Heater System Dodge Ram Van III

DESCRIPTION

All models use a blend-air system. Outside air enters heater through cowl opening and passes through a plenum chamber to heater core. A temperature control door in heater housing either directs incoming air through or around heater core.

Once past heater core, heated air and unheated air are mixed, producing air at desired temperature. Heater discharge is then directed through dash panel to air distribution duct in passenger compartment.

Ram Van/Wagon may have an optional rear heater assembly. The rear heater assembly consists of a combination coil and 3-speed blower motor enclosed in a housing. Rear heater assembly is mounted on floor, behind driver's seat.

Rear heater assembly's coolant flow control valve is engaged after instrument panel's temperature control lever is moved past its first quarter of travel. Rear heater blower speeds are controlled by a separate 4-position toggle switch mounted on instrument panel.

HEATER CONTROL PANEL

The front heater control panel contains a 4-position fan switch, a rotary temperature control switch and a rotary air direction control switch. The rear heater control panel contains a 3-position fan switch.

Fan Switch (Front)

Fan speed is controlled with a rotary switch. There are 4 different fan speed settings: one low speed, 2 medium speeds and one high speed.

Fan Switch (Rear)

Fan speed is controlled with a rotary switch. There are 3 different fan speed settings: one low speed, one medium speed and one high speed.

Mode Control Knob

A rotary mode switch is used to control airflow. There are 5 different modes of operation: panel, floor/panel, floor, floor/defrost and defrost.

Temperature Control Knob

Rotary control knob determines discharge air temperature by manually positioning temperature blend/air door. Temperature blend/air door is electrically operated. When a hot temperature is selected, all air flows through heater core.

HEATER PERFORMANCE

Check cooling system. Check serpentine drive belt tension. Check radiator airflow. Check radiator fan operation. Ensure that accessory vacuum supply line is connected at engine vacuum source.

* PLEASE READ FIRST *

BLOWER MOTOR RELAY

Note. Testing for high speed blower motor relay is similar.

1. Front blower motor relay is located in Power Distribution Center (PDC). Rear blower motor relay and high speed blower motor relay located in a connector attached to back of rear heater assembly, behind water valve.
2. Front high speed blower motor relay is located on side of heater assembly. Disconnect negative battery cable. Remove blower motor relay. Using an ohmmeter, check for continuity between terminals No. 87A and 30 of relay. (Scheme 1) If continuity does not exist, replace relay. If continuity exists, go to next step.
3. Using an ohmmeter, check for continuity between terminals No. 30 and 87 of relay. If continuity exists, replace relay. If continuity does not exist, go to next step.
4. Measure resistance between terminals No. 85 and 86 of relay. Reading should be 70-80 ohms. If reading is not as specified, replace relay. If reading is as specified, go to next step.
5. Using jumper wires, connect battery voltage to terminal No. 86 and ground terminal No. 85. (Scheme 1) Check that continuity exists between terminals No. 30 and 87. Check that continuity does not exist between terminals No. 87A and 30. If continuity is not as specified, replace blower motor relay. If continuity is as specified, relay is okay.

Scheme 1

BLOWER MOTOR RESISTOR

1. Disconnect negative battery cable. Disconnect blower motor resistor harness connector. Using an ohmmeter, check for continuity between all 4 (front blower motor resistor) or 3 (rear blower motor resistor) blower motor resistor terminals. If continuity exists, go to next step. If continuity does not exist, replace faulty blower motor resistor.
2. Check for open or short in circuits between blower motor resistor and heater control panel. Also check for open or short in wire between blower motor resistor and blower motor.

Front

1. Disconnect negative battery cable. Remove heater control panel. See «HEATER CONTROL PANEL R & I»(/dodge/ram-van/iii-1994-2003/remont/heater/#heater-system__heater-control-panel-r-i). Disconnect heater control panel harness connector. Using an ohmmeter, check for continuity between heater control panel C3 harness connector terminal "C" (Black wire) and ground. (Scheme 3) If continuity exists, go to step 3).
2. If continuity does not exist, repair open in Black wire between heater control panel and ground connector located at lower right of steering column.
3. Place heater mode control knob to any position except OFF. Using an ohmmeter, check for continuity between heater control panel C3 connector terminals "B" (Violet wire) and "C" (Black wire). If continuity exists, go to next step. If continuity does not exist, replace faulty heater control panel.
4. Using an ohmmeter, check for continuity between heater control panel C3 connector terminal "B" (Violet wire) and C1 connector terminal "E" (Violet wire). (Scheme 2) If continuity exists, go to next step. If continuity does not exist, repair open in Violet wire between heater control panel C3 and C1 connectors.
5. Using an ohmmeter, check for continuity between heater control panel C1 connector terminals "E" and terminals "B", "C" and "D" while rotating fan switch. (Scheme 2)
6. If continuity does not exist at any terminal, replace faulty heater control panel. If continuity exists as specified, check for open in circuits between heater control panel and blower motor resistor. Also check for an open in circuit between heater control panel connector and blower motor relay.

Scheme 2

Scheme 3

Rear

1. Disconnect negative battery cable. Remove accessory switch plate from instrument panel. See «ACCESSORY SWITCH PLATE»(/dodge/ram-van/iii-1994-2003/remont/heater/#heater-system__accessory-switch-plate) under REMOVAL & INSTALLATION. Disconnect rear blower motor switch connector. Check continuity between rear blower motor switch C1 connector terminal "E" (Black wire) and ground. (Scheme 2) If continuity exists, go to step 3).
2. If continuity does not exist, repair open in Black wire between rear blower motor switch and ground connector located at lower right of steering column.
3. Place fan switch knob to any position except OFF. Using an ohmmeter, check for continuity between rear blower motor switch C1 connector terminals "E" and terminals "B", "C" and "D" while rotating fan switch. (Scheme 2)
4. If continuity does not exist at any terminal, replace faulty accessory switch plate. If continuity exists as specified, check for open in circuits between rear blower motor switch and rear blower motor resistor. Also check for an open in circuit between rear blower motor switch connector and rear blower motor relay.

1. Connect a vacuum gauge in line with Black heater vacuum supply hose, located in engine compartment. Position gauge so it can be viewed from passenger compartment.
2. Start engine. While observing gauge, rotate mode control knob to each mode position (one position at a time). Pause after each selection. Test gauge should drop then return to 8 in. Hg. shortly after each selection is made. If gauge reading is as specified, go to next step. If gauge reading is not as specified, check for vacuum leak in vacuum lines or heater control panel.

HEATER OUTPUT

1. Start engine. Allow engine to reach normal operating temperature. With engine at idle, set controls to maximum heat, floor and high blower positions. Using a thermometer, check air temperature coming from floor vents. See «HEATER OUTPUT TEMPERATURE»(/dodge/ram-van/iii-1994-2003/remont/heater/#heater-system) table.
2. If floor outlet air temperature is lower than specified, check cooling system and electric cooling fan. See ENGINE COOLING FAN article.
3. Check that both return and supply heater hoses are hot. If coolant return hose is much cooler than supply hose, repair coolant obstruction in heater system. Check for air flow obstruction in heater system. Check blend air door for proper operation.

HEATER OUTPUT TEMPERATURE

ACCESSORY SWITCH PLATE

Removal & Installation

1. Disconnect negative battery cable. Disarm and remove passenger side air bag. See AIR BAG RESTRAINT SYSTEM article. On models equipped with A/T, unlock ignition switch. Set parking brake and place gear selector lever in "L" position.
2. If equipped, set tilt steering column in lowest position. Carefully pry bezel away from instrument panel to disengage clips. Pull bezel away far enough to clear trip odometer reset button. Remove bezel.
3. Remove engine cover from passenger compartment. If equipped, remove passenger side air bag disarm switch connector. Remove accessory switch plate-to-instrument panel screws.
4. Pull back accessory switch plate and disconnect cigarette lighter, auxiliary power outlet and rear blower motor switch. Remove accessory switch plate. Enable air bag system. See AIR BAG RESTRAINT SYSTEM article. To install, reverse removal procedure.

Removal (Front)

1. Disconnect negative battery cable. Remove top half of radiator shroud. At right side of engine compartment, disconnect blower motor wiring connector and motor cooling tube.
2. Remove nuts and washers from blower motor backing plate to heater housing studs. (Scheme 4) Remove blower motor assembly.
3. Place reference arks on blower motor and fan for installation reference. Remove blower motor fan retainer clip. Pull blower motor fan off blower motor shaft. Inspect backing plate seal for breaks and adhesion.

Installation

Align reference marks made during removal. Press blower fan hub onto blower motor shaft. Ensure retainer clip ears are indexed over flats of blower motor shaft and fan hub. Apply a small bead of rubber sealant to blower motor side of rubber seal. To complete installation, reverse removal procedure.

Removal & Installation (Rear)

Remove auxiliary heater assembly. See Removal & Installation (Rear) uner HEATER ASSEMBLY . Remove blower motor screws and remove blower motor from heater assembly. To install, reverse removal procedure.

Scheme 4

Removal & Installation (Front)

Blower motor resistor is located behind glove box, attached to dash plenum panel. Disconnect negative battery cable. Remove glove box bin. Disconnect blower motor resistor connector. Remove resistor retaining screws. Remove blower motor resistor. To install, reverse removal procedure.

1. Blower motor resistor is located inside rear heater assembly, behind horizontal duct outlet. Turn ignition on. Place temperature control knob to full hot position. Turn ignition off. Disconnect negative battery cable. Remove rear heater assembly. See «HEATER ASSEMBLY»(/dodge/ram-van/iii-1994-2003/remont/heater/#heater-system).
2. Remove rear heater assembly cover. Reach under front of rear heater assembly and disconnect rear blower motor resistor harness connector. Remove horizontal duct from rear heater assembly.
3. Using pliers, reach through horizontal duct outlet in rear heater assembly upper housing. (Scheme 5) Push firmly against rear blower motor resistor until it unsnaps from retainer. Remove rear blower motor resistor. To install, reverse removal procedure.

Scheme 5

Disconnect negative battery cable. Drain cooling system. Raise and support vehicle. Disconnect heater hoses from heater assembly. Plug all openings. Lower vehicle and remove cover from rear heater assembly. Remove vertical and horizontal ducts. Remove top section from heater assembly. Remove combination coil. To install, reverse removal procedure.

1. Disconnect negative battery cable. Drain engine cooling system. In engine compartment, protect generator from coolant spillage.
2. Remove heater hoses from heater core tubes. Plug all openings. Remove grille, cowl grille support panel, right headlight assembly, and right radiator core support assembly. (Scheme 6)
3. From inside vehicle, remove glove box bin. Through glove box opening and from under instrument panel, remove nuts and bolts attaching heater assembly to dash panel.
4. Remove blower housing flange screws. Separate heater assembly from blower housing. (Scheme 4) Carefully remove heater assembly from vehicle.
5. To install, reverse removal procedure. Ensure heater housing top cover seal, firewall and side cowl seals are in good condition.

1. Disconnect negative battery cable. Drain engine cooling system. Disconnect heater hoses from heater assembly. Plug all openings. Remove plumbing plate stud nuts and screw. Lower vehicle and remove cover from rear heater assembly. Remove vertical and horizontal ducts. Remove ground wire.
2. Remove 2 screws securing bottom of rear heater assembly to underbody panel. Lift rear heater assembly until plumbing clears holes in underbody panel. Move assembly away far enough to disconnect harness connector and remove rear heater assembly. To install, reverse removal procedure.

Scheme 6

HEATER CONTROL PANEL R & I

1. Disconnect negative battery cable. Remove engine cover from passenger compartment. Reach between upper dash panel engine housing extension and bottom of instrument panel. Disconnect vacuum harness connector located near left defroster outlet of distribution duct.
2. On models equipped with A/T, unlock ignition switch. Set parking brake and place gear selector lever in "L" position. If equipped, set tilt steering column in lowest position. Carefully pry bezel away from instrument panel to disengage clips. Pull bezel away far enough to clear trip odometer reset button. Remove bezel.
3. Remove 3 screws from heater control panel. Pull heater control panel outward enough to disconnect electrical connectors and vacuum connector. Remove heater control panel. To install, reverse removal procedure.

Remove heater assembly from vehicle. Disable heater assembly and remove heater core. See HEATER ASSEMBLY .

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 7

See also:
• HEATER CONTROL PANEL R & I
• ACCESSORY SWITCH PLATE
• HEATER OUTPUT TEMPERATURE