Ventilation system of the VAZ-2121 car - supply and exhaust
When the car is moving, air is forced into the cabin by natural pressure through the air intake slots on the hood and is sucked out through the holes in the rear roof pillars
To increase air circulation when driving, you can lower the front door windows, and at low speeds, turn on the electric fan.
Heating and ventilation system: 1 – side nozzle; 2 – side nozzle air duct; 3 – air duct for heating the windshield; 4 – central nozzles; 5 – control rod for air supply damper; 6 – air supply damper; 7 – radiator; 8 – heater seal; 9 – radiator casing; 10 – outlet pipe; 11 – supply pipe; 12 – tap; 13 – air distribution cover; 14 – fan casing; 15 – impeller; 16 – electric motor; 17 – crane control rod; 18 – control rod for the heated windshield damper; 19 – bracket for heater control levers; 20 – air supply damper control handle; 21 – control handle for the heated windshield damper; 22 – crane control handle
Air flows in the cabin are distributed by air ducts located inside the dashboard.
Air flows to the windshield through the upper slot-like nozzles on the instrument panel, to the side windows - through the side and, partially, central nozzles (with air flow guides), to the feet - through the holes in the heater casing (with the cover folded down).
Heater operation diagram: 1 – air distribution cover; 2 – fan casing; 3 – fan electric motor; 4 – impeller; 5 – radiator; 6 – supply pipe; 7 – outlet pipe; 8 – radiator casing; 9 – air supply damper; 10 – air supply box; 11 – air duct for heating the windshield; 12 – central nozzle flap; 13 – central nozzle; 14 – crane control handle; 15 – control handle for the heated windshield damper; 16 – air supply damper control handle; 17 – control lever bracket; 18 – windshield heating flap; 19 – control rod for the heated windshield damper
To control the distribution of air flows, the middle and lower levers on the center console of the instrument panel, as well as the guides of the central nozzles and their regulators, are used.
The heating system is liquid, combined with the engine cooling system.
The heater radiator is installed in the instrument panel console in a plastic casing and sealed around the perimeter with foam tape.
Air heating depends on the degree of opening of the valve that regulates the flow of liquid through the radiator.
The valve is installed at the inlet of the radiator and is controlled by the upper lever on the center console.
Electric motor of the ME-255 fan – commutator, DC, with excitation from permanent magnets.
The fan speed is controlled by a three-position switch on the instrument panel.
Depending on the selected speed, the electric motor is connected to the vehicle’s on-board network directly (high frequency) or through an additional resistor (low frequency).
Rotation speed of the electric motor shaft with an impeller at a voltage of 12 V and an air temperature of 25±10°C – 3000±150 min –1 .
Current consumption at maximum rotation speed is no more than 4.5 A.
The fan impeller is mounted on the motor shaft.
The electric motor cannot be repaired; if it fails, it must be replaced.
Heating and ventilation system malfunctions
- Cause of malfunction
Elimination method
Heater fan motor does not work:
- The heater switch is faulty (check with an ohmmeter)
Replace the switch
- The wires are damaged, their tips are oxidized or loose, fuse No. 1 is blown (no voltage is supplied to the electric motor)
Crimp the terminals, strip the tips, replace faulty wires, a blown fuse (checking the circuits it protects for short circuits)
- Wear, freezing of electric motor brushes, break in the armature winding, oxidation, wear of the commutator (voltage is supplied to the electric motor, but it does not rotate)
Replace the electric motor
- Short to ground of the armature winding (when turned on, the fuse immediately blows)
Replace the electric motor
Heater fan motor does not work at low speed:
- Burnt will add spruce resistor, its wires are damaged or their tips are loose
Replace the resistor, crimp the terminals, strip the tips, replace faulty wires
- Heater switch is faulty
Replace the switch
Heater fan motor armature rotates slowly:
- The collector is dirty or oxidized, the armature winding has an interturn short circuit (the fuse may blow). Seizing of the armature shaft in the bearings (creaking, squealing, the fuse may blow)
Replace the electric motor
The car interior does not heat up well:
- Insufficient coolant temperature
Thermostat valve is stuck in the open position. Replace the thermostat
- Not enough liquid in the cooling system
Add cooling system fluid, check the connections for tightness.
- Crane jamming in the closed position, cable flaps jamming or control cables breaking, loosening their fastening
Replace faulty faucet, cables, valves. Securely fasten the cable sheaths, lubricate the cables with engine oil, adjust the drives
- Heater radiator is faulty
Replace the radiator
The temperature in the cabin is not adjustable:
- Jamming of the heater valve, dampers, cables in sheaths or their breakage, loose fastening of the cable sheaths
Replace faulty faucet, cables, valves. Securely fasten the cable sheaths, lubricate the cables with engine oil, adjust the drives