Low Volt Controls, Cooling Only Units, Electric Heat

TROUBLESHOOTING PROCEDURE Continued

Low Volt Controls

Cooling Only Units:

Cooling only units require 18awg low Volt interconnecting wires between the indoor unit, outdoor units and thermostat. Ter- minals designated “Y1” (yellow) and “C” (brown) of the indoor air handler should be connected to the corresponding “Y” (yellow) and “C” (brown) wires or termi- nals of the outdoor condenser. Other wire(s) or terminals such as “R” (red) may not be needed and should be protect from making contact with the junction box or other metal surfaces.

Terminals “R”, “Y, “G”, “W” and “C” need to connect to the indoor, wall mounted thermostat.

NOTE: “W” is required for units with electric heat only “C” may not be needed on some thermostats.

Refer to low Volt interconnect diagram interconnect diagram ﬁgure 1 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 sup- ply can be measured by placing a meter across the “R” and “C” low Volt termi- nals of the air handler. The remote wall mounted thermostat will switch on and off the condenser through the yellow (Y) and black (Y1) wires. When the thermostat is calling for cooling, 24V can be measured between terminals (wires) Y and C.

The indoor unit contains an electronic anti short cycle timer feature (ASCT) that will prevent the outdoor condenser from short cycling. After the thermostat is satisﬁed there will be a three minute delay before the condenser is allowed to re-start.

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 heat- er assembly will interrupt power to the heater should an over-temperature condi- tion occur. Each electric heat assembly is also equipped with a one time fuse link. 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. If this oc- curs the limit switch assembly must be re- placed. Contact EMI technical service for a replacement.

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

5kw = 22.3 amps, 3kw = 13.5 amps, 1.5kw = 6.9 amps.

Units with Condensation Pumps: EMI CAC is equipped with an internal condensate pump capable of removing condensate up to a three foot vertical lift. Condensation generated by the evapo- rator will collect in the pumps’ reservoir. When the water level is high enough, a ﬂoat switch will close and energize the pump motor clearing the water from the reservoir. Should, for any reason, the wa- ter exceed the maximum preset level, a safety switch will open, there by interrupt- ing the (Y1) signal to the condenser. This will prevent the evaporator from generat- ing additional condensation and spilling out of the unit.

CAC Cassette Evaporator

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CAC specifications

EMI CAC, or Electromagnetic Interference Common-mode Current, is a critical concern in electronic device design and operation. It refers to the unwanted electromagnetic energy that can disrupt the normal functioning of electronic circuits, particularly in complex systems. EMI can arise from various sources, including power lines, radio frequency transmitters, and even other components within the same device.

One of the main features of EMI CAC is its dual nature. It can be both a source of interference and a metric to assess the integrity of electronic systems. The impacts of EMI are far-reaching, affecting communication signals, power supply reliability, and overall device performance. As technology progresses and devices become more compact, the likelihood of EMI issues increases, making it essential for engineers to develop effective solutions.

Several technologies are employed to mitigate EMI CAC in electronic systems. Shielding is one of the most common methods, involving the use of conductive materials to block electromagnetic fields. This can take the form of metal enclosures or coatings that prevent the escape of emissions. Another strategy involves the use of filters, such as ferrite beads and capacitors, which can suppress common-mode currents before they enter the sensitive parts of a circuit.

The characteristics of EMI CAC vary depending on several factors, including frequency, amplitude, and the specific environment in which the electronic devices operate. High-frequency EMI is particularly challenging due to its ability to penetrate enclosures and disrupt signals. Additionally, common-mode noise can often appear in differential signals, exacerbating the situation and making detection more difficult.

Achieving EMC (Electromagnetic Compatibility) is a major goal for designers dealing with EMI CAC. This involves not only reducing emissions from devices but also improving their immunity to external sources of interference. Effective grounding techniques and careful layout planning are crucial in minimizing EMI effects.

In summary, EMI CAC represents a significant challenge in modern electronics, with a need for advanced solutions to ensure device performance and reliability. By understanding its features, employing effective technologies for mitigation, and addressing its characteristics, engineers can create robust designs that thrive in the increasingly complex electromagnetic landscape of today’s technological world.