MAXX 450D/470D/Diesel Page 6-9
HydraMaster Corporation
10/24/02
1.0. Will not come up to normal cleaning pressure
1.1. Pressure adjusting valve is defective or dirty. Disassemble valve. Repair or replace
as necessary.
1.2. Worn seals or valves in pump. Test pump output volume directly from pump at normal
operating RPM. If volume is below manufacturers specifications, replace seals and
inspect for defective valves.
1.3. Pump RPM is too low. Check engine RPM and adjust as necessary. Check for loose
pump belt. Adjust tension as necessary.
1.4. High temperature dump solenoid is activated. Refer to Heating System section IV.
1.5. Primary system control orifice is missing or loose. Remove filter and inspect. Tighten
or replace as necessary.
1.6. Primary system control orifice has been exchanged with secondary (hot water
dump) orifice. Inspect and reverse as necessary.
1.7. Primary orifice is worn. Measure orifice size and replace as necessary.
2.0. No pressure reading on PSI gauge
2.1. Pump switch is not turned on. Turn on switch
2.2. No water in mix tank. Refer to section 5.0
2.3. Pump belt is broken. Replace belt.
2.4. Pump clutch is not activated. There is no water in water box. Check system back to
source to locate cause of interruption to water flow.
2.5. Pump clutch is not activated. There is water in the water box. Check for 12 volts at
clutch. If 12 volts is present, replace clutch.
2.5.1. If 12 volts is not present, check fuse that supplies power to the low-water relay. If fuse is
good and there is 12 volts at the relay, check low water switch in water box.
2.5.2. If low water switch has no continuity when float is up, replace the switch. If switch is
good, replace the low water relay.
High Pressure System
Troubleshooting
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