Nissan Maxima QX

since 1993 release

Repair and operation of the car

Nissan Maxima QX
+ Cars of the Nissan Maxima brand
+ Maintenance instruction
+ Settings and routine maintenance
+ Engine
- Cooling systems, heating
   General information
   Antifreeze - general information
   Check of serviceability of functioning and replacement of the thermostat
   Check of a condition of fans of the cooling system and chains of their inclusion, replacement of components
   Removal and installation of a radiator and expanded tank of the cooling system
   Check of a state and replacement of the water pump
   Check of serviceability of functioning and replacement of the block of the sensor of the measuring instrument of temperature of cooling liquid
   Check of serviceability of functioning of a driving electric motor of the fan of a heater and condition of components of its electric chain, …
   Removal and installation of an electric motor of the drive of the fan of a heater
   Removal and installation of assembly of the control panel of functioning of a heater and conditioner of air, adjustment of a driving cable
   Removal and installation of the heat exchanger of a heater
   Check of serviceability of functioning and service of systems of heating and air conditioning
   Removal and installation of a receiver dehumidifier To/in
   Removal, service and installation of the K/V compressor
   Removal and installation of the K/V condenser
+ Power supply system and release
+ Engine electric equipment
+ Control systems of the engine
+ Transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment

General information

Arrangement of components of cooling systems, heating and air conditioning in a motive compartment of the car

1 — the Radiator
2 — the Condenser
3 — the cooling system Fan
4 — the Water pump

5 — the Thermostat
6 — the Broad tank
7 — the Accumulator/dehumidifier

Thermostat components

1 — the Flange
2 — the Piston
3 — the pumping Valve
4 — the Main screw spring

5 — a valve Saddle
6 — the Main valve
7 — the Frame
8 — the Secondary screw spring

The scheme of circulation of cooling liquid with DOHC engines


The scheme of circulation of cooling liquid with SOHC engines


Schematic diagram of the air conditioning system


Function chart of the air conditioning system


Engine cooling system

All models of the cars considered in the present manual are equipped with the engine cooling system working with an excessive pressure with thermostatic management of circulation of working liquid. The water pump of rotor type is fixed on the block of the engine and provides pumping of cooling liquid through a cooling path of the last. The stream of liquid washes regions of an arrangement of each of cylinders in the block and goes to a back part of the engine. The cooling channels laid in casting of the block and a head of cylinders provide intensive cooling of inlet and final ports, areas of installation of spark plugs and the directing plugs of final valves.

The Voskozapolnenny thermostat controls the working temperature of the engine in the course of its warming up. The first minutes after start of the cold engine the thermostat remains closed, preventing thereby circulation of cooling liquid through a radiator. When temperature of the engine reaches normal working value, the valve of the thermostat opens, connecting the radiator providing the maximum intensity of the heat sink from a working body (cooling liquid) to a cooling contour.

The cooling system has a tight design and is densely closed by the cover of a radiator capable to maintain a certain excessive pressure that provides increase in a boiling point of cooling liquid and, respectively, efficiency of the heat sink through a radiator. At excess by internal pressure in system of some certain value, the sprung plate of the radiator of the safety valve which is built in in a cover rises over the saddle, providing an overflowing of excess of cooling liquid on a connecting (overflow) tube in a broad tank. In process of cooling of system liquid automatically comes back from a tank to a radiator.

Dolivaniye of cooling liquid in system is made through a mouth of a broad tank which at the same time acts also as the receiver accumulating in itself the excess of liquid which is forced out from a radiator.

In view of the listed features of a design, such cooling system received the name closed as in it any functional losses of cooling liquid are excluded.

System of heating

The main components of system of heating of salon are the electric fan and the heat exchanger located in a box-shaped casing of a heater. The heat exchanger by means of rubber hoses is connected to the engine cooling system. The control unit of functioning of the heater/conditioner of air is built in in the car dashboard. The cooling liquid warmed in the engine circulates via the heater heat exchanger, giving the to the air which is warmly filling a casing. At inclusion of heating of salon there is an opening of the lamellar gate therefore the internal volume of a casing of a heater connects to the volume of salon. At turning on of the fan the krylchatka of the last begins to banish the air given to salon via the heat exchanger, providing its intensive warming up.

Air conditioning system

Functional and basic schemes of the air conditioning system it is presented on accompanying illustrations.

The condenser installed ahead of a radiator, the evaporator, close to the heater heat exchanger, fixed on the engine block the compressor, and a receiver dehumidifier (accumulator) equipped with the reducing valve of high pressure are a part of system. All components are connected among themselves by refrigerator lines.

The fan banishes the air coming to salon through the evaporator heat exchanger working in the mode, the return to the mode of functioning of a radiator. The coolant which is pumped over via the heat exchanger begins to boil and, evaporating, selects excess of heat at air. Temperature in salon at the same time decreases to the required comfortable value (at the choice of the operator). The compressor supports circulation of coolant in system, pumping over the warmed liquid via the condenser where it is cooled and comes back to the evaporator.

 The cars considered in the present manual are equipped with system of additional safety of SRS better known as a safety cushion. Before performing any works near assembly of a pillow or a steering column, without fail disconnect system in order to avoid getting injured as a result of its casual operation, - disconnect from the battery at first a negative, then positive wire and wait not less than two minutes before starting service of the components located near sensors of the directed overloads (see the Head for Onboard electric equipment). Isolation and contact sockets of an electrical wiring of a chain of SRS are painted in bright yellow color. It is not necessary to connect any diagnostic units to this chain!