Please use this site to assist you in troubleshooting most geothermal heatpumps.

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Please use this site to assist you in troubleshooting most geothermal heatpumps.

These guide lines should help;
Although please note that I am not responsable for any damage to any equipment that you work on following these guide lines.

If operational difficulties are encountered, perform the preliminary checks below before referring to the troubleshooting charts.
Because some controls are mounted internally and high voltage connections are exposed if the cabinet is opened, only a qualified technician should access them.
I'll be constantly working on this site so check back.

General

* Check the air filter.
* Check the water supply.
* Verify that the unit is receiving electrical supply power.
* Verify that there is pressure in the loop.
* Verify that the loop pumps are running.

After completing the preliminary checks described above,
inspect for other obvious problems such as leaking connections,
broken or disconnected wires, etc.

Field Inputs

Be certain that the thermostat is set higher than the actual room temperature and the selector switch to heat if in heating mode, or that the thermostat is set lower than room temperature and the selector switch is on cool if air conditioning is desired. If the thermostat is programmable, make sure it has fresh batteries.
All inputs are 24VAC from the thermostat and can be verified using a volt meter between C and Y, G, O, W.
24VAC will be present at the terminal.

For example,
between Y and C if the thermostat is sending an input to the compressor;
between G and C if the thermostat is sending an input to the blower;
between O and C if the thermostat is sending an input to the reversing valve for cooling;
between W and C if the thermostat is sending an input to the auxillery or emergency heat (heat strip);

Outputs

The compressor relay input is 24VAC and can be verified using a voltmeter.
The fan signal is usually passed to an external fan relay and the input is 24VAC and can be verified using a voltmeter.

Performance Troubleshooting
Performance Troubleshooting Htg Clg Possible Cause Solution
Insufficient capacity X X Dirty Filter Replace or clean
Not cooling or heating properly X Reduced or no Air flow in heating Check for dirty air filter and clean or replace Check fan motor operation and airflow restrictions Too high of external static. Check static vs blower table
X Reduced or no Air flow in cooling Check for dirty air filter and clean or replace Check fan motor operation and airflow restrictions Too high of external static. Check static vs blower table
X X Leaky duct work Check supply and return air temperatures at the unit and at distant duct registers if significantly different, duct leaks are present
Unit Doesn't Operate in Cooling X X Low refrigerant charge Check superheat and subcooling per chart
X X Restricted metering device Check superheat and subcooling per chart. Replace.
X Defective Reversing Valve Perform RV touch test
X X Thermostat improperly located Check location and for air drafts behind stat
X X Unit undersized Recheck loads & sizing check sensible clg load and heat pump capacity
X X Scaling in water heat exchanger Perform Scaling check and clean if necessary
X X Inlet Water too Hot or Cold Check load, loop sizing, loop backfill, ground moisture.
High Head Pressure X Reduced or no Air flow in heating Check for dirty air filter and clean or replace Check fan motor operation and airflow restrictions Too high of external static. Check static vs blower table
X Reduced or no water flow in cooling Check pump operation or valve operation/setting Check water flow adjust to proper flow rate
X Inlet Water too Hot Check load, loop sizing, loop backfill, ground moisture.
X Air Temperature out of range in heating Bring return air temp within design parameters
X Scaling in water heat exchanger Perform Scaling check and clean if necessary
X X Unit Overcharged Check superheat and subcooling. Re weigh in charge
X X Non-condensables in system Vacuum system Reweigh in charge
X X Restricted metering device Low Suction Pressure Check superheat and subcooling per chart. Replace.
Low suction pressure X Reduced water flow in heating Check pump operation or water valve operation/setting Plugged strainer or filter. Clean or replace. Check water flow adjust to proper flow rate
X Water Temperature out of range Bring water temp within design parameters
X Reduced Air flow in cooling Check for dirty air filter and clean or replace Check fan motor operation and airflow restrictions Too high of external static. Check static vs blower table
X Air Temperature out of range Too much cold vent air? Bring entering air temp within design parameters
X X Insufficient charge Check for refrigerant leaks
Low discharge air
temperature in heating X Too high of air flow Check fan motor speed selection and airflow chart
X Poor Performance See 'Insufficient Capacity'
High humidity X Too high of air flow Check fan motor speed selection and airflow chart
X Unit oversized Recheck loads & sizing
check sensible clg load and heat pump capacity





Functional Troubleshooting
Functional Troubleshooting Htg Clg Possible Cause Solution
Only Compressor Runs X X Thermostat wiring Check G wiring at heat pump. Jumper G and R for fan operation.
X X Fan motor relay Jumper G and R for fan operation. Check for Line voltage across BR contacts. Check fan power enable relay operation (if present)
X X Fan motor Check for line voltage at motor. Check capacitor
X X Thermostat wiring Check thermostat wiring at heat pump. Jumper Y and R for compressor operation in test mode.
Unit Doesn't Operate in Cooling X Reversing Valve Set for cooling demand and check 24VAC on RV coil. If RV is stuck, run high pressure up by reducing water flow and while operating engage and disengage RV coil voltage to push valve.
X Thermostat setup Check for 'O' RV setup not 'B'
X Thermostat wiring Check O wiring at heat pump. Jumper O and R for RV coil 'Click'.
X Thermostat wiring Put thermostat in cooling mode. Check for 24VAC on O (check between C and O); check for 24VAC on W (check between W and C). There should be voltage on O, but not on W. If voltage is present on W, thermostat may be bad or wired incorrectly.

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