Volvo Coupes/Sedans/Wagons 1970-1989 Repair Guide

Heater Unit (Complete Assembly)

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REMOVAL & INSTALLATION



1970-72 140 Series and 164

See Figure 1

  1. Remove the lower radiator hose, open the engine drain plug, and drain the cooling system. Disconnect the negative battery cable.
  2.  



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Fig. Fig. 1: Details of the heater unit-1970-72 140 series; 164 models are similar

  1. Remove the hoses to the heater control valve.
  2.  
  3. Remove the heater control panel below the dashboard by removing the two retaining screws. Tilt the top of the panel back so that it loosens from the dashboard clips and clears the hood release.
  4.  
  5. Remove the transmission tunnel mat, defroster hoses, heater control cables, and fan switch wires.
  6.  
  7. Remove the two screws which retain the fuse box to the heater.
  8.  
  9. Remove the control valve, being careful not to damage the copper capillary tube. Loosen the upper hose to the heater.
  10.  
  11. Plug the heater outlets to avoid spilling coolant upon removal. Loosen the heater unit ground cables, remove the four retaining screws, loosen the drain hose, and lift out the heater unit and control valve from their brackets.
  12.  

To install:
  1. Reverse the above procedure to install. Remember to remove all plugs from lines and ports. When reinstalling, support the unit and handle it carefully so the capillary tube is not damaged. Double check the security of all hose clamps and wiring connectors.
  2.  
  3. Carefully refit the control panel and install its screws. Connect the hoses to the heater control valve.
  4.  
  5. Reconnect the negative battery cable and fill the system with coolant.
  6.  

1800 Series
  1. Disconnect the lower radiator hose, open the engine drain plug, and drain the cooling system. Disconnect the negative battery cable.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Disconnect the heater hoses from the heater core pipe and the control valve pipe. Disconnect the fan motor wires.
  2.  
  3. Disconnect the fresh air intake from the heater.
  4.  
  5. On 1970-71 models, remove the pressure regulator bracket retaining screws and allow the pressure regulator to hang free while still connected to the hoses.
  6.  
  7. Remove the four heater-to-firewall attaching nuts.
  8.  
  9. Remove the defroster hoses. Disconnect the heater control valve and the control cables.
  10.  
  11. Lift out the heater and control valve as a unit.
  12.  
  13. Reverse the above procedure to install.
  14.  

1973 140 Series and 164 Models
WITHOUT AIR CONDITIONING
  1. Remove the lower radiator hose, open the engine drain plug, and drain the cooling system. Disconnect the negative battery cable.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the center panel and the left-hand defroster hose.
  2.  
  3. Lift up the driveshaft tunnel mat, disconnect the front and rear attaching screws for the rear seat heater ducts and then remove the ducts.
  4.  
  5. Disconnect the heater control valve and air-mix cables from their shutters.
  6.  
  7. Disconnect and plug the pressure hose at the heater. Also plug the heater pipes to prevent residual coolant from spilling onto the carpet.
  8.  
  9. Remove the attaching screws which secure the left-hand upper bracket to the dashboard and the left-hand lower bracket to the transmission tunnel.
  10.  
  11. Remove the glovebox by unscrewing the four attaching screws, removing the glovebox door stop, and disconnecting the wires from the glovebox courtesy light.
  12.  
  13. Disconnect the defroster and floor heating cables from their levers.
  14.  
  15. Disconnect the fan motor wires at the switch contact plate.
  16.  
  17. Remove the attaching screws which secure the right-hand upper bracket to the dashboard and the right-hand lower bracket to the transmission tunnel.
  18.  
  19. Remove the right-hand defroster hose. Disconnect the hose between the heater and the dashboard circular vents. Lift the heater unit to the right, and then out of the vehicle.
  20.  
  21. Reverse the above procedure to install, taking care to ensure that the air vent rubber seal is properly located, and that the fan motor ground cable is attached at the upper right-hand bracket attaching screw.
  22.  

WITH AIR CONDITIONING

This procedure does NOT require the discharge of the air conditioning system. Do not disconnect any A/C lines or hoses.

  1. Remove the lower radiator hose, open the engine drain plug, and drain the cooling system. Disconnect the negative battery cable.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the heater hoses from the heater pipes at the engine side of the firewall. Plug the heater pipes.
  2.  
  3. Remove the evaporator hose brackets from their body mounts and disconnect the dryer from its bracket. Position the dryer as close to the firewall as the evaporator hose permits. Do not disconnect any air conditioning lines.
  4.  
  5. Remove the instrument cluster by removing the steering column molded casting, removing the bracket retaining screw and lowering it toward the steering column. Remove the four instrument cluster retaining screws, disconnecting the speedometer cable and tilting the speedometer out of its snap fitting. After moving the cluster forward and disconnecting the electrical plug contacts, lift the cluster out of the vehicle.
  6.  
  7. Remove the air hose between the center unit and the left inner air vent. Remove the hose from the vacuum motor for the left defroster nozzle and the left floor outlet (if equipped).
  8.  
  9. Remove the left-side panel from the central unit.
  10.  
  11. Lift up the driveshaft tunnel mat and disconnect the rear seat heater duct from the central unit.
  12.  
  13. Remove the heater pipes from the firewall.
  14.  
  15. Remove the upper and lower attaching screws for the left support leg. Remove the attaching screws which secure the upper bracket to the dashboard and the lower bracket to the transmission tunnel.
  16.  

If the upper bracket screw holes are slotted, the screws need only be slackened a few turns.

  1. Remove the right-side panel from the central unit.
  2.  
  3. Remove the glovebox by unscrewing the four attaching screws, removing the glovebox door stop, and disconnecting the glovebox courtesy light wires.
  4.  
  5. Remove the right defroster nozzle and the air hose between the central unit and the right inner air vent.
  6.  
  7. Lift up the driveshaft tunnel mat and disconnect the rear seat heater duct from the central unit.
  8.  
  9. Remove the upper and lower attaching screws from the right support leg. Remove the lower attaching screws for the control panel.
  10.  
  11. Disconnect the fan motor wires and the ground wires from the control panel.
  12.  
  13. Disconnect the yellow cable from its plug contact.
  14.  
  15. Separate the halves of the vacuum hose connector and disconnect the vacuum tank hose at the connector.
  16.  
  17. Position the control panel as far back on the transmission tunnel as the cables permit.
  18.  
  19. Remove the screws which attach the upper brackets to the firewall and the lower brackets to the transmission tunnel.
  20.  
  21. Remove the thermostat clamp from the central unit, and the two evaporator cover retaining clamps.
  22.  
  23. Without disconnecting any of the refrigerant lines, remove the evaporator from the central unit, placing it on the right-hand side of the firewall.
  24.  
  25. Remove the molded dashboard padding from beneath the glovebox if it's in the way.
  26.  
  27. Remove the retaining clamps for the right outer vent duct, and remove the duct. Pry off the locking retainer for the turbine (blower), and remove the turbine. Remove the clamps which retain the blower housing (inner end) to the central unit and remove the housing.
  28.  
  29. Remove the passenger's front seat (if it's in the way) and lift the central unit forward and onto the floor of the vehicle. Be careful not to place undue stress on the connected refrigerant lines.
  30.  
  31. When reinstalling the central unit,lift it onto the right floor and install the rubber seal for the air intake. Lift the unit into position and insert the upper left bracket over the dashboard screws. Install the right side bracket screws and tighten the left ones.
  32.  
  33. Install the evaporator, cover it and secure the clamps. Carefully reinstall the thermostat on the loser flange.
  34.  
  35. Use a sealing compound around the evaporator pipes and the thermostat line as necessary.
  36.  
  37. Install the ducts for the heater hoses to the dashboard.
  38.  
  39. Install the tunnel brackets and the drain hose.
  40.  
  41. Install the right inner end of the unit and the vacuum hose for the floor shutter.
  42.  
  43. Install the turbine wheel (fan) and the outer end of the central unit. Make sure the clips are reinstalled properly.
  44.  
  45. Install the air duct between the central unit and the right inner air outlet.
  46.  
  47. Install the right defroster nozzle and connect its vacuum hose.
  48.  
  49. Install the glove box, the air duct to the right side vent, and the air ducts to the rear floor.
  50.  
  51. Connect the air duct for the left inner air vent, connect and adjust the left defroster nozzle and attach its vacuum line.
  52.  
  53. Replace the instrument cluster.
  54.  
  55. Reassemble the vacuum connectors and connect the hoses to the vacuum tank.
  56.  
  57. Reconnect the yellow wire to the contact unit and the contact to the control unit.
  58.  
  59. Install the ground wires, tighten the instrument cluster and the support legs.
  60.  
  61. Reinstall the control panel, the insulation pads and the side panels.
  62.  
  63. Connect the heater hoses to the ports on the control unit. Install the firewall panel and clamp down the air conditioning hoses and dryer in the engine compartment.
  64.  
  65. Refill the engine coolant.
  66.  
  67. Double check all installation items, paying particular attention to loose hoses or hanging wires, improperly tightened nuts, poor routing of hoses and wires (too tight or rubbing) and tools left in the area.
  68.  
  69. Reconnect the battery and check the function of the system components.
  70.  

1974 and Later Models Except 700 Series

This procedure does NOT require the discharge of the air conditioning system. Do not disconnect any A/C lines or hoses.

  1. Remove the lower radiator hose, open the engine drain plug, and drain the cooling system. Disconnect the negative battery cable.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the heater hoses from the heater pipes at the engine side of the firewall. Plug the heater pipes.
  2.  
  3. Remove the evaporator hose brackets from their body mounts and disconnect the dryer from its bracket. Position the dryer as close to the firewall as the evaporator hose permits. Do not disconnect any air conditioning lines.
  4.  
  5. Remove the instrument cluster by removing the steering column molded casting, removing the bracket retaining screw and lowering it toward the steering column. Remove the four instrument cluster retaining screws, disconnecting the speedometer cable and tilting the speedometer out of its snap fitting. After moving the cluster forward and disconnecting the electrical plug contacts, lift the cluster out of the vehicle.
  6.  
  7. Remove the air hose between the center unit and the left inner air vent. Remove the hose from the vacuum motor for the left defroster nozzle and the left floor outlet (if equipped).
  8.  
  9. Remove the left-side panel from the central unit.
  10.  
  11. Lift up the driveshaft tunnel mat and disconnect the rear seat heater duct from the central unit.
  12.  
  13. Remove the heater pipes from the firewall.
  14.  
  15. Remove the upper and lower attaching screws for the left support leg. Remove the attaching screws which secure the upper bracket to the dashboard and the lower bracket to the transmission tunnel.
  16.  

If the upper bracket screw holes are slotted, the screws need only be slackened a few turns.

  1. Remove the right-side panel from the central unit.
  2.  
  3. Remove the glovebox by unscrewing the four attaching screws, removing the glovebox door stop, and disconnecting the glovebox courtesy light wires.
  4.  
  5. Remove the right defroster nozzle and the air hose between the central unit and the right inner air vent.
  6.  
  7. Lift up the driveshaft tunnel mat and disconnect the rear seat heater duct from the central unit.
  8.  
  9. Remove the upper and lower attaching screws from the right support leg. Remove the lower attaching screws for the control panel.
  10.  
  11. Disconnect the fan motor wires and the ground wires from the control panel.
  12.  
  13. Disconnect the yellow cable from its plug contact.
  14.  
  15. Separate the halves of the vacuum hose connector and disconnect the vacuum tank hose at the connector.
  16.  
  17. Position the control panel as far back on the transmission tunnel as the cables permit.
  18.  
  19. Remove the screws which attach the upper brackets to the firewall and the lower brackets to the transmission tunnel.
  20.  
  21. Remove the thermostat clamp from the central unit, and the two evaporator cover retaining clamps.
  22.  
  23. Without disconnecting any of the refrigerant lines, remove the evaporator from the central unit, placing it on the right-hand side of the firewall.
  24.  
  25. Remove the molded dashboard padding from beneath the glovebox if it's in the way.
  26.  
  27. Remove the retaining clamps for the right outer vent duct, and remove the duct. Pry off the locking retainer for the turbine (blower), and remove the turbine. Remove the clamps which retain the blower housing (inner end) to the central unit and remove the housing.
  28.  
  29. Remove the passenger's front seat (if it's in the way) and lift the central unit forward and onto the floor of the vehicle. Be careful not to place undue stress on the connected refrigerant lines.
  30.  
  31. When reinstalling the central unit,lift it onto the right floor and install the rubber seal for the air intake. Lift the unit into position and insert the upper left bracket over the dashboard screws. Install the right side bracket screws and tighten the left ones.
  32.  
  33. Install the evaporator, cover it and secure the clamps. Carefully reinstall the thermostat on the loser flange.
  34.  
  35. Use a sealing compound around the evaporator pipes and the thermostat line as necessary.
  36.  
  37. Install the ducts for the heater hoses to the dashboard.
  38.  
  39. Install the tunnel brackets and the drain hose.
  40.  
  41. Install the right inner end of the unit and the vacuum hose for the floor shutter.
  42.  
  43. Install the turbine wheel (fan) and the outer end of the central unit. Make sure the clips are reinstalled properly.
  44.  
  45. Install the air duct between the central unit and the right inner air outlet.
  46.  
  47. Install the right defroster nozzle and connect its vacuum hose.
  48.  
  49. Install the glove box, the air duct to the right side vent, and the air ducts to the rear floor.
  50.  
  51. Connect the air duct for the left inner air vent, connect and adjust the left defroster nozzle and attach its vacuum line.
  52.  
  53. Replace the instrument cluster.
  54.  
  55. Reassemble the vacuum connectors and connect the hoses to the vacuum tank.
  56.  
  57. Reconnect the yellow wire to the contact unit and the contact to the control unit.
  58.  
  59. Install the ground wires, tighten the instrument cluster and the support legs.
  60.  
  61. Reinstall the control panel, the insulation pads and the side panels.
  62.  
  63. Connect the heater hoses to the ports on the control unit. Install the firewall panel and clamp down the air conditioning hoses and dryer in the engine compartment.
  64.  
  65. Refill the engine coolant.
  66.  
  67. Double check all installation items, paying particular attention to loose hoses or hanging wires, improperly tightened nuts, poor routing of hoses and wires (too tight or rubbing) and tools left in the area.
  68.  
  69. Reconnect the battery and check the function of the system components.
  70.  

 
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