Tempstar Heat Pump error codes & fault diagnosis in Greater Vancouver
The call usually comes in the same way. It is February, the house is sitting three degrees below setpoint, and there is a small red light blinking behind the louvred panel of the outdoor unit. Sometimes the homeowner has already counted the flashes. Sometimes they have already found a chart online that does not match their unit at all.
That last part matters more than people expect. Tempstar heat pumps have gone through several generations of control boards, and the flash pattern that means one thing on a mid-2000s board can mean something completely different on a recent communicating model. There is no universal Tempstar code chart. The authoritative source is the legend printed on the label inside your own cabinet, or the installation manual for your specific model number.
So this page does not hand you a list of numbers. It gives you the categories those codes fall into, the order a technician works through them, and an honest line between what you can check standing in your own backyard and what needs a licensed tech with gauges and a meter. HeatLand has been servicing heat pumps across the Lower Mainland since 1999, and the same faults come up over and over in this climate for reasons that have a lot to do with where we live.
Where the code actually lives on a Tempstar heat pump
Start by finding the display, because there are three different places it might be. On most Tempstar outdoor units there is a control board behind a service panel on the side of the cabinet, with one or two small LEDs — amber, red, or green — that blink in a repeating pattern. Older boards use a simple count: pause, three flashes, pause, three flashes. Newer boards use a two-digit pattern, a slow group followed by a fast group, which you read as a number like 3-4.
If your system uses a communicating or Observer-style wall control, the fault will show as text or a numeric code on the thermostat screen instead, and there is usually a fault history menu that stores the last several events with timestamps. That history is genuinely useful — a fault that has repeated eleven times in three days tells a very different story than a one-off.
Some installs also put a board in the indoor air handler or furnace that flashes its own separate code. Two boards, two codes, two different meanings.
Write down what you see before you touch anything: the LED colour, the exact flash count and rhythm, which unit it is on, and the model and serial number from the rating plate. Cutting power clears the code on many boards and you lose the evidence. Photograph the label with the code legend on it while the panel is open.
Defrost and outdoor temperature sensor faults — the Lower Mainland’s most common category
This is the one we see most, and the reason is our weather. Metro Vancouver spends most of the winter between roughly zero and eight degrees with high humidity, which is precisely the band where a heat pump’s outdoor coil frosts fastest. A unit in Calgary sees dry cold. A unit in Burnaby or Langley sees wet cold, and it runs defrost cycles constantly.
Defrost is controlled by a sensor clipped to the outdoor coil tubing, plus an ambient sensor reading outdoor air. Both are thermistors — they change electrical resistance with temperature. When one drifts out of range, comes loose from the tube, or corrodes at the connector, the board sees a value it does not believe and posts a sensor fault. Symptoms: the outdoor unit turns into a block of ice, or it defrosts constantly and never delivers heat, or auxiliary heat runs endlessly and your hydro bill jumps.
A technician checks the sensor’s resistance against the manufacturer’s temperature-resistance table, confirms the clip is tight on the tubing and not just dangling in air, and inspects the connector for green corrosion — which is common on units within a few kilometres of the water in Richmond, Tsawwassen, White Rock or the North Shore, where salt air eats terminals.
What you can do: clear snow, leaves and cedar debris from around the unit and make sure the drain area under it is not frozen solid. A unit sitting in a puddle of ice cannot defrost properly.
Pressure faults: high-pressure and low-pressure lockouts
Pressure switch faults are the board telling you the refrigerant circuit is operating outside safe limits, and it shut the compressor down to protect it. Do not reset these repeatedly. Each forced restart into a genuine pressure fault is hard on the compressor, and a compressor is the single most expensive component in the system.
High-pressure faults in heating mode usually point indoors: a filter so loaded it is collapsing inward, a blocked return, a blower running at the wrong speed, closed supply registers in half the house, or a dirty indoor coil. The refrigerant cannot dump its heat, so pressure climbs. In cooling mode, a high-pressure fault more often points outdoors — a coil packed with cottonwood fluff, which is a real seasonal problem here in June, or an outdoor fan that has stopped.
Low-pressure faults mean the suction side is starved. That is a restricted airflow across the outdoor coil in heating, an outdoor fan failure, a plugged metering device, or the one nobody wants to hear: the charge is low because there is a leak. Heat pumps are sealed systems. They do not consume refrigerant. Losing charge means it went somewhere, and topping it up without finding the leak is money poured into the air.
A tech puts gauges on, reads superheat and subcooling, checks the switch continuity, and separates a genuine pressure problem from a failed switch.
Thermostat, low-voltage and communication faults
A surprising share of heat pump no-heat calls never involve the refrigerant circuit at all. The 24-volt control side is where a lot of intermittent faults hide.
Communicating Tempstar systems run a data link between the wall control, the indoor unit and the outdoor unit. If that link drops, you get a communication fault and the system either falls back to a limited emergency mode or shuts down entirely. Causes we find in the field: a control wire nicked by a staple during a renovation, a splice in an attic or crawlspace that has corroded in our damp air, thermostat wire run alongside line-voltage cable picking up interference, or a low-voltage transformer that has failed after a nearby surge.
On conventional systems, the equivalent symptoms are subtler. A miswired heat pump — O/B reversing valve terminal set for the wrong logic, or W2 and auxiliary staging wired backwards — will heat when it should cool, or run electric backup while the compressor sits idle. That is not a code fault, it is a configuration fault, and it often traces back to a thermostat swap done by a previous owner or a well-meaning DIYer.
You can safely check that the thermostat has power, that its batteries are fresh if it uses them, and that the system switch is on HEAT rather than EM HEAT. Everything past the thermostat plate belongs to a technician.
Compressor, outdoor fan and motor-related faults
When the board reports a compressor or motor fault, it is generally reporting one of four things: the motor drew too much current, it drew too little, it did not start, or the winding overheated.
A locked-rotor or failed-start fault on a single-stage Tempstar usually leads a technician straight to the start components and the contactor. Contactors here take a beating — the contacts pit, and on coastal installs the whole assembly can corrode. A pitted contactor makes intermittent contact, the compressor tries to start on partial voltage, and you get a fault that clears itself and comes back next week. On variable-speed and two-stage models, the drive or inverter board reports its own set of faults and the diagnostic path is different again; those boards have their own LED legends.
Outdoor fan faults show up as overheating and high-pressure trips in cooling, or as poor heating output. The failure is often mechanical before it is electrical: a bearing dries out, the blade clips the shroud, or the motor mount has rusted through. We see rusted fan mounts constantly on units more than a decade old near the water.
Safety line: the outdoor unit contains capacitors that hold a dangerous charge after power is cut. Do not open the electrical compartment. This is a licensed-technician job, full stop.
Reversing valve and “blowing cold in heat mode” complaints
This one produces the most confused phone calls, and it does not always throw a code at all. The reversing valve is what lets a heat pump run backwards — it redirects refrigerant so the outdoor coil absorbs heat instead of rejecting it. When it fails to shift, or shifts only partway, the system runs in the wrong mode. Your thermostat calls for heat and the vents blow cool air.
Before assuming a valve failure, a technician rules out the simple explanations, because most of the time it is not the valve. Is the system in a defrost cycle right now? During defrost a heat pump deliberately runs in cooling mode for a few minutes to melt the outdoor coil, and the supply air goes cool. That is normal. Is the thermostat’s O/B setting configured for the right logic? Is the outdoor unit even running, or is electric backup carrying the whole load — which feels like weak heat because backup strips warm the air less aggressively than people expect?
Only after those are eliminated does the valve itself come into question: is the solenoid coil getting voltage, does it click when energized, is the valve body stuck. A stuck valve sometimes frees with a controlled tap while energized, sometimes it needs replacement, which is a refrigerant recovery and brazing job — TSBC-certified work, not a homeowner repair.
How a HeatLand technician sequences the diagnosis
Order matters, because checking things in the wrong sequence wastes an hour and sometimes destroys the evidence. Here is roughly how it goes on a Lower Mainland heat pump call.
First, talk to you. What changed, when did it start, is it constant or intermittent, was anything worked on recently. Renovation timelines explain an enormous number of control-wiring faults.
Second, read the code without resetting it, and pull the fault history if the wall control stores one. Repeat patterns and timestamps narrow things faster than any single reading.
Third, verify the basics before reaching for gauges: filter condition, return and supply airflow, registers open, outdoor unit clear of debris and not iced, breakers on, disconnect closed, thermostat mode and setting correct. A meaningful share of calls end here.
Fourth, electrical. Confirm 24-volt supply, check the transformer, inspect the contactor and low-voltage connections, look for corrosion at every terminal — especially on coastal installs.
Fifth, sensors and switches. Verify thermistor resistance against the manufacturer’s table, check pressure switch continuity, confirm the defrost sensor is physically clipped where it belongs.
Only then does the refrigerant circuit come into it. Gauges last, because a pressure reading interpreted without knowing the airflow is a pressure reading interpreted wrong.
We explain what we found and what it means before doing any work, and you get a written no-obligation estimate.
What drives the cost of a Tempstar heat pump repair — and how to avoid the next one
Nobody can quote a heat pump repair over the phone honestly, and you should be cautious of anyone who tries. What we can tell you is what moves the number: whether the failed part is a sensor, a control board, a motor or the compressor; whether the system holds a full charge or has a leak that must be located and repaired; whether the model is a conventional single-stage or a communicating variable-speed unit with proprietary boards; how accessible the equipment is, because a rooftop or crawlspace install takes longer than a side-yard pad; and whether refrigerant recovery, brazing and a permit are involved. Age matters too — at some point repeated repairs on an aging unit stop making sense against replacement, and we will say so plainly rather than sell you a third repair.
Prevention is genuinely effective on heat pumps in this climate, more so than on furnaces, because the outdoor unit lives outside in salt air and rain year-round. Annual service — coil cleaning, checking defrost operation before the first cold snap, tightening electrical connections, verifying charge and airflow — catches drifting sensors and pitting contactors before they become February no-heat calls.
If you are in a strata, keep your documentation on outdoor unit placement and noise limits; replacements often need approval, and that paperwork is easier to gather in advance.
Call HeatLand at (604) 330-3812. Serving Metro Vancouver and the Fraser Valley since 1999, licensed, insured, TSBC-certified, financing available.
Quick Checklist
- Write down the exact LED colour, flash count and rhythm — and which unit it is on — before cutting power, because a reset erases it.
- Photograph the model and serial number from the rating plate and the code legend printed inside the cabinet panel.
- Check the fault history menu on a communicating wall control and note how many times the fault has repeated.
- Replace or inspect the air filter and confirm return grilles and supply registers are open and unobstructed.
- Clear snow, ice, leaves and cedar debris from around the outdoor unit and make sure it is not sitting in frozen standing water.
- Confirm the thermostat is set to HEAT rather than EM HEAT, has power, and that the breaker and outdoor disconnect are on — then call (604) 330-3812 rather than resetting a pressure lockout repeatedly.
| Fault category | What you may notice | Homeowner or technician |
|---|---|---|
| Defrost / outdoor sensor | Outdoor unit iced over, constant defrost cycles, backup heat running nonstop | Homeowner clears debris and ice around the unit; technician tests sensor resistance and connections |
| Pressure lockout (high or low) | Compressor stops and will not restart, repeated shutdowns after short run times | Homeowner checks filter and airflow only; technician puts gauges on — do not repeatedly reset |
| Low-voltage / communication | Thermostat blank or showing a link error, system unresponsive, intermittent operation | Homeowner checks thermostat power and mode; technician traces wiring, transformer and connections |
| Compressor or outdoor fan motor | Loud hum with no start, outdoor fan not turning, breaker tripping | Technician only — capacitors hold a dangerous charge after power is cut |
| Reversing valve / wrong mode | Cool air from vents during a heat call outside of a normal defrost cycle | Homeowner confirms it is not defrost; technician checks solenoid, O/B logic and valve operation |
Frequently Asked Questions
What does a specific Tempstar error code number mean?
It depends entirely on your model and board revision, which is why we do not publish a code chart. The same flash pattern can mean different things across Tempstar generations. Read the exact code off your unit, then check it against the legend printed on the label inside the cabinet or your model’s installation manual. If you cannot find either, note the code, model and serial number and call HeatLand at (604) 330-3812 and we will interpret it against the correct documentation.
Is it safe to reset my heat pump after a fault code?
One reset to clear a possible one-off glitch is reasonable. Repeated resets are not. Pressure lockouts and compressor protection faults exist to stop the system before damage occurs, and forcing it to restart into a genuine fault can shorten compressor life significantly. If the same code returns, treat it as real information rather than a nuisance. Photograph the code first, because resetting usually erases it and the technician loses the most useful clue.
Why does my Tempstar heat pump ice up so much in Vancouver winters?
Some frosting is normal — every air-source heat pump builds frost on the outdoor coil and runs periodic defrost cycles to clear it. Our winters sit in a damp, near-freezing range that produces frost faster than drier climates do, so you will see more defrost activity here than a chart from elsewhere suggests. The problem is when it never clears: solid ice encasing the coil, or ice building under the unit and blocking drainage. That points to a defrost control or sensor issue worth diagnosing.
My vents are blowing cool air but the thermostat says heat. Is that a fault?
Not necessarily. During a defrost cycle the heat pump deliberately runs in reverse for a few minutes to melt the outdoor coil, and the supply air turns cool. That is normal and it ends on its own. If cool air persists well beyond a short cycle, the likely candidates are a reversing valve that has not shifted, a thermostat configured with the wrong O/B logic, or an outdoor unit that is not running at all while backup heat carries the load.
Can I clean the outdoor coil myself?
You can safely clear leaves, cottonwood fluff, snow and cedar debris from around and off the outside of the cabinet with the power off at the disconnect, and rinse the fins gently with a garden hose from the outside in, never a pressure washer. Do not open the electrical compartment, do not bend fins with a screwdriver, and do not use acid coil cleaners. A proper cleaning goes deeper than the surface, and near salt water it should be paired with a corrosion inspection.
Does HeatLand service Tempstar heat pumps across the Fraser Valley?
Yes. HeatLand serves Metro Vancouver and the Fraser Valley and services all major brands, including Tempstar. We are licensed, insured and TSBC-certified for gas work, which matters on dual-fuel systems pairing a heat pump with a gas furnace. Every diagnosis comes with an explanation of what we found and a free written, no-obligation estimate before any work starts. Call (604) 330-3812. Family-run here since 1999, and financing is available.
Reviewed by the HeatLand Heating & Cooling team — licensed, insured, TSBC-certified HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. Error codes, specifications, pricing and rebate programs vary by model and change over time; confirm details against your unit’s own manual, a written quote, and the manufacturer or CleanBC/FortisBC. If you smell gas or your CO alarm sounds, leave the home and call the gas utility and a licensed technician from outside.