4-9
4.15 SERVICING THE REHEAT COOLANT VALVE
The coolant valve requires no maintenance unless a
malfunction to the internal parts or coil occurs. This may
be caused by foreign material such as: dirt, scale, or
sludge in the coolant system, or improper voltage to the
coil.
To service the valve includes replacement of the
internal parts shown in Figure 4-9 or the entire valve.
There are only three possible valve malfunctions: coil
burnout, failure to open, or failure to close.
Coil burnout may be caused by the following:
1. Improper voltage.
2. Continuous over-voltage, more than 10% or
Under-voltage of more than 15%.
3. Incomplete magnetic circuit due to the omission
of the coil housing or plunger.
4. Mechanical interference with movement of
plunger which may be caused by a deformed enclosing
tube.
Failure to open may be caused by the following:
1. Coil burned out or an open circuit to coil
connections.
2. Improper voltage.
3. Torn diaphragm.
4. Defective plunger or deformed valve body
assembly.
Failure to close may be caused by the following:
1. Defective plunger or deformed valve body
assembly.
2. Foreign material in the valve.
a. To replace a burnout coil, it is not necessary to drain
the coolant from the system.
1. Place the run control switch in the “OFF”
position.
2. Disconnect wire leads to coil.
3. Remove coil retaining screw and nameplate.
4. Lift burned-out coil from enclosing coil assembly
and replace.
5. Connect wire leads and test operation.
b. To replace the internal parts of the valve:
1. Place the run control switch in the “OFF”
position.
2. Open the vent fitting at the top of the outlet
header of the heater coil.
3. Drain coil by removing enough coolant from
vehicle cooling system.
4. Disassemble valve and replace defective parts.
5. Assemble valve and connect coolant hoses.
c. To replace the entire valve:
1. Drain coolant system and disconnect lines to valve
as previously described.
2. Disconnect wire leads to coil.
3. Remove valve assembly from bracket.
4. Install new valve and re-connect lines. It is not
necessary to disassembly the valve when installing.
5. Fill system with coolant and bleed air through the
vent fitting.
6. Connect wire leads and test operation.
1
2
3
4
5
6
7
8
10
9
1. Coil Retaining Screw
2. Nameplate
3. Coil Housing Assembly
4. Enclosing Tube &
Bonnett Assembly
5. Kick-Off Spring
6. Plunger
7. Closing Spring
8. Diaphragm
9. O-Ring
10. Valve Body
Figure 4-9. Reheat Coolant Valve Assembly