Blakeslee Conveyor Dishwasher Error Code M3: Prewash Cooling Failure
M3 PREWASH COOLING FAILURE means the prewash tank could not be cooled. The manual says to check that the cold water inlet connection is working, then turn the machine off and on after a few seconds. If it persists, call a service technician.
Medium: the prewash cannot be cooled, so cleaning results can suffer, but the machine is not stopped.
- Code
- M3
- Maker
- Blakeslee
- Equipment
- Conveyor dish machines
- Applies to
- RC-series rack conveyor with scrolling-text display and LED bar
What does Blakeslee error code M3 mean?
The prewash tank has a cooling function that uses cold water, and the control calls on it when the prewash temperature needs to come down. If the cooling does not work, the control shows M3 PREWASH COOLING FAILURE. The manual describes it as a prewash cooling failure. Its checks are that the cold water inlet connection is working, then a reset by turning the machine off and on after a few seconds; if the alarm persists, it says to contact Technical Service. A closed cold water valve, a blocked inlet, a cooling valve that does not open or a misreading prewash probe can all prevent cooling. M3 is about cooling the tank, so it is separate from M1, where the tank does not fill at all.
Affected models and control systems
Blakeslee RC-series rack conveyor dishwasher. The PDF is Blakeslee's RC44 User Manual and prints no model name; the same alarm list appears in the RC62 manual.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- M3 PREWASH COOLING FAILURE on the display
- Prewash tank water hot
- Soil baked on or sticking to dishes
- No sound of cold water entering
Possible causes
Likely causes — what usually sits behind error code M3 on this control. A technician confirms which one it is before any part is replaced.
- Cold water inlet closed or disconnected
- Cooling valve not opening
- Cold water line restricted by scale
- Prewash probe reading incorrectly
Safe checks before calling for service
- Check that the cold water inlet connection and its valve are open, as the manual says.
- Turn the machine off, wait a few seconds, and turn it on again.
- Look at whether dishes are coming out with baked-on soil.
- If M3 returns, stop and arrange service.
- Note whether the prewash felt hot and when the alarm appeared.
How a technician diagnoses error code M3
- Read the alarm history and note whether M2 is also present.
- Verify cold water pressure and clean the inlet strainer.
- Test the prewash cooling valve coil and voltage when cooling is requested.
- Check the prewash probe against a reference thermometer.
- Replace the failed valve, probe or control part.
- The prewash tank holds hot water and sits beside live wiring.
- Valve and probe tests are made on live circuits.
- Separating a valve failure from a probe failure requires a meter and thermometer.
How error code M3 differs from similar codes
M3 is prewash cooling. M1 is prewash filling and M2 the prewash probe.
Technical reference
- Maker documentation
- Blakeslee owner support
- Edition
- COD. 4950E_U_USA, Ed. 00 - 09/2016
- Models / control
- RC-series rack conveyor with scrolling-text display and LED bar
- Section
- Chapter 12.2.1 Alarms description (pp. 54-55)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Blakeslee conveyor dish machine error codes
Why does a prewash need cooling?
The prewash has a cooling function, and M3 means that function did not work.
Is M3 caused by the water supply?
It can be. The manual's first check is the cold water inlet connection.
Will a reset clear it?
Sometimes. If it returns, the cooling circuit needs a technician.
Need help with Blakeslee error code M3?
A technician confirms the cause on site and gives you the price in writing before any work starts.