1994 JEEP CHEROKEE cooling

The reinforcement bracket is held on the
frame rail with two blind rivets.
(2) Remove the bracket and tow hook from frame
rail.
INSTALLATION
(1) Position bracket and tow hook on the frame
rail.
(2) Install bolts that attach tow hook bracket to
frame rail and reinforcement bracket. Tighten bolts
to 75 Nzm (55 ft-lbs) torque.
TRAILER HITCHES
CLASS III HITCHÐXJ VEHICLES
A class III weight-distributing/equalizer type hitch
can be used to tow a trailer:
²having a maximum gross weight of 5,000 lbs/2250
kg, and
²having a maximum tongue weight of 750 lbs/332
kg).
The following vehicle basic equipment is required
for class III trailer towing:
²P205/75R15 or larger tires;
²full size spare tire;
²trailer sway control;
²trailer tow wire harness and connector;
²heavy duty turn signal flasher element;
²heavy duty axle (with synthetic lubricant);²heavy duty cooling system;
²heavy duty generator/battery;
²auxiliary automatic transmission fluid cooler; and
²I-6, 4.0L engine.
Wide-angle type door mirrors are recommended but
not required.
WIRE HARNESS CONNECTORS
CLASS I HITCH CONNECTOR
The trailer tow wire harness connector for class I
trailer hitches is a 5-terminal, in-line type connector.
Terminal 5 is the source for vehicle ground.
CLASS III HITCH CONNECTOR
The trailer tow wire harness connector for class III
trailer-tow hitches is a 7-terminal, circular type con-
nector.
The 12-volt circuit for the trailer is protected
from overloads. A auto-reset type circuit
breaker is located in the trailer tow wire har-
ness near the plug-in relays.
CAUTION: The trailer tow wire harness package
does not include a vehicle battery isolator unit. Be-
cause of this, the trailer battery can totally dis-
charge the vehicle battery if the engine is not
operated for an extended period of time.
Fig. 11 Trailer Tow Wire Harness Connectors
23 - 88 BODY COMPONENTSÐXJ VEHICLESJ

SERVICE DIAGNOSISÐMECHANICAL
GENERAL
The reason for a decrease in cooling or heating ef-
ficiency must be understood before attempting repair
or replacement of parts. Determined if the condition
is the air conditioner, the heating system, its compo-
nents or the in the air flow system.
The air conditioning system generally operates at
peak efficiency at normal highway speeds. However,
a slight reduction in A/C performance may be expe-
rienced in congested city driving conditions; espe-
cially when ambient temperatures are high.
When diagnosing a gradual decrease in A/C perfor-
mance, remember to check condition of the condenser
and radiator fins. Air flow blockage of either compo-
nent, caused by dirt, foreign material or insects, will
affect the air conditioning and engine cooling sys-
tems. Vehicles equipped with a protective screen, can
restrict air flow to the radiator and condenser.
During high outside operating temperatures, a
slight increase in engine coolant temperature will oc-
cur when the air conditioner is operating.
A/C PERFORMANCE TEST
The pressure developed on the high side and low
side of the compressor indicates whether the system
is operating properly.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A DI-
RECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
WARNING: WEAR SAFETY GOGGLES WHEN SER-
VICING THE REFRIGERATION SYSTEM
(1) Attach an engine tachometer and refrigerant
Pressure Gauge and Manifold Assembly Tool
C-4740-A.
(2) Close both hand valves on the gauge and man-
ifold assembly.
(3) Set both service hand valve stems to the mid-
position.
(4) Engine should be warmed up with doors, win-
dows and hood closed.
(5) Operate air conditioning system with the en-
gine running at 1,000 RPM. Set the controls for max-
imum A/C, temperature control on full cool and
blower switch on high.
(6) Insert a thermometer into center discharge air
outlet and observe the air temperature. The temper-
ature should be approximately 7ÉC (45ÉF) at 27ÉC
(80ÉF) ambient temperature after 5 minutes of oper-
ation.(7) Observe the high and low side pressures. The
evaporator suction pressure should be 207-241 kPag
(30-35 psig). The compressor discharge pressure
should be 1103-1633 kPag (160-235 psig). It should
be noted that high ambient temperature and humid-
ity conditions will cause higher pressures and tem-
perature conditions. If the clutch cycles, take
readings before clutch disengages.
(8) If pressures are abnormal, refer to the Pressure
and Performance Diagnosis Charts.
The following charts have been developed for quick
reference. If the step by step method used is not com-
pletely understood, refer to the correct section of the
Service Manual for more detailed information.
COMPRESSOR VALVE PLATEÐLEAK TESTS
This test can be preformed with the compressor in-
stalled in the vehicle.
Discharge or Suction Valve BreakageÐWhen
compressor is operating at idle speed, compressor
makes a ``clacking'' sound. Preform the Pressure Bal-
ancing Test.
Head Gasket BreakageÐAt idle speed, discharge
pressure does not increase to normal condition and
suction pressure is high. Preform the Pressure Bal-
ancing Test.
Pressure Balancing Test:
(1) Connect manifold gauge set to suction and dis-
charge ports.
(2) Run compressor for 5 minutes at idle speed and
stop.
(3) Measure elapsed time that discharge pressure
is balanced to suction pressure. If less than 2 min-
utes, it is determined that discharge valve or head
gasket is broken.
REFRIGERANT LEAK TEST
External leaks in the system can be located using
an electronic detector.
The electronic leak detector is recommended be-
cause it is light, accurate and most important, does
not expose the user to toxic gas fumes. An electronic
leak detector will locate R-12 leaks as small as 15 ml
(0.5 fluid oz.) per year.
WARNING: DO NOT USE A HALIDE TORCH. THE
HALIDE TORCH REQUIRES AN OPEN FLAME FOR
LEAK DETECTION. WHEN R-12 IS EXPOSED TO AN
OPEN FLAME, IT TURNS INTO PHOSGENE GAS
WHICH IS POISONOUS.
(1) Calibrate the detector as outlined in the manu-
facturer's instructions.
(2) Remove the flexible detector probe from the
case.
(3) Turn the detector control switch ON.
24 - 8 HEATING AND AIR CONDITIONINGJ

SERVICE DIAGNOSISÐELECTRICAL
BLOWER CONTROLSÐXJ VEHICLES
DESCRIPTION
The blower motor delivers air to the inside of the
vehicle. Its speed is controlled by the blower switch
and the blower resistors. With the switch in LO, part
of the battery voltage is supplied to the motor
through all of the resistors. The motor runs slowly.
As the blower switch is moved to a higher speed, the
switch allows more voltage to be applied to the
blower motor, which will increase its speed. When
the switch is in HI, the blower resistors are bypassed
and battery voltage is applied directly to the blower
motor. The motor runs at the fastest speed in this
mode.
DIAGNOSIS
Refer to the Group 8W, Wiring Diagrams for com-
plete system schematic.
1. BLOWER MOTOR INOPERATIVE
²Remove and inspect fuse. If the fuse is blown, re-
place fuse.
2. BLOWER MOTOR INOPERATIVE (HI Posi-
tion)
Put the ignition switch in RUN, the select switch
in HEAT and the blower switch on HI.
²Blower motor connector (Terminal A) should be
battery voltage. If not go to next step.
²Blower motor connector (Terminal B) should be 0
ohms. If not, repair wire to ground.
²Blower switch connector (Terminal C) should be
battery voltage. If battery voltage replace blower
switch. If not, replace select switch.
3. BLOWER MOTOR INOPERATIVE (LO, M1
& M2 Positions)
Ignition switch in RUN, select switch in HEAT.
²Blower resistors connector (Terminal D) should be
battery voltage. If not, replace select switch.
²Blower resistors connector (Terminal C) should be
battery voltage. If not, replace blower switch.
²Blower resistors connector (Terminal A) should be
battery voltage. If not, replace blower switch.
²Blower resistors connector (Terminal B) should be
battery voltage. If not, replace blower resistor.
AIR CONDITIONING SYSTEMÐXJ VEHICLES
DESCRIPTION
The A/C Compressor Clutch is belt-driven by the
engine. A clutch, operated by a solenoid, automati-
cally turns the compressor on and off to control evap-
orator icing.
The A/C Compressor Clutch operation is controlled
by several components: the A/C Low-Pressure
Switch, Thermostat Switch, Fuel Pump Relay, A/C
Clutch Relay and the Engine Controller.The A/C low pressure switch opens when there is
not enough refrigerant in the system. When this hap-
pens, voltage is no longer present at the Engine Con-
troller. The Engine Controller will turn off the A/C
clutch relay. With the proper refrigerant level in the
system, the low pressure switch remains closed.
When the evaporator temperature is low enough to
ice the cooling coils, the thermostat switch opens.
The Engine Controller will turn off the A/C clutch.
The thermostat switch closes when the temperature
rises. The Engine Controller will then turn the A/C
clutch relay on again.
DIAGNOSIS
Refer to the Group 8W, Wiring Diagrams for com-
plete system schematic.
With engine running, Engine Controller may delay
A/C clutch up to 30 seconds.
1. A/C COMPRESSOR CLUTCH INOPERA-
TIVE
Clutch connector disconnected.
²Jumper fused test lead, battery to clutch connec-
tor, clutch should operate. If not, replace compressor
clutch assembly.
2. A/C LOW PRESSURE SWITCH
Ignition in RUN, A/C controls in MAX or NORM.
²Low pressure switch connector (Terminal A)
should be battery voltage. If not, repair open to select
switch.
²Low pressure switch connector (Terminal C)
should be battery voltage. If not, check switch resis-
tance and check freon pressure.
3. A/C CLUTCH RELAY
Engine RUNNING, A/C controls in MAX or
NORM.
²Relay connector Pin 4 to ground should be battery
voltage. If not, check fuse F6 in Power Distribution
Center.
²Ground A/C clutch relay (Terminal 5) should have
A/C compressor clutch engagement. If not, check En-
gine Controller Terminals 27, 28 and 34.
HEATING SYSTEMÐYJ VEHICLES
DESCRIPTION
The blower motor circuit begins at a 25 amp fuse
that receives its battery feed from the ignition
switch. From the fuse the circuit extends to a micro-
switch mounted on the heater control.
The micro-switch is normally closed is operated by
a cam on the heater control lever. In all heater con-
trol lever positions, except OFF and VENT, the
blower motor electrical circuit is complete. In the
OFF and VENT positions the cam depresses the mi-
cro-switch lever opening the electrical circuit to the
blower motor.
24 - 14 HEATING AND AIR CONDITIONINGJ

COMPRESSOR OVERHAUL
INDEX
page page
Compressor............................. 17
Compressor Isolation...................... 17
Description............................. 17Magnetic Clutch......................... 18
Purging Compressor of Air................. 17
DESCRIPTION
The A/C system uses a Sanden compressor. This
compressor is a 7 piston design. Designated the SD-
709, the compressor is mounted on the front right
side of the engine and is driven by a serpentine belt.
System lubrication is provided by 135cc615cc (4.6
cu. in.60.5 cu. in.) of 500 viscosity refrigerant oil.
The clutch used on the compressor consists of 3 ba-
sic components: the pulley, front plate and the field
coil. The pulley and field coil are attached to the
front head of the compressor with tapered snap rings.
The hub is keyed to the compressor shaft and is re-
tained on the shaft with a self-locking nut. Special
service tools are required to remove and install the
clutch plate on the compressor shaft.
COMPRESSOR ISOLATION
It is not necessary to discharge the system for com-
pressor removal. The compressor can be isolated from
the remainder of the system and eliminate the need
for recharging when performing compressor service.
(1) Connect pressure gauge and manifold.
(2) Close both gauge hand valves.
(3) Mid-position both service valves.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A DI-
RECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(4) Start the engine and operate the air condition-
ing system.
(5) Turn the suction service valve slowly clockwise
toward the front seated position.
(6) When pressure drops to zero, stop the engine
and compressor and quickly finish front-seating the
suction service valve.
(7) Front-seat the discharge service valve.
(8) Loosen the oil level check plug slowly to re-
lease any internal pressure in the compressor.
The compressor is now isolated from the remainder
of the system.
The service valves can be removed from the com-
pressor.
PURGING COMPRESSOR OF AIR
The compressor must be purged of air whenever it
has been isolated for an oil level check or other ser-
vice procedures without discharging the entire sys-
tem.
(1) Cap the service gauge ports on both of the ser-
vice valves.
(2) Back-seat the suction service valve to allow the
system refrigerant to enter the compressor.
(3) Place the discharge service valve in the mid-po-
sition or cracked-position.
(4) Loosen the discharge service valve gauge port
cap to permit the refrigerant to force any air out of
the compressor.
(5) Back-seat the discharge service valve and
tighten the gauge port cap.
(6) The compressor is now ready for service.
COMPRESSOR
REMOVAL
(1) Isolate the compressor.
(2) Disconnect negative cable from battery.
(3) Disconnect the clutch lead wire.
(4) Remove the discharge and inlet (suction) ser-
vice valves from the compressor. Plug or tape all the
openings.
(5) Remove the serpentine drive belt (refer to
Group 7, Cooling System for the proper procedure).
(6) Remove the bolts and lift the compressor from
the mounting bracket (Figs. 1 and 2).
INSTALLATION
If a replacement compressor is being installed;
check the oil level. Add or subtract oil as neces-
sary and install the magnetic clutch on the com-
pressor.
(1) If the mounting bracket was removed, install
the bracket to the block. Tighten the mounting bolts
to 27 NIm (20 ft. lbs.) torque.
(2) Install the compressor on the mounting
bracket. Tighten the bolts to 27 NIm (20 ft. lbs.)
torque.
(3) Install the serpentine drive belt (refer to Group
7, Cooling System for the proper procedure).
(4) Tighten the serpentine drive belt to the speci-
fied tension.
²New belt tensionÐ800-900 N (180-200 lb-f).
JHEATING AND AIR CONDITIONING 24 - 17

CLIMATE CONTROL SYSTEMÐXJ VEHICLES
INDEX
page page
A/C Recirculating Air Door Vacuum Motor
Replacement.......................... 31
Blower Motor Resistors Replacement......... 35
Blower Motor/Fan Replacement.............. 26
CondenserÐ4.0L Engines.................. 32
Condenser/Receiver DrierÐ2.5L Engines....... 31
Defroster Duct Replacement................ 29
Description............................. 22
Evaporator Coil.......................... 34
Evaporator/Blower Housing................. 33Expansion (H) Valve...................... 35
Heater and A/C Control Panel Replacement.... 26
Heater Control Cable Replacement........... 30
Heater Core............................ 28
Heater Core Housing Replacement........... 29
Heater/Defroster/Instrument Panel Outlet Door
Vacuum Motor Replacement............... 30
Receiver DrierÐ4.0L Engines............... 32
Temperature Control Thermostat............. 35
DESCRIPTION
The Climate Control System combines air condi-
tioning, heating and ventilating capabilities for vehi-
cles equipped with air conditioning. Vehicles without
air conditioning perform heating and ventilating
functions without the air conditioning evaporator.
Both systems consist basically of 2 parts:
²Blower and Air Inlet Assembly
²Heater Core and Air Distribution Assembly
These assemblies, initially installed as a single
unit, may be removed separately from under the in-
strument panel as required for service.
HEATER SYSTEM
The heater system is a blend air type. Outside air
is heated and then blended in varying amounts with
cooler outside air to obtain the desired discharge
temperature. A heater coolant valve provides full
flow to the heater core for all heating modes. The
heater coolant valve remains closed for the ventila-
tion mode, allowing discharge air to approach the
outside ambient air temperature.
AIR CONDITIONING SYSTEM
The air conditioning system has an evaporator to
cool and dehumidify the incoming outside air prior to
blending with the heated air. The evaporator is in
operation during the A/C mode and also in the de-
frost mode for defogging purposes. The evaporator is
not in operation at ambient temperatures below ap-
proximately -1ÉC (30ÉF). To maintain minimum evap-
orator temperature, a fixed thermostat setting switch
cycles the compressor clutch. The blower is operatingthe heater or air conditioning systems, except the
OFF mode. In this mode (OFF) the blower and the
outside air are shut off.
The cooling unit is mounted on the dash panel and
the cooled air is discharged from the instrument
panel registers. The registers are adjusted to provide
general or localized cooling.
SIGHT GLASS
The sight glass is located on top of the receiver/
drier. The sight glass provides a visual check of the
system refrigerant level. A continuous stream of bub-
bles will appear in the sight glass when the system
charge is low. Bubbles will not appear when the sys-
tem is fully charged.
LOW PRESSURE SWITCH
The low pressure switch disengages the magnetic
clutch if the pressure in the system drops below 193
kPa (28 psi). This will occur with a loss in refriger-
ant or with cold ambient temperature.
HEATER VALVE
The heater valve regulates coolant flow to the
heater core. It requires vacuum to shut off flow to
the heater core.
These vehicles are equipped with a bypass-type
heater water valve. When the heater valve is closed,
coolant flow to the heater core is bypassed back to
the engine. When the heater valve is open, coolant is
directed through the heater core and back to the en-
gine.
24 - 22 HEATING AND AIR CONDITIONINGJ

(4) Connect the heater hoses to the heater core.
(5) Fill the cooling system.
HEATER CORE HOUSING REPLACEMENT
(1) Remove the evaporator/blower housing.
(2) Remove the heater core.
(3) Remove the defroster duct.
(4) Disconnect the vacuum hoses from the heater
core housing vacuum motors.
(5) Remove the heater housing retaining nuts in
the engine compartment. Remove the heater core
housing.
(6) Transfer the vacuum motors, etc. to the re-
placement housing.
To install the heater core housing, reverse the re-
moval procedure.
DEFROSTER DUCT REPLACEMENT
REMOVAL
(1) Disconnect negative cable from battery.
(2) If equipped with center console remove the con-
sole as follows:
(a) MANUAL TRANSMISSIONÐRemove shift
knob, boot and bezel.
(b) AUTOMATIC TRANSMISSIONÐRemove
shift handle by pulling up. Remove the shift bezel.
(c) POWER MIRRORSÐPry mirror switch out of
console cover (Fig. 13). Disconnect switch connector
(Fig. 14).
(d) Remove console cover screws (Fig. 14).
(e) Remove console cover from base (Fig. 15).
(f) Remove console base (Fig. 15).
(3) Remove the lower instrument panel.
(4) Remove the left kick panel.
(5) Remove the instrument panel retaining bolt.
(6) Remove the instrument panel retaining bolts
located at the steering column.
(7) Remove the right and left A-pillar trim.(8) Remove the defroster bezel attaching screws
and bezel (Fig. 16).
Fig. 13 Power Mirror Switch
Fig. 14 Console Cover Screws and Power Mirror
Switch Connector
Fig. 15 Console Cover and Base
JHEATING AND AIR CONDITIONING 24 - 29

INSTALLATION
(1) Remove the plugs from the receiver/drier open-
ings. Install receiver/drier into the condenser.
(2) Install the condenser to the radiator. Tighten
the retaining bolts.
(3) Install the radiator and condenser as an assem-
bly (refer to Group 7, Cooling System for the proper
procedure).
(4) Plug the harness into the low pressure switch
(Fig. 21).
(5) Connect the A/C hoses to the condenser.
(6) Connect the transmission cooler lines (if
equipped with automatic transmission).
(7) Connect the fan shroud and the radiator hoses.
(8) Add 30 ml (1 fluid oz.) of refrigerant oil to the
system if the condenser was replaced.
(9) Fill the cooling system.
(10) Charge the A/C system.
CONDENSERÐ4.0L ENGINES
REMOVAL
(1) Disconnect the fan shroud and electric fan from
the radiator.
(2) Remove the upper crossmember and bracket.
(3) Evacuate the A/C system, disconnect the A/C
hoses from the condenser and plug the openings.
(4) Remove the attaching hardware and brackets
securing the condenser to the radiator.
(5) Remove the condenser.
INSPECTION
When servicing a condenser for a leak at the bot-
tom, inspect the lower crossmember for an ID tag.
This tag may rub against the condenser. If the con-dition exists, remove the tag prior to installing a new
condenser.
INSTALLATION
(1) Install the condenser.
(2) Remove the plugs from the openings. Connect
the A/C hoses to the condenser.
(3) Install the upper crossmember and bracket.
(4) Connect the fan shroud and electric fan to the
radiator.
(5) Add 30 ml (1 fluid oz.) of refrigerant oil to the
A/C system if the condenser was replaced.
(6) Charge the A/C system.
RECEIVER DRIERÐ4.0L ENGINES
REMOVAL
(1) Evacuate the A/C system, disconnect the A/C
hoses from the receiver dryer and plug the openings
(Fig. 22).
(2) Unplug the harness from the low pressure
switch.
(3) Remove the nut attaching the receiver dryer to
the side sill weld stud.
(4) Remove the receiver dryer.
INSTALLATION
(1) Install the receiver dryer.
(2) Install and tighten the nut attaching the re-
ceiver dryer to the side sill weld stud.
(3) Plug the harness to the low pressure switch.
(4) Remove the plugs the openings. Connect the
A/C hoses to the receiver dryer.
(5) Charge the A/C system.
Fig. 21 Condenser Receiver DrierÐ2.5L Engine
Fig. 22 Receiver DryerÐ4.0L Engine
24 - 32 HEATING AND AIR CONDITIONINGJ

CLIMATE CONTROL SYSTEMÐYJ VEHICLES
INDEX
page page
A/C Blower Motor........................ 43
A/C Condenser.......................... 42
A/C Control Panel........................ 41
Blower Motor (Heating).................... 40
Blower Motor/Air Door Motor Switch Replacement . 39
Defroster Nozzle and Duct................. 40
Description (Air Conditioning)................ 41
Description (Heating)...................... 37
Evaporator and Housing................... 42
Expansion (H) Valve...................... 43Fresh Air Door Vacuum Motor............... 41
Fresh Air Intake Duct..................... 41
Fresh Air Ventilation...................... 39
Heater Control Panel Replacement........... 39
Heater Core and Housing.................. 40
Heater/Defroster Operation................. 37
Receiver-Drier Replacement................ 42
Sight Glass............................. 41
Vent Door Control Cables.................. 39
DESCRIPTION (HEATING)
A blend-air heating system is used in YJ vehicles.
The blend-air system provides a constant flow of en-
gine coolant through the heater core.
The temperature of heated air entering the passen-
ger compartment is controlled by regulating the
quantity of air flow through the heater core. This is
accomplished by blending a controlled amount of un-
heated air from outside the vehicle with heated air
from the heater core.
HEATER/DEFROSTER OPERATION
The heater core is connected to the engine cooling
system. It operates on the circulation of heated en-
gine coolant through the core and a supply of fresh
air drawn in through the intake grille on the cowl.
Engine coolant flows through the heater core at all
times.
The heater controls are on the heater control panel
(Fig. 1).
The air control lever (Fig. 1) operates a door in the
fresh air intake duct. The door controls the amount
of fresh air flow into the heater housing and core.
When the lever is in the OFF position, the intake
door is closed preventing air flow into the housing.The temperature control lever (Fig. 1) determines
air flow through the heater core. The lever operates
the heater housing blend-air door which controls air
flow through the core.
The blower motor is operated by the control switch
(Fig. 1). The switch provides 3 blower speeds for in-
creased air flow in heat or defrost mode.
HEATING
Maximum air flow and heater output occurs when
the air control lever is in HEAT position and the
temperature control lever is in WARM position. The
blend-air door is closed and all intake air is directed
through the heater core in this operating mode (Fig.
2).
Temperature regulation of the heated air is deter-
mined by position of the temperature control lever.
Moving the control lever from WARM to an in-be-
tween position, opens the blend-air door in the heater
housing. As the door opens, unheated outside air is
drawn into the system and blended with heated air
from the core.
DEFROSTING
The heater housing contains a defroster door to di-
vert heated air to the defroster duct and windshield
outlets (Fig. 2). Defrost air flow is controlled by the
air control lever.
For defroster operation, the air control lever must
be moved to the defrost detent. The detent is identi-
fied by the defrost symbol on the control panel. In
this position, the defroster door in the heater housing
diverts all heated air (from the core) to the defroster
duct windshield outlets.
If the air control lever is moved to any position be-
tween the heat and defrost detents, the defroster door
does not close completely. In this mode, the door re-
mains partially open causing heated air to be divided
equally between the heat and defrost outlets.
Fig. 1 Heater Control Panel
JHEATING AND AIR CONDITIONING 24 - 37