Direct answer: If an HRV or ERV is not working, the most common causes are lost power, a tripped service switch or breaker, a wall control setting issue, heavily clogged HRV / ERV filters, or a unit that has shut down because airflow is restricted or the core area is iced up.
Most likely: Start by confirming the unit actually has power and is being called to run, then check the HRV / ERV filters, outdoor hoods, and accessible core area for blockage before assuming a motor or control failure.
HRVs and ERVs can fail in a few different ways: completely dead, powered but not moving air, running only on some speeds, or shutting down in cold or damp conditions. Separate those branches first. Safe homeowner checks are mostly visual and basic power checks. If the diagnosis points to internal wiring, a failed motor, or an electronic control problem, it is usually time for service.
Don’t start with: Do not start by buying an HRV / ERV fan motor or control board. Many no-run complaints turn out to be a switch, breaker, dirty filter, blocked intake or exhaust, or a control setting problem.
The unit seems completely dead. Wall control changes do nothing, and you do not hear the fans.
Start here: Start with power to the unit: breaker, service switch, plug, disconnect, and any accessible fuse or reset on the unit.
A control appears active, but supply or exhaust airflow is weak or absent.
Start here: Check filters, outdoor intake and exhaust hoods, and the core area for dirt, blockage, or frost before suspecting a motor.
The unit may run on boost but not low speed, or it may start and stop unpredictably.
Start here: Check wall control settings, timers, humidity controls, and whether one fan path is restricted enough to trigger a shutdown or poor performance.
Airflow dropped or the unit stopped after freezing temperatures or heavy condensation.
Start here: Look for iced intake or exhaust hoods, a frozen or blocked core area, or a condensate drain problem if your unit uses one.
A dead HRV / ERV is often caused by a tripped breaker, switched-off disconnect, loose plug, or wall control issue rather than a failed internal part.
Quick check: Confirm the breaker is fully on, any nearby service switch is on, the unit is plugged in if applicable, and the wall control is not in off, standby, or timer-only mode.
Restricted airflow can make the unit seem weak, noisy, or nonfunctional, and some units reduce operation when airflow is badly limited.
Quick check: Remove and inspect the filters, then check both outdoor hoods for lint, leaves, snow, insect screens, or ice.
In cold weather, frost or ice can choke airflow. Dirt buildup can also reduce performance enough to look like a failure.
Quick check: Open only the normal service access panel and inspect the accessible core area for heavy dust, standing water, or ice.
If power is present, controls are calling for operation, airflow paths are clear, and the unit still will not run, an internal component may have failed.
Quick check: Listen for humming, repeated clicking, or one fan running while the other stays still. That pattern points away from a simple filter issue.
A surprising number of HRV / ERV no-run calls are caused by a simple power or control issue.
Next move: If the unit starts after restoring power or correcting the control setting, monitor it through a full run cycle and move to prevention so the issue does not repeat. If the unit still appears dead or unresponsive, continue to airflow and access-panel checks before assuming an internal failure.
What to conclude: If power was off, the problem may be external to the HRV / ERV. If power is present but the unit does not respond, the fault is more likely inside the unit or its controls.
Dirty filters and blocked intake or exhaust hoods are common, safe-to-check causes and can make the unit seem dead or ineffective.
Repair guide: How to Clean a Hrv / Erv Filter
What to conclude: A restriction on either side can reduce ventilation enough to mimic a motor or control problem.
A dirty or iced core area can block airflow, and standing water can point to a drain or defrost problem.
Repair guide: How to Clean a Hrv / Erv Core
This helps you avoid guessing between a wall control issue, a failed fan, and a deeper electronic fault.
Next move: If the unit responds normally after cycling settings and reinstalling cleaned components, the issue was likely a control setting or airflow restriction rather than a failed part. If one fan stays off, both fans stay off with power present, or the unit only hums or clicks, internal diagnosis is now more likely than a simple maintenance issue.
At this point, the safe easy checks are done, and the remaining branches usually involve fitment, wiring, or internal component testing.
A good result: If the unit now runs steadily with normal airflow, you likely solved a maintenance or control branch and do not need parts yet beyond routine filters.
If not: If the unit still fails after these checks, professional diagnosis is the safest next step.
What to conclude: A confirmed internal fan, control, or defrost fault is possible, but those are not good guess-and-buy repairs for most homeowners.
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The most common reasons are a tripped breaker, switched-off service disconnect, loose plug, or a wall control set to off or standby. If power is confirmed and the unit is still dead, the problem may be internal and usually needs service.
Yes. Heavily clogged HRV / ERV filters can cut airflow so much that the system seems dead or ineffective. Some units also behave poorly or shut down when airflow is badly restricted.
Not first. Weak or missing airflow is often caused by dirty filters, blocked outdoor hoods, frost, or a dirty core area. A fan motor becomes more likely only after those branches are ruled out and the unit still has confirmed power and a run command.
Check for snow or ice at the outdoor hoods and inspect the accessible core area for frost or internal ice. Repeated freeze-ups can point to airflow restriction, drainage trouble, or a defrost problem and often need professional diagnosis.
Only if the core is user-serviceable and your unit's routine maintenance instructions allow removal and cleaning. Some cores are delicate and can be damaged by the wrong method. If you are unsure, stop after a visual inspection and get model-specific guidance or service.