"No flow" almost never means the pump is dead. Here's how our techs actually work through it — in order, cheapest and most likely first — plus real jobs we've closed out.
Cheapest and most likely causes first — this is the same sequence our techs run on a service call.
A clogged filter is the single most common reason for reduced or zero flow. Pull it and look — mold, biofilm, or debris buildup can choke flow down to nothing on an otherwise healthy system.
A hum with no spin usually means a seized or jammed impeller. Total silence points to a power problem reaching the pump — check its power supply specifically, not just the chiller's.
A flow sensor reading low or zero doesn't always mean the pump has failed — air in the line or a fouled sensor can throw a false reading. Check the actual return jet before assuming the worst.
Confirm the old filter was actually swapped during the job, and that the new pump's power connector genuinely matches your unit — both are real, documented causes of "new pump, still no flow."
Anonymized from actual service visits — city, brand, and what our tech actually found on site.
Zero flow, pump completely inoperable. Replaced the water pump, both power supplies, and the filter housing, then replumbed with the correct venturi fitting for the manufacturer's kit.
Pump had been replaced by another visit, but the original filter was left in place — completely filled with black mold and biofilm, choking flow on its own regardless of pump health.
Not a total failure — the impeller was loose and spinning inconsistently rather than smoothly, which read as intermittent low flow rather than a dead pump.
The most common cause by far is a clogged filter — check and rinse it before anything else. After that, listen at the pump: a hum with no spin usually means a seized or jammed impeller, while total silence points to a power problem reaching the pump specifically. Less common but real: a loose or worn impeller that spins inconsistently instead of failing outright.
Flow sensors can read wrong, especially if there's air in the line or the sensor itself is fouled. Before assuming the pump is failing, check what you can actually see and feel at the return jet against what the display is reporting — a mismatch points to the sensor, not the pump.
Check two things first: whether the old filter was actually swapped during the install, and whether the new pump's power supply plug actually matches your unit — mismatched connectors on replacement parts are a real, documented install issue, not a defective pump.
Yes — a filter that's gone untouched for months, especially one that's built up mold or biofilm, can restrict flow down to almost nothing even with a completely healthy pump. It's the first thing we check because it's the cheapest and fastest fix if that's all it is.
A pump that's warm or hot to the touch, a breaker that trips on startup, or standing water near any electrical connection. Unplug it and call — that's not a DIY situation. Text or call (619) 289-9282.
Every diagnostic visit includes a full inspection, not just the symptom you called about — and a same-day report with photos.