humidifier
  • Typical hookup of non-powered ventilation.
    Without power supply
  • Typical hookup of variable speed blower for dehumidification in low speed.
    Without power supply




Temperature Ranges

  • Heat: 40° to 90°F (4.5° to 32°C)
  • Cool: 50° to 99°F (10° to 37°C)

Operating Ambient Temperature

  • -30° to 150°F (-34 to 66°C)

Shipping Temperature

  • -30° to 150°F (-34 to 66°C)

Operating Relative Humidity

  • 5% to 90% (non-condensing)

Physical Dimensions

  •  7-9/16″ H x 4-35/64″ W x 1-21/64″ D 185 mm H x 116 mm W x 34 mm D

Electrical Ratings

TerminalVoltage (50/60Hz)Running Current
W Heating20-30 Vac0.02-1.0 A
W2 Heating20-30 Vac0.02-1.0 A
W3 Heating20-30 Vac0.02-1.0 A
Y Cooling20-30 Vac0.02-1.0 A
Y2 Cooling20-30 Vac0.02-1.0 A
Aux Auxiliary Heat20-30 Vac0.02-1.0 A
Aux2 Auxiliary Heat20-30 Vac0.02-1.0 A
G Fan20-30 Vac0.02-1.0 A
O/B Changeover20-30 Vac0.02-1.0 A

Documents / Resources

Honeywell TH9000 Series Equipment Interface Module [pdf] Installation Guide
TH9000 Series, Equipment Interface Module, 69-2406EFS

Leave a comment

Your email address will not be published.