Carrier PSD006-070 High Head Pressure, Low Suction Pressure, Low Discharge Air, High Humidity

Table 39 — WSHP Troubleshooting (cont)

	FAULT	HEATING	COOLING	POSSIBLE CAUSE	SOLUTION
High Head Pressure		X		Reduced or no airflow in	Check for dirty air filter and clean or replace.
				heating	Check fan motor operation and airflow restrictions.
					External static too high. Check blower performance per
					Tables 11-13.
			X	Reduced or no water flow in cool-	Check pump operation or valve operation/setting.
				ing	Check water flow adjust to proper flow rate. See Tables 19 and 31.
			X	Inlet water too hot	Check load, loop sizing, loop backfill, ground moisture.
		X		Air temperature out of range in	Bring return-air temperature within design parameters.
				heating
			X	Scaling in water heat exchanger	Perform condenser cleaning.
		X	X	Unit overcharged	Check superheat and subcooling. Reweigh in charge.
		X	X	Noncondensables in system	Remove refrigerant, evacuate system and charge unit.
		X	X	Restricted metering device	Check superheat and subcooling per Tables 20-30. Replace.
Low Suction Pressure		X		Reduced water flow in	Check pump operation or water valve operation/setting.
				heating	Plugged strainer or filter. Clean or replace.
					Check water flow adjust to proper flow rate.
		X		Water temperature out of range	Bring water temperature within design parameters.
			X	Reduced airflow in cooling	Check for dirty air filter and clean or replace.
					Check fan motor operation and airflow restrictions.
					External static too high. Check blower performance per
					Tables 11-13.
			X	Air temperature out of range	Too much cold vent air. Bring entering air temperature within design
					parameters.
		X	X	Insufficient charge	Check for refrigerant leaks.
Low Discharge Air		X		Too high airflow	Check blower performance per Tables 11-13.
Temperature in Heating		X		Poor performance	See “Insufficient Capacity.”
High Humidity			X	Too high airflow	Check blower performance per Tables 11-13.
			X	Unit oversized	Recheck loads and sizing check sensible cooling load and heat pump
					capacity.
Low Refrigerant Suction		X		Normal operation	Check/compare with Tables 20-30.
Pressure
		X		Reduced water flow	Check pump operation.
					Check strainer or filter.
					Improper flow regulator. Replace flow regulator.
		X		Water temperature out of range	Bring water temperature within proper range.
		X		Scaling in water to refrigerant	Conduct water quality analysis.
				heat exchanger
			X	Reduced airflow	Check for dirty air filter.
					Check for dirty air coil.
					Check fan motor operation.
					External static pressure exceeds fan operating parameters.
		X	X	Return air temperature below	Space temperature too cold. Increase space temperature.
				minimum
					Excessive fresh air. Reduce amount of fresh air exposure.
			X	Supply air bypassing to return	Check for leaking ductwork.
				airstream (zone systems)
		X	X	Insufficient refrigerant charge	Locate and repair leak.
		X	X	Improperly located TXV sens-	Locate bulb on suction line between reversing valve and compressor.
				ing bulb
		X	X	Failed or restricted metering	Failed TXV power head, capillary or sensing bulb. Replace.
				device
					Plugged TXV strainer. Unplug TXV strainer.
High Refrigerant		X	X	Insufficient refrigerant charge	Locate and repair leak.
Superheat
		X	X	Improperly located TXV sens-	Locate bulb on suction line between reversing valve and compressor.
				ing bulb
		X	X	Failed or restricted metering	Failed TXV power head, capillary or sensing bulb. Replace.
				device
					Plugged TXV strainer. Unplug TXV strainer.
High Refrigerant		X	X	Excessive refrigerant charge	Remove refrigerant as needed.
Subcooling
		X	X	Failed or restricted metering	Failed TXV power head, capillary or sensing bulb. Replace.
				device
					Plugged TXV strainer. Unplug TXV strainer.
TXV and/or Low Pressure		X		Normal operation	May occur when entering water temperature is close to minimum.
Tubing Frosting
		X	X	Insufficient refrigerant charge	Locate and repair leak.
		X	X	Failed or restricted metering	Failed TXV power head, capillary or sensing bulb. Replace.
				device	Plugged TXV strainer. Unplug TXV strainer.
Equalizer Line		X	X	Failed or restricted metering	Failed TXV power head, capillary or sensing bulb. Replace.
Condensing or Frosting				device
					Plugged TXV strainer. Unplug TXV strainer.
	LEGEND
LED	— Light-Emitting Diode
RV	— Reversing Valve
TXV	— Thermostatic Expansion Valve

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