Chiller Isn't CoolingUpdated 3 hours ago
If your chiller is running but the water isn't reaching your target temperature (or is taking longer than expected) work through the checks below. In most cases it's about giving the unit what it needs to cool efficiently, not a fault. Work through each one, and if you still need us, the temperature test at the end gives our team exactly what we need to help fast.
First, give it enough time
Chillers don't cool instantly. The Ultra X1 and X2 can take 12–16 hours to reach their lowest temperature. We recommend running the chiller overnight, ideally during the cooler part of the day, ahead of your intended plunge. If you're checking a couple of hours in, it may simply still be working.
Quick checks (start here as these resolve most cases)
1. Check your filters
- Brand new chiller? Make sure the plastic wrapping has been removed from the large filter this is a common one and completely blocks flow if left on.
- Been using it a while? Filters should be clean and free of debris blockages significantly reduce cooling efficiency.
- Both filters should be washed weekly, and the large filter replaced every 2–3 weeks to maintain flow and temperature control. See Filter Maintenance Full Guide.
2. Check your water level
- The recommended level is approximately 5–7 cm (2–3 inches) below the inlet hole.
- Don't overfill. Too much water creates an imbalance between volume and cooling capacity, and the unit may never reach target.
- That said, your water level must be above your unit for the unit to work. Keep this in mind when it comes to your tub and chiller placement.
3. Check ambient conditions
- The surrounding environment has a big effect on performance.
- Make sure the chiller is in a well-ventilated area, away from direct sunlight and heat sources. A hot or enclosed spot forces the unit to work against its environment.
Step-by-step diagnosis (if the quick checks didn't resolve it)
Verify your key settings (P1, P2, P3)
To access these, hold the temperature icon button for several seconds until the display changes, then scroll through P1, P2, and P3.
- P1 — Temperature Hysteresis. Controls how often the chiller cycles back on after hitting your set temperature. Example: at a 3°C target with P1 set to 2°C, the unit stops at 3°C and restarts at 5°C. (Range 0.1–10°C | Default 2°C)
- P2 — Compressor Start-Up Delay. A short delay before the compressor restarts, protecting against over-cycling. (Range 1–5 min | Default 3 min — we recommend leaving this unchanged.)
- P3 — Display Temperature Calibration. Corrects discrepancies between the chiller display and an external thermometer. If your water feels cold but the display reads high (or vice versa), this is worth checking a miscalibrated display can look like a cooling problem when the water is actually fine.
Run a temperature test
This is the single most useful thing you can do before contacting us:
- Run the chiller for 10–15 minutes.
- Record the temperature at the start and end of that period.
- Note whether it drops, stays stable, or rises.
- Confirm whether you can hear the compressor running and see the fans spinning.
When to contact us
If you've worked through the checks and it's still not cooling, contact support and send us:
- Your order number and model
- Your start and end temperatures from the 10–15 minute test
- Whether the temperature dropped, held, or rose
- Whether the compressor is audible and the fans are spinning
- Which checks above you've already tried
That information lets our technical team diagnose quickly rather than asking you to repeat steps.
Stop this happening again
The two most common causes of weak cooling are an overdue filter and a poorly ventilated spot. Staying on top of both keeps performance consistent:
- Wash filters weekly, replace the large filter every 2–3 weeks
- Keep the unit ventilated, out of direct sun, away from heat sources
- Run overnight ahead of your plunge for the coldest, most reliable results