Emerson 2 User Manual

Control connections to the InteleCool2 unit use customary HVAC terminal designations R, G, W & Y. 

Contact closures between the 24 VAC (R) and different control connections supply control voltage to 

the electric panel components responsible for the desired function. Operating modes are controlled by 

contact closures as follows:

Wall-mounted thermostats are to be low voltage, snap action or mercury type. Un-manned sites should 

use a HEAT/COOL/AUTO type subbase to provide automatic switchover during climate changes.

The high pressure switch is mounted in the liquid line. Electrically, it is connected in series with the 

compressor start circuit, which will shut down the compressor and condenser fan if the liquid pres-

sure exceeds 400 PSIG (2758 kPa). This protects the InteleCool2 in the event of condenser motor fail-

ure or condenser coil blockage.
The pressure switch is an auto reset device. When the system pressure drops below 300 PSIG 

(2069 kPa), the switch will reset. (An optional lockout relay is available which allows the switch to be 

used as a manual reset safety.) If the call for cooling is present, the compressor start circuit will be 

energized and the compressor will start after the 3 minute anti-short cycle time.

Please review the following table for the recommended control options based on the site ambient and 

your need for year-round operation.

Low Pressure Switch—The low pressure switch is mounted in the compressor suction line. Electri-

cally, it is connected in series with the compressor start circuit, which will shut down the compressor 

and condenser fan if the suction pressure drops below 35 PSIG (241 kPa). The switch will automati-

cally reset once the system pressure rises above its cut-in setting (60 psig, ±5 psig [414 kPa, ±34 kPa]). 

This protects the InteleCool2 in the event the evaporator fan fails, the filter becomes clogged or there 

is a loss of refrigerant. If the call for cooling is present, the compressor will start after the 3 minute 

anti-short cycle time.
Low Pressure Bypass Timer—A low ambient temperature start relay is included with the low 

pressure option. This relay locks out (ignores) the low pressure switch on start-up until the system 

pressure stabilizes. This bypass relay is adjustable and should be set for 3 minutes greater than the 

anti-short cycle timer setting. This option can be used for applications down to 50°F (10°C). For con-

trol down to -20°F (-28.9°C), use the T-pack1 and T-pack2 options, which include fan cycle control.

R

24 VAC

G

Evaporator Fan

W

Heating

Y

Cooling (compressorized or Economizer)

General

Standard

None

50°F (10°C)

115°F (46.1°C)

General

Standard

Low pressure with low pressure bypass 

timer

50°F (10°C)

115°F (46.1°C)

General

Standard T-pack1 or T-pack2

-20°F (-28.9°C) 115°F (46.1°C)

Telecom/365-day operation Standard T-pack1 or T-pack2

-20°F (-28.9°C) 115°F (46.1°C)

General

Standard High ambient

50°F (10°C)

125°F (51.7°C)

General

Standard High ambient, low pressure with low 

pressure bypass timer

50°F (10°C)

125°F (51.7°C)

Telecom/365-day operation Standard High ambient with T-pack1 or T-pack2

-20°F (-28.9°C) 125°F (51.7°C)