Why Is My Dyson Hot+Cool HP04 Not Heating
- Heat mode not enabled
- Target temperature below room temp
- Blocked filters
Problem Description
Heating can fail if the unit is in cooling mode, the target temperature is too low, or filters are blocked. This guide checks mode settings and restores heating.
Why This Happens in Real Homes
Heating can fail if the unit is in cooling mode, the target temperature is too low, or filters are blocked. This guide checks mode settings and restores heating. In day-to-day use, this usually looks like Airflow stays cool; Heat mode selected but no warmth; Target temperature set low.
Most cases trace back to Heat mode not enabled; Target temperature below room temp; Blocked filters. The fix works best when you go step by step instead of changing multiple settings at once.
A practical order for this issue is: Confirm Heat Mode -> Increase Target -> Check Filters -> Test Without Auto. After each step, test the exact behavior that was failing so you can confirm what actually solved it.
Symptoms
- Airflow stays cool
- Heat mode selected but no warmth
- Target temperature set low
- App shows heating on
- Filter warning on
- Unit recently cleaned
Recognize these? Here's what usually causes it.
Common Causes
- Heat mode not enabled
- Target temperature below room temp
- Blocked filters
- Auto mode overriding heat
- Firmware outdated
- Room temperature sensor dirty
Most fixes happen in the first 3 steps.
Do not cover the air inlet or outlet while troubleshooting heating.
Tools & Requirements
Step-by-Step Solution
Confirm Heat Mode
Use the remote or app to set the unit to Heat mode.
Increase Target
Set the target temperature above current room temperature.
Check Filters
Remove and clean or replace filters if the warning light is on.
Test Without Auto
Disable Auto mode to confirm the heater activates.
Update Firmware
Check the MyDyson app for any firmware updates.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If this comes back after following these steps, check whether a recent app or firmware update reset a default setting — the fix works, but the setting gets reverted silently.
Keep the purifier at least 3 feet from walls to avoid airflow restriction.
This issue almost always looks more complex than it is — the majority of cases trace back to a single setting, a stale credential, or a default that shipped wrong.
- Heat mode not enabled
- Target temperature below room temp
- Blocked filters
- Auto mode overriding heat
- Firmware outdated
Before you go — try one of these (they fix most cases).
Official Manufacturer Manual
If you need the complete manufacturer documentation for advanced setup, wiring diagrams, or detailed specifications, you can download the official manual below. The manual includes full technical instructions directly from the manufacturer and may help if your issue requires deeper troubleshooting.
Download the Official Dyson Hot+Cool ManualSource: dyson.com
Need More Help? Dyson Support
Note: The contact information below connects you directly to Dyson's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
