TL;DR

No coolant flow is most often low tank level, a clogged filter, or a failed pump. Check the tank level first, then clean the sump filter before replacing the pump.

What you might see

no coolant at the nozzles
low coolant warning active
coolant pump running but no flow
coolant leaking onto the floor

Likely causes

Tap to mark as ruled out

Low coolant level triggering the low-level cutout switch
Clogged sump filter or chip strainer blocking pump suction
Failed coolant pump motor or impeller
Cracked or disconnected coolant line or nozzle fitting

Required tools

LOTO kit
Nitrile gloves and safety glasses
Bucket and rinse hose for filter cleaning
Refractometer for coolant concentration check
Replacement coolant (correct type per Haas spec)

Safety first

Coolant and coolant concentrate are skin and eye irritants. Wear nitrile gloves and safety glasses when handling.
Lock out the machine before opening the electrical panel to check the pump breaker.
Do not run the coolant pump dry. A running dry pump will fail within minutes.

Procedure

7 steps · ~25 min

1
Open the coolant tank access panel and check the coolant level. Top up to the full mark with the correct Haas-recommended coolant concentration.[1]
2
Inspect the sump filter screen at the tank pickup. Remove it and rinse it clean under running water. Chip buildup on this screen is the most common cause of lost flow.[1]
3
Check the Haas controller coolant alarm. If the LOW COOLANT alarm is active after topping up, inspect the float switch for debris or a stuck float.
4
With the machine door closed and coolant commanded on from MDI (M08), listen and watch for pump noise. No noise from the pump area indicates a tripped pump thermal or failed pump motor.
5
Check the coolant pump circuit breaker on the Haas electrical panel. Reset it if tripped. If it trips again immediately, the pump motor is shorted and needs replacement.
6
If the pump runs but flow is low, remove the nozzle lines and check for kinks, blockages, or disconnected push-to-connect fittings.
7
Inspect the coolant tank for chip accumulation and clean the tank sump. Heavy chip loading reduces coolant capacity and clogs filters rapidly.
Warning: Coolant concentrate is an irritant. Use nitrile gloves and eye protection when handling coolant or cleaning the sump.

Sources

Haas VF Series Operator's Manual, Haas Automation Inc.
Haas VF Series Operator's Manual, general coolant system maintenance and filter cleaning procedures (general)
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