Valve Troubleshooting; Hot Water Circulating Pump - PREVOST H3-41 Maintenance Manual

4.12.1

Valve Troubleshooting

PROBLEM
Valve fails to close
Valve fails to open
4.13

HOT WATER CIRCULATING PUMP

4.13.1 Central HVAC System
The vehicle is provided with a seal-less/brushless water circulating pump which is located in:
• H3 Series - evaporator compartment
• X3 Series - coolant preheater compartment (Figure 61)
Additional circulating pump in the first curbside baggage compartment with optional upper
•
windshield defrost unit
FIGURE 60: HOT WATER CIRCULATING PUMP INSTALLATION (H3 SERIES CENTRAL HVAC SYSTEM)
1. Check electrical supply with a voltmeter. It should agree with nameplate
rating.
2. Check pressure at pilot solenoid valve inlet. It must be at least equal to the
minimum pressure stamped on the nameplate. It should not go below
minimum while valve is operating.
1. Check that the closure member assembly, and that main actuator and
cylinder springs are free to travel.
2. Check that there is no restriction to the air escaping from the actuator
casing.
3. Make sure that pilot solenoid valve operates properly.
PA1621 Maintenance Manual All Series | Revised February 2019
SECTION 22: HEATING AND AIR CONDITIONING
PROCEDURE
43