Heatcraft Beacon walk-in Error Codes
Applies to: Beacon II Walk-In Systems. Compiled and paraphrased from Heatcraft Refrigeration Products' own Beacon II Refrigeration Systems Installation and Operation Manual, H-IM-79G, June 2020, part 25001401, published on heatcraftrpd.com. Temperatures, pressures and resistances are Heatcraft's published figures. Table last updated Aug 13, 2026.
How to read the codes
This is the controller inside the walk-in system rather than the box itself, so it applies whatever name is on your cooler: Heatcraft supplies Bohn, Larkin, Climate Control and Chandler, and Beacon II boards sit in walk-ins built by many box makers. A three-digit red LED on the board shows three different kinds of thing and they are easy to confuse. MODE words like Coo, dEF, Pdn and SEr are NORMAL OPERATION. A-codes are alarms. E-codes are errors. Note also that the alarm relay is a plain dry contact: Heatcraft states it DOES NOT INDICATE WHAT CAUSED THE ALARM, so a bell or light tells you something is wrong and nothing more, and somebody has to read the board.
The codes
| Code | Meaning | Likely causes | Operator-safe steps | Technician work |
|---|---|---|---|---|
| Coo, dEF, Pdn, oFF, drn, dLY, tSt, SEr | NOT FAULTS. These are the eight normal operating modes | Coo is cooling, dEF defrost, Pdn pumpdown, oFF satisfied and off, drn draining, dLY delay, tSt test mode, SEr service mode | Worth learning before anything else, because these are what the board shows almost all the time. SEr means somebody has left the system in service mode, which is a common reason a walk-in is not cooling and no fault is showing | SEr persists until the service switch is returned or CLEAR is pressed. Only the Master board matters on multi-evaporator systems |
| A1 | High box temperature alarm | Room temperature exceeded the programmed alarm high value for the programmed alarm time, which defaults to 60 minutes | The alarm you actually care about. Defaults are 50F on an air defrost cooler and 5F on an electric defrost freezer. It clears itself once the box comes back down, so a cleared alarm does NOT mean nothing happened; check product temperatures anyway | Alarm high ALH and alarm time ALt are programmable. Does not apply during defrost |
| A2 | Low box temperature alarm | Room temperature dropped below the programmed alarm low value for the alarm time | Freezing product in a cooler is as expensive as spoiling it. Defaults are 30F air defrost, -15F electric | Clears automatically when temperature returns above setpoint |
| A3 | System start-up failure: the compressor tried four times and failed | Compressor will not start, pumping down and retrying every four minutes | The system is still trying. This does not clear itself: Heatcraft says it clears only by putting the system in SERVICE MODE or removing power, which means somebody has to attend | Compressor internal overloads, contactor coil voltage, contactor pulled in |
| A4 | Input fault: box temperature, suction temperature or pressure transducer open or not installed | A failed or disconnected sensor or transducer | Clears only when the failed part is replaced | Replacing the room sensor, suction sensor or pressure transducer clears A4 |
| E1, E2, E3 | Sensor shorted, open or not installed: room, defrost and suction respectively | Failed sensor or a broken connection at the board | On E1 and E3 the system will pump down, cycle off and NOT restart until the fault is fixed or the breaker is reset. That is a walk-in that stays off, so treat it as urgent | Do not remove sensors from evaporators to check them. Compare the board reading against a thermometer at the same point, or test in stirred ice water: at 32F expect 32,650 ohms, and replace if it is off by about 1,000 |
| E4 | Suction pressure transducer shorted, open or not installed | Failed transducer, damaged harness, or a transducer damaged by over-pressure | System will not restart until it is fixed | Heatcraft warns not to leak test above 150 PSI with the transducer connected, because that damages it. If testing higher, disconnect it first |
| E5 | Outdoor temperature sensor shorted | Failed sensor on the condensing unit or its wiring | Less urgent than the others | Check sensor, wiring and board connection. Replace or remove |
| E6 | Low superheat during cooling, held at 0F for two minutes | Wrong refrigerant type programmed, an iced coil, an expansion valve not closing, a compressor not running, or a bad suction sensor or transducer | IMPORTANT AT START-UP: Heatcraft states that on initial start-up the system may cycle off at two minutes on low superheat and restart itself, possibly several times, and that you should NOT shut the system off while it does. The valve is finding its setting. On an established system it is a fault | Check programmed refrigerant against actual first, then coil for ice, then EEV step position, then closure by pumpdown test |
| E7 | Compressor shutdown on a safety: high pressure, low pressure or oil pressure | Heatcraft's guide branches into four full checklists. Low pressure covers charge, EEV stuck, iced coil, nozzle selection, clogged EEV inlet screen and line sizing. High pressure covers overcharge, non-condensables, condenser fan failure and a DIRTY CONDENSER COIL. Oil pressure covers oil level, sump screen and pump | On the high pressure side, a dirty condenser coil is on the manufacturer's own list and is the one an operator can prevent entirely | Work Heatcraft's branch for the specific safety that tripped rather than guessing. Also check the LPS time delay relay is set to 1 minute |
| E9 | Multi-in to multi-out communication wiring error between evaporator boards | Crossed or broken communication wiring in the daisy chain. Out must go to In, never Out to Out | Usually appears after work has been done on the system rather than out of nowhere | Heatcraft gives a table showing WHICH BOARDS DISPLAY E9 FOR EACH BROKEN LINK, so the pattern of which boards report the error locates the break. Only appears after a connection has previously succeeded |
| 888 on the display | Supply voltage has fallen below 18 VAC | Transformer tapped for the wrong voltage, field wiring break or short, or a grounding problem | No operator action | Heatcraft flags a specific and common installation error: on 208 to 240V systems the multi-tap transformer ships wired for 240V, and MUST be moved to the 208V tap on EVERY evaporator if the supply is 208V |
| Loc | Not a fault. The board is locked and settings cannot be changed | Somebody locked it deliberately to stop unauthorised changes | Nothing wrong with the system | Press PROGRAM REVIEW, hold MONITOR, press ENTER to toggle. UnL confirms unlocked |
If this needs a walk-in system technician
3 companies in this directory name Heatcraft on their own site: that page shows who has been phone-confirmed, who publishes 24/7 cover, and what each puts in writing. Start there if the brand matters more than the city.
Two questions worth reading before you ring anyone: what to do first when a code appears and how to tell whether it is yours to fix.
Heatcraft also runs a technical support line for its own equipment. The number, and what they will and will not do for you, is worth reading before you ring: most will help a technician who is already on site and will not talk an operator through a repair.
Or browse walk-in systems service companies by state:
Indiana: Evansville · Fort Wayne · Indianapolis · South Bend
Kentucky: Lexington · Louisville · Owensboro
Ohio: Akron · Canton · Cincinnati · Cleveland · Columbus · Dayton · Sandusky · Toledo · Upper Sandusky · Youngstown
Pennsylvania: Allentown · Altoona · Erie · Harrisburg · Lancaster · Pittsburgh · Scranton · Williamsport
West Virginia: Charleston · Clarksburg · Huntington · Martinsburg · Morgantown · Parkersburg · Wheeling
Related: the PM checklist that prevents the most common codes outright, and the operator guides for symptom-first diagnosis.
Not sure this is the right make? The lookup by code shows every make that uses a given code, and flags the ones that mean different things depending on the machine in front of you.