Hayward HeatPro HP50TA Troubleshooting Manual page 12

Common Error Codes
HP/HI on Display
HI
HP or HI is an indication the high pressure switch is open.
The switch opens when the refrigerant pressure rises above
HP
590PSI, and will automatically reset at 440PSI..
HeatPro Display
Troubleshooting HP/HI
The most common cause of HP or HI error code is restricted water flow. An open bypass valve that
allows the heat exchanger to be pressurized, but does not allow flow through it is a likely culprit.
When heating a spa, there may not be sufficient flow through the system for proper operation at higher
Summit Display
water temperatures. All heat pumps require a minimum of 30 gpm water flow, but at higher water
temperatures a higher flow rate of at least 40 gpm may be required.
Other causes of HP/HI error code
Heat Pump runs for a few seconds then fails on HP/HI error
Thermostatic Expansion Valve (TXV) failure. Loss of charge in the power head of the TXV closes the
valve and will result in a HP or HI error code. To determine if this is the problem, observe both high and
low pressure readings when heat pump is running. If TXV is bad high pressure will quickly rise to
590PSI, while at the same time the low pressure will quickly drop.
Refrigerant Overcharge Overcharge of the heat pump is unlikely, but not impossible. Heat pumps do not
leave our factory overcharged, so the only way it can occur is if service has been previously performed
on the system and the technician overcharged the refrigerant after or during a repair. To determine if this
is the issue recover all refrigerant from the system, pull a 500 micron vacuum, and then recharge to
factory charge (on data plate).
Heat Pump does not run- HP/HI on display
HP Switch
Bad HP switch. Since the HP switch is an automatic reset, and the pressures within the refrigeration
Note black wires.
system will equalize shortly after the heat pump cuts off, HP or HI on the display without the heat pump
HP switch common to all
running will not be related to the refrigerant pressure check the continuity of HP switch. Switch should be
R-410A heat pumps
closed. If open replace switch. The HP switch is a screw on style and does not require removing
refrigerant charge to change. Be sure to use a thread sealant when installing new switch. Always use a
back up wrench when installing new pressure switch.
If switch is closed, but HP/HI is displayed check wires to switch for breaks.
If no breaks are found replace control board.