Heater System Ford Tempo I

DESCRIPTION

All Ford Motor Co. heater systems are blend air systems. Outside air is drawn into blower housing and is then directed through or around heater core. Hot and cold air is mixed and then discharged through defroster outlets, vent registers or floor ducts.

Discharge air temperature is determined by a temperature blend door, controlled by a lever on control panel. Position of air door determines what portion of incoming air is passed through heater core to be heated. Delivery of discharge air is directed by various doors. Doors may be operated either by a cable or a vacuum motor.

Temperature Lever

Temperature lever is connected by a cable to blend air door. When lever is in "COOL" position, air by-passes heater core. In "WARM" position, air is directed through heater core. In intermediate positions, air is directed both through and around heater core and mixed to produce air of the desired temperature.

Mode Control Lever (Escort)

Mode lever operates heater-defroster door through a control cable.

Mode Control Buttons (Tempo & Topaz)

Mode control buttons operate a vacuum selector switch. Mode control lever interrupts power to blower when in "OFF" position. Buttons control direction of air flow in system by positioning and actuating doors and valves.

Blower Switch (Escort)

Blower switch has "OFF", "HI" and 2 intermediate positions.

Blower Switch (Tempo & Topaz)

Blower switch has a "HI", "LO" and 2 intermediate positions. Blower operates in any mode control position except "OFF".

Thermal Limiter

A thermal limiter resistor assembly is similar to a standard resistor assembly except that an overheating protective device has been added to prevent heat damage to the heater case assembly.

If the temperature of the thermal limiter reaches 250°F (121°C), the contacts in the thermal limiter open. If this occurs, no power will reach the blower motor. The resistor assembly must be replaced if the thermal limiter opens.

Scheme 1

1. Temperature cable and mode control cable self-adjust when levers are moved to end of slots ("WARM" and "DEFROST" positions). Adjustment is required only when a new cable is installed.
2. Pre-set adjustment before self-adjusting the cable. Insert a small screwdriver in loop (crank arm end) of cable and sliding self-adjusting clip so that it is 1" away from loop. (Scheme 1)
3. Install cable, if removed, and move lever to "WARM" or "DEF" position to position self-adjusting clip. Check for proper operation and repeat if necessary.

BLOWER MOTOR VOLTAGE TEST

1. Insert voltmeter probes into wire holes of blower wiring connector and measure voltage drop across motor.
2. With heater on and motor running, voltages should be as specified for each switch position. See «BLOWER MOTOR TEST SPECIFICATIONS»(/ford/tempo/i-1983-1994/remont/heater/#heater-system) table.

BLOWER MOTOR CURRENT DRAW TEST

1. Disconnect blower motor wire connector from blower motor resistor. With a jumper wire and ammeter, connect the ammeter in series with blower motor so blower motor circuit runs through ammeter.
2. Ammeter negative lead should be connected to Orange wire terminal. With heater on and engine running, current draw (amperage) should be as specified for each blower switch position. See «BLOWER MOTOR TEST SPECIFICATIONS»(/ford/tempo/i-1983-1994/remont/heater/#heater-system) table.

BLOWER MOTOR TEST SPECIFICATIONS

Removal & Installation

1. Disconnect battery ground. Drain cooling system. Disconnect heater hoses from heater core and plug openings.
2. Remove sound insulator from underside of instrument panel. Remove 2 screws from steering column cover and remove cover. Remove lower half of steering column shroud. Remove 4 nuts attaching steering column to support bracket and allow steering column to rest on seat.
3. Remove nut attaching instrument panel to steering column support bracket at top of steering column opening. Disconnect center brace from lower flange of instrument panel. Snap out radio speaker opening covers from instrument panel.
4. Remove screws from speakers attaching instrument panel to top of the dash panel. Disconnect speedometer cable from transmission. Disconnect wiring harness connector from blower motor resistor. Disconnect wires from right door courtesy light switch and remove wires from the "A" pillar.
5. Disconnect control cables from heater case. Remove screws attaching each end of instrument panel to the cowl side panels. Pull instrument panel rearward to gain access to heater case and disconnect any wires as necessary.
6. Remove instrument panel center brace from top cowl panel. From engine compartment, remove 2 nuts attaching heater case to dash panel.
7. Loosen sound insulation from top cowl panel around air inlet opening. Pull heater case assembly away from firewall studs and remove heater case from vehicle. To install, reverse removal procedure.

1. Disconnect battery ground. Drain cooling system. Disconnect heater hoses from heater core and plug openings.
2. Remove 2 screws from steering column cover and remove cover. Remove steering column trim shrouds. Disconnect all electrical connections from steering column switches.
3. Remove snap-in lower cluster finish panel(s) to expose 2 screws and 5 bolts. Remove 5 cluster opening finish panel retaining screws and pull panel rearward.
4. Remove 2 retaining bolts on each side of steering column and remove column opening reinforcement. Disconnect speedometer cable at transaxle. Remove 4 screws retaining cluster and carefully pull rearward enough to remove speedometer cable. Loosely install 2 screws to retain cluster during instrument panel removal.
5. Remove one bolt and nut at "U" joint and 4 screws at steering column bracket. Remove steering column. Open glove box and depress sides of bin, allowing stops to move beyond instrument panel walls. Allow glove box door and bin to fall to vertical position.
6. Disconnect all electrical connectors, vacuum hoses, heater control cables and antenna cable. Disconnect all underhood electrical connectors of main wiring harness. Disengage rubber grommet from dash panel and push wire and connectors into instrument panel area.
7. Remove one instrument panel-to-steering column support bracket retaining nut, accessible through steering column opening. Remove one left and one right lower instrument panel-to-cowl side retaining screws.
8. Remove 2 instrument panel vertical brace retaining screws. Remove 4 instrument panel cowl top retaining screws. Remove instrument panel from vehicle.
9. Disconnect connector to blower motor resistor. Remove one screw attaching bottom of heater case to firewall. Remove instrument panel brace from cowl top panel. Remove 2 nuts attaching heater case to firewall in engine compartment.
10. Loosen sound insulation from cowl top panel in area around air inlet opening. Remove 2 screws attaching support bracket and brace to cowl top panel. Pull heater case away from firewall. To install, reverse removal procedure.

1. Drain cooling system. Disconnect heater hoses and plug openings. Remove glove box liner. Move temperature control lever to "WARM" position. Remove heater core cover screws. Remove cover through glove box opening.
2. From inside engine compartment, remove heater case mounting stud nuts. Push heater core tubes and seal toward passenger compartment to loosen core from case. Pull heater core out through glove box area. To install, reverse removal procedure.

1. Drain cooling system. Disconnect heater hoses and plug openings. From inside of vehicle, remove 2 screws retaining floor duct to plenum. Remove 2 screws retaining floor duct to instrument panel. Remove floor duct.
2. Remove 4 screws attaching heater core cover to heater case. Remove heater core cover and heater core from plenum. To install, reverse removal procedure.

Scheme 2

1. Remove right ventilator assembly. Remove hub clamp spring from blower wheel hub and slide blower wheel off blower motor shaft.
2. Remove 3 blower motor flange attaching screws inside blower housing. (Scheme 2) Pull blower motor out of housing and disconnect wiring. To install, reverse removal procedure.

1. Remove contents of glove compartment and remove glove compartment door. Disconnect blower motor wires from blower motor resistor. Loosen instrument panel at lower right side.
2. Remove 4 screws attaching blower motor and mounting plate to heater case. Rotate motor until mounting plate flats clear edge of glove compartment opening. Remove motor and mounting plate from vehicle. To install, reverse removal procedure.

Scheme 3

Scheme 4

1. Move temperature control lever to "COOL" position and mode control lever to "OFF". Disconnect temperature cable self-adjusting clip from temperature door arm.
2. Disconnect temperature cable housing from mounting bracket on heater case assembly with Control Cable Disconnect (T83P-18523-AH). (Scheme 3) Remove screw attaching passenger heater floor duct and remove duct.
3. Disconnect temperature cable from shaft and cable housing bracket on front of heater case assembly. Remove radio control knobs from radio shafts.
4. Remove 2 screws attaching cluster opening finish panel below radio opening. Remove screw attaching finish panel above heater control assembly opening.
5. Remove 2 screws at steering column opening. Remove 3 screws attaching top edge of cluster opening finish panel to instrument panel. Remove finish panel.
6. Remove 4 screws attaching control panel to instrument panel. Pull control panel out from instrument panel. Disconnect wiring harness connectors from control panel. (Scheme 4)
7. Move temperature control lever to "COOL" position. Disconnect temperature cable end retainer from control assembly bracket with Control Cable Disconnect (T83P-18523-AH). (Scheme 3) Disconnect temperature cable from temperature lever.
8. Move mode control lever to "OFF" position. Using Control Cable Disconnect (T83P-18532-AH), disconnect temperature cable end retainer from control assembly bracket. (Scheme 3) Disconnect mode cable from mode lever. To install, reverse removal procedure.

1. Move temperature control lever to "COOL" position. Disconnect temperature cable self-adjusting clip from temperature door arm.
2. Disconnect temperature cable housing from mounting bracket on heater case assembly with Control Cable Disconnect (T83P-18523-AH). (Scheme 3)
3. Insert end of small Phillips screwdriver into 9/64" (3.5 mm) holes in control panel bezel. Apply a light inward force to heater control assembly. Spring clip will become depressed, releasing heater control from register housing.
4. Pull control assembly out of register housing and disconnect wire harness connectors from control assembly. Move temperature selector lever to end of slot (COOL) and disconnect temperature cable end retainer from control assembly bracket.
5. Remove twist-off cap from temperature control lever and remove temperature control cable. To install, reverse removal procedure.

Scheme 5

See also:
• BLOWER MOTOR TEST SPECIFICATIONS