check engine FORD SIERRA 1991 2.G Cooling And Air Conditioning Systems Workshop Manual

passing over the evaporator fins on its way to
the vehicle interior. The refrigerant becomes a
gas again and the cycle is repeated.
Various subsidiary controls and sensors
protect the system against excessive
temperature and pressures. Additionally,
engine idle speed is increased when the
system is in use to compensate for the
additional load imposed by the compressor.
Precautions
Air conditioning refrigerant
Although the refrigerant is not itself toxic, in
the presence of a naked flame (or a lighted
cigarette) it forms a highly toxic gas. Liquid
refrigerant spilled on the skin will cause
frostbite. If refrigerant enters the eyes, rinse
them with a dilute solution of boric acid and
seek medical advice immediately.
In view of the above points, and of the need
for specialised equipment for evacuating and
recharging the system, any work which
requires the disconnection of a refrigerant line
must be left to a specialist.
Do not allow refrigerant lines to be exposed
to temperatures above 230°F (110°C) - eg
during welding or paint drying operations and
do not operate the air conditioning system if it
is known to be short of refrigerant, or further
damage may result.
Antifreeze mixture
Antifreeze mixture is poisonous. Keep it out
of reach of children and pets. Wash splashes
off skin and clothing with plenty of water.
Wash splashes off vehicle paintwork to avoid
discolouration.
Antifreeze/water mixture must be renewed
at the specified intervals to preserve its anti-
corrosive properties. In climates where
antifreeze protection is unnecessary, a
corrosion inhibitor may be used instead -
consult a Ford dealer. Never run the engine
for long periods with plain water as coolant.
Only use the specified antifreeze as inferior
brands may not contain the necessary
corrosion inhibitors, or may break down at
high temperatures. Antifreeze containing
methanol is particularly to be avoided, as the
methanol evaporates.
The specified mixture is 45 to 50%
antifreeze and 50 to 55% clean soft water (by
volume). Mix the required quantity in a clean
container.
Refer to Chapter 1, Section 46.
Refer to Chapter 1, Section 46.
Refer to Chapter 1, Section 46.
Removal
1Disconnect the battery negative lead.
2Drain the cooling system.
3If not already done, disconnect the bottom
hose from the radiator.
4Disconnect the top hose and the expansion
tank hose from the radiator.
5On automatic transmission models, place a
suitable container beneath the fluid cooler
pipe connections at the radiator. Unscrew the
union and plug the upper pipe, then repeat
the procedure on the lower pipe.
6Apply the handbrake, jack up the front of
the vehicle and support on axle stands (see
“Jacking and Vehicle Support”).
7To improve access, remove the cooling fan
shroud as follows, according to model.
8On SOHC models, remove the four
retaining clips and unscrew the two retaining
screws, then withdraw the upper section of
the fan shroud. Unclip and remove the lower
section of the shroud.
9On CVH and DOHC models, unclip the
wiring connector from the fan motor(s) then
unscrew the retaining nuts and washers, and
withdraw the fan shroud(s) and cooling fan
assembly(s) (see illustration).
10On early models, unscrew and remove the
upper radiator mounting nuts and washers
(see illustration). Unscrew and remove the
lower mounting bolts and washers and
withdraw the radiator from under the vehicle
(see illustration).11On all later models, the radiator is secured
to the engine compartment front panel using
clips and locking pegs. To release the top of
the radiator, work through the cut-outs in the
engine compartment front panel and remove
the two radiator upper locking pegs (see
illustration). Working under the front of the
vehicle, remove the two radiator lower
mounting bolts. Support the radiator from
underneath. Squeeze the upper radiator
locking pegs to release them from the engine
compartment front panel and lower the
radiator assembly from the vehicle.
Refitting
12Refitting is a reversal of removal, bearing
in mind the following points.
13Refill the cooling system.
14On automatic transmission models, check
and if necessary top-up the transmission fluid
level.
1If the radiator has been removed because
of suspected blockage, reverse-flush it.
2Clean dirt and debris from the radiator fins
using an air jet or water and a soft brush. Be
careful not to damage the fins or cut your
fingers.
6Radiator -inspectionand
cleaning
5Radiator - removal and refitting
4Cooling system - filling
3Cooling system - flushing
2Cooling system - draining
Cooling, heating and air conditioning systems 3•3
3
5.10a Radiator and cooling fan shroud
upper mountings
A Radiator mounting nut
B Shroud securing screw
C Shroud securing clips
D Radiator top hose clip
5.11Removing a radiator upper locking peg5.10b Lower radiator mounting bolt
5.9 Unscrew the fan shroud/radiator
retaining nuts

36Tighten the coolant pump securing bolts,
and where applicable the pump pulley
securing bolts, to the specified torque.
37On completion, refill the cooling system.
Refer to Chapter 1, Section 21.
Removal
1Remove the alternator drivebelt.
2Loosen the alternator lower mounting
through-bolt, then remove the alternator
upper mounting bolt and swing the alternator
away from the engine.
3Unscrew the central securing bolt, and
withdraw the drivebelt tensioner assembly
(see illustration).
Refitting
4Commence refitting by positioning the
tensioner on the cylinder block, ensuring that
the lug on the rear of the tensioner bracket
engages with the corresponding hole in the
cylinder block. Tighten the securing bolt.
5Swing the alternator into position, to align
the upper mounting bolt hole with the
corresponding hole in the drivebelt tensionerassembly. Refit the upper mounting bolt, and
tighten the upper bolt and lower through-bolt.
6Fit the drivebelt by reversing the removal
procedure, and release the tensioner to
tension the drivebelt.
7Observe the tensioner indicator, which
should be central in its slot (see illustration).
Removal
1Disconnect the battery negative lead.
2Remove the four retaining clips and
unscrew the two retaining screws, then
withdraw the upper section of the fan shroud
(see illustrations).
3The cooling fan hub nut must now be
unscrewed from the coolant pump drive
flange. A thin cranked 32.0 mm (1.25 in AF)
spanner with a jaw thickness not exceeding
5.0 mm (0.2 in) will be required (see
illustration). Alternatively, if two of the
coolant pump pulley bolts are removed, a
normal thickness spanner can be used.Note
that the fan hub nut has a left-hand thread, (ie
it is undone in a clockwise direction.) If the
pulley turns as the nut is undone, remove the
drivebelt, and clamp an old drivebelt round
the pulley to restrain it, using self-locking
pliers. Tap the spanner with a mallet if
required to remove the nut.4If required, the fan blades can be separated
from the fan hub by unscrewing the four
securing bolts.
Refitting
5Refitting is a reversal of removal, but where
applicable, take care not to overtighten the
bolts securing the fan blades to the fan hub,
as thread damage may require the whole unit
to be renewed. Where applicable, refit and
tension the drivebelt.
CVH models
1Disconnect the battery negative lead.
Unclip the wiring connector from the fan
motor then unscrew the retaining nuts and
washers. Withdraw the fan shroud and
cooling fan assembly (see illustration).
2To remove the fan blades, prise the
securing clip from the end of the motor shaft
(see illustration).
3The motor can be separated from the fan
shroud by unscrewing the three securing nuts
and bolts.
4Where two cooling fans are fitted, both fans
are secured to the fan shroud in the same
manner.
5Refitting is a reversal of removal, but when
refitting the fan blades, ensure that the
direction of rotation arrow faces away from
the motor, towards the radiator.
13Electric cooling fan -removal
andrefitting
12Thermo-viscous cooling fan
(SOHC models) - removal and
refitting
11Coolant pump/alternator
drivebelt tensioner (DOHC
models with power steering)
- removal and refitting
10Coolant pump/alternator
drivebelt(s) - checking, renewal
and tensioning
Cooling, heating and air conditioning systems 3•7
3
12.2a Remove the retaining clips followed
by the screws . . .
13.1 Withdrawing the fan shroud and
cooling fan assembly
12.3 Modified spanner required for
removing the thermo-viscous cooling fan
X = 25.0 mm (1.0 in)Y = 12.0 mm (0.5 in)12.2b . . . and withdraw the upper section
of the fan shroud
11.7 Alternator/coolant pump drivebelt
tensioner indicator position
Inset shows tensioner at maximum
adjustment11.3 Withdrawing the coolant
pump/alternator drivebelt tensioner
assembly. Note lug (A) on tensioner which
engages with hole (B) in mounting bracket

DOHC models
6Disconnect the battery negative lead.
7To provide additional clearance when
removing the cooling fan shroud assembly
(which is removed from below the vehicle),
apply the handbrake, then jack up the front of
the vehicle and support it securely on axle
stands (see “Jacking and Vehicle Support”).
8Disconnect the wiring plug(s) from the
motor(s), and where applicable, unclip the
wiring from the fan shroud.
9Unclip the expansion tank hose from the
fan shroud.
10Unscrew the two nuts securing the fan
shroud to the top of the radiator, then tilt the
top of the shroud away from the radiator, and
lift the shroud to release the lower securing
clips. Withdraw the assembly from below the
vehicle.
11To remove the fan blades, prise the
securing clip from the end of the motor shaft.12The motor can be separated from the fan
shroud by unscrewing the three securing nuts
and bolts.
13Where two cooling fans are fitted, both are
secured to the shroud in the same manner.
14Refitting is a reversal of removal, but
when fitting the fan blades, ensure that the
drive dog on the motor shaft engages with the
slot in the rear of the fan blades.
On CVH models, the cooling fan switch is
located on the right-hand side of the
thermostat housing (see illustration). On
DOHC models, the switch is located in the
end of the thermostat housing.
Removal and refitting of the switch is as
described for the temperature gauge sender.
Removal
1With the engine cold, slowly unscrew the
expansion tank cap to release any remaining
pressure from the cooling system. Remove
the cap.
2Place a suitable container beneath the
expansion tank.
3Disconnect and plug the upper hose.
4Where applicable, disconnect the coolant
level sensor wiring plug. 5Unscrew the expansion tank securing
screws, and tilt the tank so that the coolant
runs to the sealed end.
6Disconnect and plug the lower hose.
7Drain the expansion tank into the container
and remove the tank.
8Where applicable, the coolant level sensor
can be removed from the tank by unscrewing
the collar from the sensor, then withdrawing
the spacer, sensor and seal (see illustration).
Renew the seal if necessary. Note that the
sensor can only be fitted in one position (see
illustration). Refitting
9Refitting is a reversal of removal.
10On completion, top-up the coolant level to
the maximum mark, then refit the expansion
tank cap and run the engine at a fast idling
speed for several minutes. Check the
expansion tank for leaks, then stop the engine
and if necessary top-up the coolant level.
Removal
1On SOHC models, the temperature gauge
sender is located on the front left-hand side of
the cylinder head, just in front of the inlet
manifold. On CVH models, the sender is
located on the front face of the inlet manifold,
next to the thermostat housing. On DOHC
models, the sender is located at the front of
the inlet manifold (see illustration).
16Temperature gauge sender
- removal and refitting
15Expansion tank and coolant
level sensor - removal and
refitting
14Cooling fan switch -removal
andrefitting
3•8Cooling, heating and air conditioning systems
13.2 Fan blade securing clip and direction
of rotation arrow
15.8a Removing the coolant level sensor
from the expansion tank
16.3a Disconnect the temperature gauge
sender wiring - SOHC16.1 Temperature gauge sender location
(arrowed)16.3b Disconnect the temperature gauge
sender wiring - CVH
15.8b Fitting the coolant level sensor
14.1 Disconnecting the wiring plug from
the cooling fan switch

2With the engine cold, slowly unscrew the
expansion tank cap to release any remaining
pressure from the cooling system, then refit
the cap.
3Disconnect the wiring from the sender
terminal (see illustrations).
4Unscrew and remove the sender, and
temporarily plug the aperture.
Refitting
5Refitting is a reversal of removal, but smear
a little sealing compound on the sender unit
threads before fitting.
6On completion, check and if necessary top-
up the coolant level.
Removal
1Disconnect the battery negative lead.
2Remove the securing screws and unclip the
lower and upper steering column shrouds.
3Remove the four securing screws and
withdraw the instrument panel surround. Note
that the bottom right-hand screw is covered
by a plastic panel which must be prised out.
4Remove the passenger side lower facia
panel.
5Where necessary for improved access,
detach the two vent hoses from the left-hand
side of the heater, then detach the lower ends
of the two control cables from the heater by
removing the retaining screws (see
illustration).
6Unscrew the three securing screws, and
remove the heater control panel by sliding it
through the facia panel and withdrawing it
downwards. Disconnect the wiring from the
control panel illumination bulb.
7If necessary, the bulb can be removed with
its holder.
Refitting
8Refitting is a reversal of removal, bearing in
mind the following points.
9When reconnecting the wiring to the control
panel illumination bulb, wrap insulating tapearound the wiring loom over a length of
approximately 330.0 mm (13.0 in) starting
from the bulbholder. Route the loom, ensuring
that it is located in the two retaining clips,
bend it over and secure it to the bulbholder
with insulating tape as shown (see
illustration). This procedure will prevent the
wiring loom from chafing against the heater
control levers.
10When reconnecting the control cables to
the heater, move the control levers on the
control panel to the fully up position, then
attach the cables to the clips on the heater.
The cable ends should project from the clips
by between 0 and 4.0 mm (0 and 0.16 in). The
cables are adjusted automatically by moving
the control levers fully downwards. It is
possible that considerable resistance may
have to be overcome when moving the control
levers.
Removal
1Disconnect the battery negative lead.
2If the coolant is still hot, release the
pressure in the system by slowly unscrewing
the expansion tank cap. Place a thick rag over
the cap to prevent scalding as the pressure is
released.
3Note the location of the two heater hoseson the engine compartment bulkhead, then
disconnect and plug them (see illustration).
Alternatively, the hoses can be secured high
enough to prevent the coolant from draining.
4To prevent unnecessary spillage of coolant
when the heater unit is removed, blow into the
upper heater pipe until all the coolant has
been expelled through the lower pipe.
5Remove the two securing screws and
withdraw the heater pipe cover from the
bulkhead (see illustration). Recover the
gasket.
6Working inside the vehicle, remove the
passenger side lower facia panel.
7Disconnect the ends of the two control
cables from the heater by removing the two
retaining screws.
8Detach the five vent hoses from the heater.
9Unscrew the two mounting bolts, and move
the heater to the rear until the pipes are clear
of the bulkhead, then withdraw the heater to
the left. If necessary, remove the lower facia
bracket (see illustration).
Refitting
10Refitting is a reversal of removal, but
adjust the control cables by moving the levers
on the control panel to the top and then the
bottom stops. Considerable resistance may
be encountered when moving the levers
towards the bottom stops, which should be
overcome.
11On completion, top-up the coolant level.
18Heater unit - removal and
refitting
17Heater controls - removal and
refitting
Cooling, heating and air conditioning systems 3•9
3
18.3 Location of heater hoses on engine
compartment bulkhead18.9 Withdrawing the heater18.5 Heater pipe cover
17.9 Heater control panel illumination bulb
wiring loom correctly routed17.5 Heater control cable lower end fittings
(arrowed)