Quick answer: Many “heat pump not heating” problems are simple — a nudged thermostat, a tripped breaker, or a scheduled off-period. Check those first. A frozen outdoor unit is usually normal in Scottish winters. Persistent ice, error codes you can’t clear, or a unit that runs but won’t warm the house need a professional.
When your heat pump stops putting out heat on a cold Scottish morning, it’s alarming. The good news: a fair share of these calls turn out to be something simple. Here’s how to work through it calmly.
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Heat Pump Not Working? Start With These Quick Checks
Before assuming the worst, rule out the basics — the heat pump equivalent of checking the plug is switched on. Four quick checks solve a large share of “not heating” calls, and you can do all of them yourself.
Check the thermostat.
Make sure it’s set to the correct mode (heating, not cooling or off) and that the target temperature is set a few degrees above the current room temperature — otherwise the system has no reason to fire. Also confirm it isn’t sitting in a scheduled off-period doing exactly what it was told.
Examine the air filters
This is the one people forget. A dirty, clogged filter restricts airflow and can shut the system down to protect itself. Clean or replace the filters and you may well fix the problem on the spot — it’s the single most common self-solvable cause.
Inspect the outdoor unit.
Check the outdoor fan is clear of leaves, debris and deep snow, and that nothing is blocking airflow around it. If it’s completely covered in ice, wait for it to thaw or run the defrost setting (more on icing below).
Check the breakers.
Look at both your main electrical panel and the outdoor disconnect/isolator box to make sure no breakers have tripped. A tripped breaker is a very common reason for a unit showing no signs of life.
A surprising number of “faults” come down to one of these four — a nudged thermostat, a clogged filter, a blocked outdoor unit or a tripped switch. Rule them out and you may save a callout entirely.
Why Is My Heat Pump Not Producing Any Heat?
If there’s no warmth and no signs of life, the usual causes are power and controls — a tripped breaker, a protective shutdown, or lost controller settings.
Restoring power and checking for an error code tells you a lot. If the unit powers up but throws an immediate fault, stop poking and call someone — it’s protecting itself for a reason.
Can a Dirty Air Filter Stop a Heat Pump Heating?
Yes — a clogged air filter is one of the most common causes of a heat pump underperforming or shutting down, because it starves the system of airflow.
Filters are easy to forget because they’re out of sight, but they quietly collect dust and debris until airflow drops enough to trip a protective shutdown or leave rooms cold. Cleaning or replacing them is a simple job you can do yourself, and it’s worth building into a regular routine rather than waiting for a problem.
If your heat pump is off or struggling, checking the filters should be one of the very first things you do — clearing debris and changing filters are exactly the sort of tasks a visual step-by-step guide can walk you through, and they need no special tools.
Why Is My Heat Pump Running but the House Is Cold?
This is usually a delivery problem, not a dead unit — trapped air in radiators, a circulation fault, or a flow temperature set too low for the weather.
If the heat pump is clearly working — you can hear it, the outdoor unit is active — but rooms aren’t warming, the heat is often stuck where you can’t feel it. It can also be a demand-versus-design mismatch showing up on the coldest days, a hint the setup deserves a proper look rather than a quick reset.
Why Won’t My Heat Pump Reach Temperature When It’s Cold?
A well-designed system holds its own through a Scottish winter. If yours consistently can’t reach temperature in the cold, that points to sizing, settings or a component issue — not the weather alone.
There’s a difference between “struggling because it’s genuinely freezing and fighting to keep up” and “not performing as it should.” Consistent underperformance in the cold is worth investigating.
Is It Normal for a Heat Pump to Freeze or Ice Up?
Yes — light frost or ice on the outdoor unit is completely normal in cold, damp weather. Heat pumps run an automatic defrost cycle to clear it. Ice that never clears or returns immediately is not normal.
| What you see | Normal or fault? | What to do |
|---|---|---|
| Light frost, clears on defrost | Normal | Nothing — it’s working |
| Brief heating dip, steam, change in sound | Normal (defrost cycle) | Nothing |
| Heavy ice that never clears | Fault | Call an engineer |
| Ice returns immediately after defrost | Fault | Call an engineer |
During defrost the unit briefly pauses heating, melts the ice, and carries on — you might see steam and hear it change note. That’s the system working as designed. Living in Scotland you’ll see plenty of harmless frosting each winter; the skill is knowing the routine from the real fault, and when in doubt, ask.
What Do Heat Pump Error Codes Mean?
Error codes flag problems on the controller and narrow things down fast — but note the exact code before clearing anything, as some mean a simple reset and others a component fault.
The code is the single most useful thing you can give whoever comes to look — it can turn a diagnostic visit into a quick, targeted fix. Don’t clear it before writing it down.
When Should You Call a Heat Pump Engineer?
Call for any error code you can’t resolve, ice that won’t clear, a unit that repeatedly trips the power, strange noises, leaks, or a system that runs but won’t heat.
Poking further risks making things worse — heat pumps are refrigerant systems that need qualified hands for anything beyond the basics. There’s no shame in calling early.
Local Heat Pump Repairs Across Edinburgh and Central Scotland
One frustration with heating faults is waiting days for someone who has to travel. Because we’re based in Edinburgh and work right across central Scotland, we can get to you without the long wait — and we know exactly the winter conditions that cause both real faults and the harmless ones people mistake for faults.
If you’ve run the checks and your heat pump still won’t heat, book a repair visit with our local engineers — we’ll diagnose it properly and, more often than not, get you warm again quickly.
