1 air conditioning pressure switches. 2 high pressure switch used to protect the compressor when...
TRANSCRIPT
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High Pressure switchHigh Pressure switch
• Used to protect the compressor
• When condensing temp gets too high
• Reads High Side Pressure
• Located in condensing unit
• Can be wired line duty or control voltage
• Used to protect the compressor
• When condensing temp gets too high
• Reads High Side Pressure
• Located in condensing unit
• Can be wired line duty or control voltage
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High Pressure switch cont…High Pressure switch cont…
• Opens on rise in pressure/ closes on drop
• Adjustable type-normally set to open at 350 psi with a 75 differential
• Non-adjustable type-are pre-set to pressures-re-set button must be pushed
• Opens on rise in pressure/ closes on drop
• Adjustable type-normally set to open at 350 psi with a 75 differential
• Non-adjustable type-are pre-set to pressures-re-set button must be pushed
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Low pressure SwitchLow pressure Switch
• Safety switch• Opens on pressure drop/ Closes
on pressure rise • Condensing unit de-energized• Indoor Blower motor remains
running
• Safety switch• Opens on pressure drop/ Closes
on pressure rise • Condensing unit de-energized• Indoor Blower motor remains
running
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Low pressure Switch cont…Low pressure Switch cont…
• opens at about 55 psig (R-22)• located in condensing unit• wired line duty or control voltage
• opens at about 55 psig (R-22)• located in condensing unit• wired line duty or control voltage
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Low pressure Switch cont…Low pressure Switch cont…
Opens due to: • Restricted air flow- registers,
return grills, loose belt, dirty evaporator
• Low refrigerant charge- leaks
Opens due to: • Restricted air flow- registers,
return grills, loose belt, dirty evaporator
• Low refrigerant charge- leaks
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Low Ambient ControlLow Ambient Control
• Cycles condenser fan On and Off
• Runs system at Design pressure -when outside ambient temp.
are low-found in some residential
units-usually found in commercial
systems
• Cycles condenser fan On and Off
• Runs system at Design pressure -when outside ambient temp.
are low-found in some residential
units-usually found in commercial
systems
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Low Ambient Control cont…Low Ambient Control cont…
• Wired in line side only-best to wire after “C” on
condenser fan
• Closes on pressure rise (250 psig)• Opens on pressure drop (200 psig)
-50 psig differential
• Wired in line side only-best to wire after “C” on
condenser fan
• Closes on pressure rise (250 psig)• Opens on pressure drop (200 psig)
-50 psig differential
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Low Ambient Control cont…Low Ambient Control cont…
There are different types of LAC’s:
•pressure sensing•condenser discharge air
sensing•liquid line sensor
There are different types of LAC’s:
•pressure sensing•condenser discharge air
sensing•liquid line sensor
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Low Ambient Control cont…Low Ambient Control cont…
Function LAC provides:
•High condensing pressure•Good refrigerant flow•Keeping low side temp above
freezing
Function LAC provides:
•High condensing pressure•Good refrigerant flow•Keeping low side temp above
freezing
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Sail SwitchSail Switch
• Mechanical switch that proves air flow• Located in ductwork• Switch is open when no airflow is
present• Will close when fan comes on• Prevents freezing of evaporator coil
due if indoor airflow is not established.
• Wired in “Y” circuit
• Mechanical switch that proves air flow• Located in ductwork• Switch is open when no airflow is
present• Will close when fan comes on• Prevents freezing of evaporator coil
due if indoor airflow is not established.
• Wired in “Y” circuit