Truck/Trailer Refrigeration Unit - Sunbelt Transport Refrigeration

The CPR valve should be fully open. The coil shouldbe clean and free of ice.Remove the Presstolite from both bulbs and loosenthe clamps. Put a thermocouple above (parallel) TXVbulb next to each bulb. Retighten clamp and re-insulatewith Presstolite. Make the standard adjustment to bothexpansion valves which is unscrew completely thesuperheat setting screw in the counter-clockwisedirection. Then, tighten three turns (3X360˚) intheclockwise direction.Allow the unit to stabilize at 0˚C, makingsure that theunit is in high speed cool.Note the temperature of the suction gas at theexpansion valve bulb.Subtract the saturation temperature taken from thesuction gauge to determine superheat.Adjust each valve, a ¼ turn at a time, allowing the unitto stabilize between adjustments. Always adjust bothvalves equally to avoid priority of refrigerant to anyevaporator coil.4.31 REPLACING EVAPORATOR FAN MOTORRemove two retaining screws which hold the doorassembly in position. The complete hinged assemblydrops down, allowing access to the fan.Disconnect wires in terminal box relative to fan beingremoved. Remove four bolts and fan assembly.Fit new fan to mounting plate. Install fan assemblyinto evaporator.4.32 EVAPORATOR COIL CLEANINGThe use of recycled cardboard cartons is increasingacross the country. The recycled cardboard cartonscreate much more fiber dust during transport than “new”cartons. Fiber dust and particles are drawn into theevaporator where they lodge between the evaporatorfins. If the coil is not cleaned on a regular basis,sometimes as often as after each trip, the accumulationcan be great enough to restrict air flow, cause coil icing,repetitive defrosts and loss of unit capacity. Due to the“washing” action of normal defrost the fiber dust andparticles may not be visible on the face of the coil but mayaccumulate deep within.Theevaporatorcoilshouldbecleanedonaregularbasis, not only to remove cardboard dust, but to removeany grease or oil film which sometimes coats the fins andprevents water from draining into the drain pan.Cardboard fiber particles, after being wetted anddried several times, can be very hard to remove.Therefore, several washings may be necessary.a. Remove rubber check valves (Kazoo) from drainlines.b. Spray coil with a mild detergent solution such asOakite 164 or any good commercial grade automatic dishwasher detergent such as Electrosol or Cascade and letthe solution stand for a few minutes. Reverse flush(opposite normal air flow) with clean water at mildpressure. A garden hose with spray nozzle is usuallysufficient. Make sure drain lines are clean.c. Run unit until defrost mode can be initiated to checkfor proper draining from drain pan.4.33 EVAPORATOR ELECTRICALCONNECTIONSAll wiring harnesses to the evaporator section areidentical. The only difference is the length.WARNINGFor safety, when disconnecting the harnessat the condensing section end for testingpurposes, always leave the separate earthcable connected.A seventeen core cable is provided with a multi-pinconnector on one end to connect directly to thecondensing section. The other end of the cable is colorcoded to allow easy connection in the evaporator. Whenthere are two wires of the same color, they will benumbered: i.e. yellow (1) yellow (2) / brown (1) brown(2)ColorYellow 1Yellow 2Black 1Black 2OrangeGreyRedWhiteRedPurpleRedDark blueGreenBlueBrownGreen/YellowWireDefrost termination sensorReturnairsensor(B)Returnairsensor(A)Heater element safety klixonDoor switchHeater elementLiquid line solenoid valveHeater elementHot gas solenoid valveHeater elementDoor switchEarthLive from alternatorNeutral --- ” --- alternatorEarth4-27 62-02884