EMI S1C, WLHA manual Low volt controls, Cooling Only Units, Electric Heat

Troubleshooting procedure Continued

! CAUTION !

While in test mode, all timers are eliminated. Avoid short cycling the compressor. After system checks are complete, the control must be re- turned to normal operation. DO NOT

LEAVE THE SYSTEM IN TEST MODE!

Low volt controls

Cooling Only Units

Cooling only units utilize low volt interconnecting wires between the indoor unit, outdoor units and thermostat. For air handlers with unit mounted controls, wires (WLCA/WLHA) designated “Y” (yellow) and “C” (brown) of the indoor air handler should be connected to the corresponding “Y” (yellow) and “C” (brown) wires or terminals of the outdoor condenser. Other wires or terminals such as “R”(red) or “O” (orange) may not be needed and should be protect by a wire nut from making contact with the junction box or other metal surfaces.

Refer to low volt interconnect diagram interconnect diagram figure 1 for unit mounted controls and figure 2 for remote thermostat connection.

A 24V transformer located in the indoor air handler unit provides low volt control power to both the indoor air handler and outdoor condenser. The 24v power supply can be measured by placing a meter across the “R” and “C” low volt terminals of the air handler. The air handler will switch on and off the condenser through the yellow

(Y)wire. When the air handler is calling for cooling, 24V can be measured between terminals (wires) Y and C.

Electric Heat

Units with electric heat utilize a control relay located on the circuit board in the control box. As a safety feature, an auto resetting limit switch located on the heater

end plate or on the heater assembly will interrupt power to the heater should an over-heat condition occur. Each electric heat assembly is also equipped with a one time fuse link (if trigered a new fuse link is required). Should electric heat temperatures rise above the auto resetting limit switch, a non-resetting, one time fuse link will open and the heater will remain off.

The following current values apply when the unit is connected to a 230V power supply. These values include fan motor cur- rent. If the supply power is different, this will in turn affect the amp draw of the heater.

5kw = 22.3 amps, 4kw = 18 amps,

3kw = 13.5 amps.

Optional Heat pump

with Electric Heat

Heat pump units with electric heat utilize four to six interconnecting, low volt wires depending control setup and/or thermostat selected. Refer to the low volt interconnect section and figures 1 & 2 for your particular unit. a 24V transformer located in the indoor air handler provides low volt control power to both the air handler and condenser. With high volt power supplied to the condenser, 24v can be measured across the red (R) and brown (C) wires at all times.

Cooling: The air handler will cycle the condenser on and off through the yellow (Y) wire. To check for a condenser signal, select cooling mode on the indoor unit or thermostat and place the set-point temperature below room temperature. Then, with a voltmeter check for 24 volts across the yellow (Y) and brown (C) wires. If no signal is found then re-check all wiring connections to ensure that they match the low Volt interconnect diagram. Check the output of the 24v transformer (located in the air handler) to ensure that the control voltage is present.

WLCA/WLHA High Wall Evaporator 31 www.enviromaster.com