Cooling, heating and ventilation systems FIAT PUNTO 1994 176 / 1.G Workshop Manual

Contents
REPAIRS AND OVERHAUL
Engine and associated systems SOHC (8-valve) petrol engine in-car repair procedures Page 2A«1 DOHC (16-valve) petrol engine in-car repair procedures Page 2B«1 Diesel engine in-car repair procedures Page 2C«1 Engine removal and overhaul procedures Page 2D«1 Cooling, heating and ventilation systems Page 3»1 Fuel system - single-point petrol injection models Page 4A«1 Fuel system - multi-point petrol injection models Page 4B«1 Fuel system - diesel models Page 4C»1 Exhaust and emission control systems Page 4D*1 Starting and charging systems Page SA«1 Ignition system - petrol models Page SB«1 Preheating system - diesel models Page 5C>1
Transmission Clutch Page 6»1 Manual transmission Page 7A«1 Automatic transmission Page 7B*1 Driveshafts Page 8*1
Brakes and suspension Braking system Page 9*1 Suspension and steering Page 10-1
Body equipment Bodywork, trim and Fittings Page 11«1 Body electrical systems Page 12*1
Wiring diagrams Page 12»13
REFERENCE
Dimensions and weights Page REF«1 Conversion factors Page REF*2 Buying spare parts Page REF»3 Vehicle identification Page REF«3 General repair procedures Page REF«4 Jacking and vehicle support Page REF»5 Disconnecting the battery Page REF«5 Tools and working facilities Page REF-6 MOT test checks Page REF»8 Fault finding Page REF»12 Glossary of technical terms Page REF»20
index Page REF»24
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3*1
Chapter 3
Cooling, heating and ventilation systems
Contents
Air conditioning system - general Information and precautions .... 9 Mr conditioning system components * removal and refitting 10 Antifreeze mixture See Chapter 1A or 1B Auxiliary drivebell(s) check and renewal See Chapter 1A or IB Coolant level check See Weekly checks Coolant pump - removal, Inspection and refitting 7 Coolant renewal See Chapter 1A or 1B
Degrees of difficulty
Cooling fan switch - testing, removal and refitting 6 Cooling system hoses • disconnection and renewal 2 Electric cooling fan(s) - testing, removal and refitting 5 General information and precautions 1 Heater/ventilation components • removal and refitting 8 Radiator - removal, inspection and refitting 3 Thermostat - removal, testing and refitting 4

Easy,
suitable foe JS^, novice
with
little experience ^
Fairly
easy,
sutable for beginner witti
some experience
^
Faiilydifltctit,
suitable
for competent
DIY mechanic
^

Difficult,
sutable for & experienced DIY « mechanic ^
VerydMlcult, ^
suitable
for
expert DIY
« or professional
Specifications
General Expansion tank relief valve opening pressure 0.96 bar Coolant pump Impeller-to-casing clearance: Diesel engine models 0.53 to 1.37 mm Petrol engine models 0.4 to 0.9 mm
Thermostat Diesel engine models: Opening temperature: Starts to open 78 to 82*0 Fully open 88°C Maximum valve travel (approximate) 7.5 mm Petrol engine models: Opening temperature: 1108 cc and 1242 cc (8-valve) engines: Starts to open 85 to 89°C Fully open 100°C 1242 cc (16-valve) engines: Starts to open 81 to 85°C Fully open 103°C Maximum valve lift (approximate) 7.5 mm
Electric cooling fan Petrol engine models with single speed fan: Cut-in temperature 90to94°C Cut-out temperature B5 to 89°C Diesel engine models with twin speed fan: Cut-In temperature: Primary fan 86 to 90® C Secondary fan 90 to 94°C Cut-out temperature: Primary fan 81to85°C Secondary fan 85 to 89°C
Torque wrench settings Nm tbfft Coolant pump pulley securing bolts (diesel engine models) 23 17 Coolant pump securing bolts: Diesel engine models 23 17 Petrol engine models 8 6 Coolant pump securing nuts (petrol engine models) 10 7

3*2 Cooling, heating and ventilation systems
1 General information and precautions
Genera/ Information The engine cooling/cabin heating system is ol pressurised type, comprising a coolant pump driven by the camshaft timing belt (petrol engine models) or auxiliary drlvebelt (diesel engine models), a crossllow radiator, a coolant expansion tank, an electric cooling fan, a thermostat, heater matrix, and all associated hoses and switches. The system functions as follows: Ihe coolant pump circulates cold water around the cylinder block and head passages, and through the Inlet manifold, heater matrix and throttle body to the thermostat housing. When the engine Is cold, the thermostat remains closed and prevents coolant from circulating through the radiator. When the coolant reaches a predetermined temperature, the thermostat opens, and the coolant passes through the top hose to the radiator. As the coolant circulates through the radiator, it is cooled by the in-rush of air when the car is in forward motion. The airllow is supplemented by the action of the electric cooling fan. when necessary, As the temperature of the coolant in the radiator drops, it flows to the bottom of the radiator by convection, and passes out through the bottom hose to the coolant pump - the cycle is then repeatod, When the engine is at normal operating temperature, the coolant expands, and some of It is displaced into the expansion tank. Coolant collects In the tank, and ts returned to Ihe radiator when the system cools. On petrol engine models, the expansion tank is integrated into the side of the radiator. On diesel engine models, and certain petrol engine models with air conditioning, the tank is a separate unit, mounted on the right hand side of the engine compartment. On turbo diesel engine models, the coolant is also passed through a supplementary engine oil cooler, to assist In controlling the engine lubricant temperature. Tho electric cooling fan mounted in front of the radiator is controlled by a thermostatic switch. At a predetermined coolant temperature, the swilch/sensor actuates the tan lo provide additional airflow through the radiator, The switch cuts the electrical supply to the Ion when the coolant temperature has dropped below a preset threshold (see Specifications).
Precautions

A


Warning: Do not attempt to remove the expansion tank pressure cap, or to disturb any part of the cooling system, whlio the engine is hot, as then is a high risk of scalding, tf the expansion tank pressure cap must be removed before the
engine and radiator have fulty cooled (even though this is not recommended?, the pressure in the cooling system must first be relieved. Cover the cap with a thick layer of cloth, to avoid scalding, and slowly unscrew the pressuro cap until a hissing sound Is heard. When the hissing stops, indicating that the pressure has reduced, slowly unscrew the pressure cap until it can be removed; If more hissing sounds are heard, wait until they have stopped before unscrewing the cap completely. At all times, keep your face well away from the pressure cap opening, and protect your hands.

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Warning: Do not allow antifreeze to come into contact with your skin, or with the painted surfaces of the vehicle. Rinse off spills immediately, with plenty of water. Never leave antifreeze lying around in an open container, or In a puddle In the driveway or on the garage floor. Children and pets are attracted by its sweet smell, but antifreeze can be fatal tf ingested.

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Warning: If the engine is hot, the electric cooling fan may start rotating even if the engine and ignition are switched off. Be careful to keep your hands, hair, and any loose clothing well clear when working In the engine compartment.
2 Cooling system hoses - f&> disconnection and renewal ^
1 The number, routing and pattern of hoses will vary according to model, but the same basic procedure applies. Before commencing work, make sure that the new hoses are to hand, along wilh new hose clips if needed, it is good practice to renew the hose clips at the same time as the hoses. 2 Drain the cooling system, as described in Chapter 1A or 18, saving the coolant if it is fit for re-use. Apply a little penetrating oil onto the hose clips if they are corroded. 3 Release the hose clips from the hose concerned. Three types of clip are used; worm-drive. spring and 'sardine-can'. The worm-drive clip is released by turning its screw anti-clockwise. The spring clip Is released by squeezing Its tags together with pliers, at the same time working the cbp away from the hose stub. The sardine-can clips are not re-usable, and are best cut off with snips or side cutters. 4 Unclip any wires, cables or other hoses which may be attached to the hose being removed. Make notes for reference when reassembling If necessary. 5 Release the hose from its stubs with a twisting motion. Be careful not to damage the stubs on deltcate components such as the radiator, or thermostat housings. If the hose Is stuck fast, the best course is often to cut it off using a sharp knife, but again be careful not to damage the stubs.
6 Before fitting the new hose, smear the stubs with washing-up liquid or a suitable rubber lubricant to aid fitting. Do not use oil or grease, which may attack the rubber. 7 Fit the hose clips over the ends of the hose, then fit the hose over its stubs. Work the hose Into position. When satisfied, locate and tighten the hose dips. 6 Refill the cooling system as described In Chapter 1A or 1B. Run the engine, and chock that there are no leaks. 9 Recheck the tightness of Ihe hose clips on any new hoses after a few hundred miles. 10 Top-up the coolant level if necessary.
3 Radiator -
removal,
inspection and refitting
Removal Note: If leakage is the reason for removing
the
radiator, bear In mind that minor leaks can often be cured using proprietary radiator sealing compound, with the radiator in situ. 1 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual). On diesel engine models, unbolt the relay bracket from the side of the battery tray. 2 Drain the cooling system as described In Chapter 1A or 1B. 3 On 1242 cc (16-valve) petrol engine models, remove the air cleaner and Inlet ducts as desenbed In Chapter 4B, 4 Slacken the clips and disconnect Ihe (op and bottom coolant hoses from the radiator. In addition on diesel engine models, and petrol engine models with a remotely-sited expansion tank, disconnect the expansion tank coolant hose from the right hand side ol the radiator (see Illustrations), 5 Unscrew the fixings and lift the plastic trim panel from above the front bumper Unscrew the bolt(s) securing tho radiator to the upper body panel (see Illustration). Note that the radiator and cooling fan assembly share the same upper mounting bolt. 6 Unbolt the cooling fan(e) and shroud assembly from Ihe rear ot the radiator, as described in Section 5.
3.4a Slacken the clip and disconnect the radiator bottom hose

3*2 Cooling, heating and ventilation systems
3.4b On diesel engine models, disconnect the expansion tank coolant hose from the radiator 3.5 Unscrew the bolts securing the radiator to the uppor body panel
3.8 Disengage the lower mountings studs from the onglne compartment lower crossmember
4.6a Removing the thermostat housing (petrol engine) 4.6b Thermostat housing location - Ignition distributor removed for clarity (petrol engine) ? Withdraw the mounting brackets (where applicable), and recover the upper mounting rubbers. 8 Carefully tilt the radiator back towards the engine, then disengage the lower mountings studs from the crossmember and lift the radiator from the engine compartment (see illustration). Recover the lower mounting rubbers if they are loose. Inspect/on 9II the radiator has been removed due to suspected blockage, it may be flushed out as descnbed in Chapter lAor 10. Clean dirt and debris from the radiator fins, using an air line fn which case, wear eye protection) or a soft Brush. Be careful, as the fins are sharp, and
can
also be easily damaged. ID If necessary, a radiator specialist can perform a flow test on the radiator, to establish whether an internal blockage exists. 11 A leaking radiator must be referred to a specialist for permanent repair. Do not attempt to weld or solder a leaking radiator, as damage to the plastic components may result. Note: In
an emergency,
minor
leaks
from the radiator can often be cured by using a suitable radiator seat'ng compound, in accordance with its manu-
facturer's
instructions, with the radiator in situ. 12 If the radiator is to be sent for repair or is
to
be renewed, remove all hoses (and where
applicable, the cooling fan switch). 13 Inspect Ihe radiator mounting rubbers, and renew them if necessary. Refitting 14 Refitting is a reversal of removal, bearing in mind the following points: a) Ensure that the radiator lower lugs engage correctly with the lower mounting rubbers. b) On completion, refill the cooling system as described in Chapter 1A or IB.
Thermostat - Jk removal, testing and refitting #
General 1 The thermostat housing Is bolted to the left hand end of the cylinder head. The thermostat itself cannot be separated from the housing and can only be renewed as part of a complete assembly.
Removal 2 Drain the cooling system as described in Chapter 1A or 1B. 3 On diesel engine models, unbolt the wiring harness/fuel hose support bracket from the housing. On 1242 cc (16-valve) petrol engine
models, remove the air cleaner and inlet ducts as descnbed in Chapter 4B. 4 Slacken the clipfs) and detach the coolant hose(s) from the thermostai housing, Make a careful note of their orientation to aid refitting. 5 Where applicable, disconnect the wiring plug from the cooling fan switch and coolant temperature sensor, which are threaded into the thermostat cover. 6 Unscrew the securing bolts, and remove the thermostat housing from the cylinder head (see illustrations). If it sticks, tap it gently first on one side and then the other to free it - do not lever between the mating faces. Recover the remains of the old c,
4.6c Removing the thermostat housing (diesel engine)

3*2 Cooling, heating and ventilation systems
Testing 7 A rough test of the thermostat may be made by suspending it with a piece of siring in a container full of water. Heat tho water to bring it to the boii and observe the movement of the vaive shaft through the inlet port (see illustrations). 6 The thermostat valve must be fully open, by the time the water boils. If not, renew the complete IhermOstat/housIng assembly. 9 If a thermometer is available, the precise opening temperature of the thermostat may be determined; compare with the figures given in the Specifications. The opening temperature Is also marked on the thermostat housing. 10 Note that a thermostat which falls to close completely as ihe water cools must also be renewed.
Refitting 11 Ensure that the cylinder head and thermostat housing mating surfaces are
completely clean and free from ail traces of Ihe old gasket material. 12 Lay a new gasket In position on the cylinder head, then fit the thermostat housing and Insert retaining bolts, tightening them securely.
Caution: Do not over-tlghten tho retaining bolts, as tho alloy casting could easily be damaged 13 Where applicable, transfer the cooling fan switch and coolant temperature sensor to the new housing. 14 Refit the coolant hose(s) to the ports on the thermostat housing and lighten the clips securely. 15 Where applicable, refit the harness/hose support bracket to the thermostat housing and tighten the bolts securely. Also refit the air cleaner and Inlet ducts as described in Chapter 4B 15 Refill the cooling system as described in Chapter 1A or 1B.
5 Electric cooling fan(s) -testing, removal and refitting ^
Testing 1 Detailed fault diagnosis should be camw out by a Rat dealer using dedicated tesl equipment, but basic diagnosis can be car&c out as follows. 2 If the fan does not appear to work, run if* engine until normal operating temperature s reached, Ihen allow It to idle. The fan shouldcti In within a few minutes (before lite temperalure gauge needle enters the red section), il nol. switch off the engine and disconnect tfie cooling fan motor wiring connector. 3 The motor can be tested by disconnecting it from the wiring loom, and connecting a 12? volt supply directly to It. The motor should operate - if not. the motor, or the motor wiring. Is faulty.
frotf heater from cylinder head mdotor
4.7b Thermostat operation in the fully closed position (diesel engine)
from neoier Irom cylinder head radiator
4.7c Thermostat operation in the fully open position (diesel engine)

3*2 Cooling, heating and ventilation systems
4 If the motor operates when tested as described, (he fault must lie In the engine wring harness or the temperature sensor. The temperature sensor/switch can be tested as described in Section 6. Any further fault Diagnosis should be referred to a suitably-equipped Fiat dealer - do not attempt to test
Ihe
electronic control unit.
Removal 5 Disconnect the battery negative terminal (refer to D/scon oecf/ng the battery in the Reference Section of this manual). 6 On diesel engine models, unbolt the relay bracket from the side of the battery tray to improve access. On 1242 cc {16-valve) petrol engine models, remove the air cleaner and
inset
ducts as described in Chapter 4B. 1 Disconnect the motor wiring connectorfs). 8 Unbolt the shroud from the rear of the ratiator. then lift out the cooling fan assembly. Refitting 9 Refitting is a reversal of removal
6 Cooling fan switch -testing, removal and refitting ^
Testing 1 The switch is threaded into the lower left
nand
comer of the radiator. 2 The switch can be tested by removing it,
and
checking that the switching action occurs
at
the correct temperature {heat the sensor in a container of water, and monitor the temperature with a thermometer). 3 There should be no continuity between the switch terminals, until Ihe specified cooling fan cut-In temperature Is reached, when continuity (and zero resistance) should exist between the terminals.
Removal 4 Disconnect the battery negative terminal refer to Disconnecting the battery in the Reference Section of this manual). 5 Allow the engine to cool completely, then drain the cooling system as described in Chapter 1Aor 1B. 6 Disconnect the wiring plug from the sensor.
bolts...
7 Carefully unscrew the sensor and. whore applicable, recover the sealing ring. Refitting 8 If the sensor was originally fitted using sealing compound, clean the sensor threads thoroughly, and coat them with fresh sealing compound. 9 If the sensor was originally fitted using a sealing ring, use a new sealing ring on refitting. 10 Refitting is a reversal of removal, but refill the cooling system as described in Chapter 1A or 18. 11 On completion, start the engine and run it until it reaches normal operating temperature. Continue to run the engine until the cooling fan cuts in and out correctly.
7 Coolant pump • & removal, inspection 5 and refitting
Removal
Petrol engine models 1 Disconnect the battery negative terminal (refer to Disconnecting the battery in the Reference Section of this manual). 2 Drain the cooling system and remove the auxiliary drivebett(s) as described In Chapter 1 A. 3 Remove the timing belt as described In Chapter 2A or 28. 4 Unscrew the securing bolts/nuts, and withdraw the coolant pump (see illustrations).
7.9b ... and lift off the pulley (diesel engine)
(petrol engine) If the pump Is stuck, tap it gently using a soft-faced mallet - do not lever between the pump and cylinder block mating faces.
Diesel engine models 5 Disconnect the battery negative terminal (refer to D/s connecting the battery in the Reference Section of this manual). 6 Drain the cooling system as described in Chapter 1B. 7 Remove the auxiliary drivebelt(s) as descnbed In Chapter 1B. 6 On models fitted with power steenng, refer to Chapter 10 and remove the power steering pump from its mountings; this can be achieved without disconnecting the power steering fluid hoses from the pump. Tie the pump away from the work area, taking care to avoid kinking the fluid hoses. 9 Unscrew the securing bolts, and remove the coolant pump pulley. It will be necessary to counterhold the pulley In order to unscrew the bolts, and this is most easily achieved by wrapping an old drivebelt tightly around the pulley to act in a similar manner to a strap 3 wrench. Alternatively, a stout screwdriver can be braced between two of the pulley bolts while the third is slackened (see illustrations). 10 Disconnect ihe bypass hoses from the coolant pump outlet stubs. 11 Unscrew the securing bolts, and withdraw the coolant pump assembly. Note that the pump must be detached from the transfer pipe than runs behind the cylinder block to the thermostat housing (see illustration). The pipe is a push fit in the port on the rear of the coolant pump
7.11 Removing the coolant pump assembly (diesel engine)

3*2 Cooling, heating and ventilation systems
12 If tho pump is stuck, tap It gently using a soft-faced mallet • do not lever between the pump and cylinder block mating faces.
Inspection 13 Check the pump body and impeller for signs of excessive corrosion. Turn the impeller, and check for stiffness due to corrosion, or roughness due to excessive end play. 14 Check the clearance between the pump Impeller and the casing using a feeler blade (see Illustration). If the clearance is different to that given In the Specifications, the pump must be renewed. No spare components are available; the pump can only be renewed as a complete assembly. 15 On diesel engine models, remove the O-rlng at the end ol the transfer pipe, which runs behind Ihe cylinder block and fits Into the rear of the coolant pump. A new O-rlng should be fitted as a matter of course.
Refitting
Petrol engine models 16 Commence refitting by thoroughly cleaning all traces of sealant from the mating faces of the pump and cylinder block/pump housing. 17 Apply a continuous bead of sealant {liquid gasket) to the cylinder block mating face of the pump, taking care not to apply excessive sealant, which may enter the pump itself (see Illustration). 18 Place the pump In position In Its housing, then refit and lighten the bolts/nuts to the specified torque. 19 Refit the liming belt as described In Chapter 2A or 28. 20 Refit the auxiliary drivebeltfs) and refill the cooling system as described in Chapter
t
A. 21 Reconnect Ihe battery negative terminal. Diesel engine models 22 Commence refitting by thoroughly cleaning all traces of old gasket from the mating faces of the pump housing and cylinder block. 23 Place a new gasket in position on (he cylinder block, locate the pump in position, then refit and tighten the bolts (see
7.17 On petrol engine models, apply a continuous bead of sealant (liquid gasket) to the pump mating face
pump Impeller and the casing using a feeler blode (diesel engine) illustration). Ensure that the end of the coolant transfer pipe seats firmly In tho port at the rear of the coolant pump, without displacing the O-ring seal. 24 Refit Ihe pump pulley, then refit the securing bolts and tighten to the specified torque. Counterhofd the pulley using the same method employed during removal. 25 Where applicable, refit the power steering pump with reference to Chapter 10. 26 Refit and tension the auxiliary drivebelt(s) as described in Chapter 18. 27 Refill (he cooling system as desenbed in Chapter 1B. 28 Reconnect the battery negative terminal.
8 Heater/ventilation components - § removal and refitting
Complete heater assembly

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Warning: On mode's fitted with air conditioning, do not attempt to remove the cooling unit, which Is located between the heater blower motor casing and the main heater assembly. Romovat of the cooling unit entails disconnection of refrigerant lines - refer to Section 10 for precautions to be observed.
rfJS
<v 7.23 On diesel engine models, place a new gasket In position on the cylinder block
tf In any doubt as to the procedure fo follow on models with air conditioning, consult a Fiat dealer for advice. Note: This is an involved procedure, and It (s recommended fhat the following Section fs read thoroughly before commencing work. Plenty of time should be allowed to compter the operation. During dismantling, make notes on the routing of all wiring and cables, and the locations of all fixings, to aid reassembly. Removal 1 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual), 2 Set the heater control to HOT. then drain the cooling system as described In Chapter 1A or 18. 3 Working in the engine bay, slacken the clips and dotach the healer unit coolant hoses from the ports at the bulkhead (see illustration) Recover the rubber grommets. 4 Refer to Chapter 11 and remove the entire facia assembly from the vehicle bulkhead. Rest the assembly on the front seats. 5 At this stage, access to the air l nlet/dlstrl but Ion/blending control cables is possible. These can be easily disconnected from their respective control levers and renewed If required. 6 Working from the engine bay. remove the protective plastic caps to expose the heater assembty mounting studs and remove the nuts 7 Label the electrical connections to 1hi» heater assembly, to aid correct refitting later and then unplug them at the connectors 8 Slacken and remove the nuts and lift the healer assembly off its mounting studs. Refitting 9 To refit the assembly, reverse the steps described for removal, bearing in mind the following points: a) Make sure that all wiring and cables are muted as noted during dismantling. b) Make sure that dl air ducts are securely reconnected. c) Refit the facia components with reference to Chapter 11. dl On completion, refill the cooling system as described In Chapter 1A or 18.
8.3 Slacken the clips (arrowed) and detach the heater unit coolant hoses from the ports at the bulkhead

3*2 Cooling, heating and ventilation systems
Heater matrix Removal 10 Remove the complete heater assembly as described previously in this Section. 11 Slacken and remove the securing screws, then withdraw the heater matrix from the tester assembly casing. Refitting 12 Refitting is a reversal of removal; refit Ihe neater assembly as described previously in
this
Section.
Heater blower motor
Removal 13 Disconnect the battery negative terminal {refer to Disconnecting the battery in the Reference Section of this manual). 14 Unplug the wiring from the blower motor
al the
connector. 15 Working in the passenger front footwell, under the glovebox. remove the securing grows and lower the blower motor and rotor assembly from Its casing (see illustration). Refitting
16 Refitting is a reversal of removal.
Heater blower motor resistor
Removal 17 The resistor is located at the bottom of the heater casing, behind the blower motor. 18 Disconnect the battery negative terminal (refer to O/sconnecf/ng the battery in the Reference Section of this manual). 19 For improved access, remove the blower motor as described in the previous sub-Section. 20 Disconnect the wiring plug from the resistor. 21 Working under the glovebox. remove the two securing screws, and withdraw the resistor from the blower unit case (see lustrations).
8.15 Removo the securing screws and lower the blower motor and rotor assembly from its casing Refitting 22 Refining Is a reversal of removal.
Heater control panel
Removal 23 Pull the ventilation fan speed control knob from the panel. 24 Unscrew and remove the three screws securing the panel cover. Two screws are under the lower edge of the panel, whilst Ihe remaining screw is located in the ventilation fan speed control knob recess. Remove the panel. 25 Unscrew and remove the four screws securing the control panel to the facia. The screws are located in each comer of the panel. 26 Remove the facia as described in Chap-ter 11. 27 Make a careful note of the cable and electrical connections. Unscrew the cable clamps and unclip the inner cables from the controls. Unplug the ventilation fan speed control. 28 Unclip and remove the control panel from the heater distributor box assembly. Refitting 29 Refitting is a reversal of removal.
9 Air conditioning system -general Information and precautions
General information An air conditioning system is available on certain models. It enables the temperature of Incoming air to be lowered, and also dehumidifies the air, which allows rapid demisting and increased comfort. The cooling side of the system works In the same way as a domestic refrigerator. Refrigerant gas is drawn into a belt-driven compressor where the increase In pressure causes the refrigerant gas to turn to liquid. It then passes through a condenser mounted on the front of the radiator, where it is cooled. Tho liquid then passes through an expansion vaive to an evaporator, where it changes from liquid under high pressure to gas under low pressure. This change is accompanied by a drop in temperature, which cools the evaporator and hence the air passing over it. The refrigerant returns to the compressor, and the cycle begins again. The air bfown through the evaporator passes to the air distribution unit where it is mixed, if required, with hot air blown through the heater matrix to achieve the desired temperature in the passenger compartment. The heating side of ihe system works in the same way as on models without air conditioning (see Section 8). The system Is electronically-controlled. Any problems with the system should be referred to a Fiat dealer.
Precautions With an air conditioning system. It is necessary to observe special precautions whenever dealing with any part of the system, or its associated components. If for any reason the system must be disconnected, it Is
8.21a Remove the two securing screws (arrowed)... ,21b ... and withdraw the resistor from the blower unit case

3*2 Cooling, heating and ventilation systems
essential that you entrust this task to your Flat dealer or a refrlgeralion engineer.

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Warning: The refrigeration circuit contains a liquid refrigerant and
H
Is dangerous to disconnect any part of the system without specialist knowledge and equipment. The refrigerant is potentially dangerous, and should only be handled by qualified persons. If it is splashed onto tha skin, It can cause severe frostbite, tt Is not Itself poisonous, but In the presence of a naked flame (Including a cigarette), it forms a
poisonous gas. Uncontrolled discharging of the refrigerant is dangerous and potentially damaging to the environment.
10 Air conditioning components ^S - removal and refitting J
Note: Do not operate the air conditioning system If it is known to be short of refrigerant, as this may damage the compressor. 1 The only operation which can be carried
out easily without discharging the refrigerant is renewal of the auxiliary (compressor) drivebelt - this procedure Is described in Chapter 1A or 1B. All other operations must be referred to a Fiat dealer or an air conditioning specialist. 2 If necessary for access to other com-ponents, the compressor can be unbolted and moved aside, without disconnecting its flexible hoses, after removing the drivebelt.

A


Warning: Do not attempt to open the refrigerant circuit. Refer to
the
precautions given in Section 9.
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