Carrier GR-45 Operation And Service

Contents

Carrier GR-45 Operation And Service Manual pdf 40 page image

T-2954-74.13 EVAPORATOR COIL REPLACEMENTa. If refrigerant remains in the system, perform a lowside pump down to remove refrigerant from the evap-orator coils.CAUTIONIf unit was recently operated, be careful ofremaining hot coolant in the hoses when dis-assembling.b. Remove fresh air intake.c. Drain heater coil by removing the required coolantfrom the engine cooling system.d. Remove 12 mounting screws, 4 each at the receiversupport, at the front of the unit and at the return airopening.e. Remove the electronic board and harness.f. Remove the filter--drier.g. Disconnect suction line hose and lift coil out of unit.h. To install the coil assembly, reverse the removal pro-cedure.4.14 SERVICING THE HEAT VALVEThe heat valve (Figure 4-9) requires no maintenanceunless 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 impropervoltage to the coil.There are only three possible valve malfunctions: coilburnout, 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 ofthe coil housing or plunger.4. Mechanical interference with movement of plungerwhich 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 assem-bly.2 Foreign material in the valve.3 Torn diaphragm.4.14.1 Coil Replacementa. It is not necessary to drain the coolant from the sys-tem.b. Place main battery disconnect switch in OFF positionand lock.c. Disconnect wire leads to coil.d. Remove coil retaining screw and nameplate.e. Lift burned-out coil from enclosing tube and replace.f. Connect wire leads and test operation.4.14.2 Internal Part Replacementa. Place main battery disconnect switch in OFF positionand lock.b. Open the vent fitting at the top of the outlet header ofthe heater coil.c. Drain coil by opening the drain-cock on the inlet tube.d. Disassemble valve and replace defective parts.e. Assemble valve, refill and bleed coolant lines.4.14.3 Replace Entire Valvea. Place main battery disconnect switch in OFF positionand lock.b. Drain coolant from lines as previously described anddisconnect hoses to valve .c. Disconnect wire leads to coil.d. Remove valve assembly from bracket.e. Install new valve and re-connect hoses. It is not ne-cessary to disassemble the valve when installing.f. Refill and bleed coolant lines.g. Connect wire leads and test operation.123456789101. Coil Retaining Screw2. Nameplate3. Coil HousingAssembly4. Enclosing Tube &Bonnet Assembly5. Kick-Off Spring6. Plunger7. Closing Spring8. Diaphragm9. O-Ring10. Valve BodyFigure 4-9. Heat Valve