Operation and Components
Control Panel Labels:
A. General information
Model 201 has a blend air heating system in combination with air conditioning - Tempmatic climate control. The cooling and heating air temperatures are automatically controlled.
For adaptation to weather conditions, a number of functions, including air distribution, can be push-button-controlled (b), independent of in-car temperature. Open, close or adjust dashboard center and side outlets as required.
5 Control unit consists of:
a Temperature selector wheel
b Push-button switch with 6 functions
c Air conditioning switch (mode buttons)
15 Blower switch
26 Fresh/recirculated air switch
The blower can be manually adjusted except for modes "Defrost" or "Vents Closed"
A change from fresh air to recirculated air intake can he made at any time by means of switch (26).
The "cooling" mode requires the pressing of button (c) into position "Maximum Cooling" or "Normal" and to push one of the buttons of push-button switch (b).
The system operates only with the engine running.
B. Function of temperature control
The in-car temperature is controlled by blend air flaps. If "heating" is required, the heater valve is fully opened by a vacuum element (41) and remains fully open during the heating period.
The blend air flaps (arrow) mix unheated air with the heated air, routed through the heat exchanger. The position of the blend air flaps is indicated by a feedback potentiometer for flap position (4) flanged to the shaft of the blend air flaps, and transmitted to the electronic system in the control unit.
The blend air flaps are operated via levers by a vacuum element (37). The vacuum element is connected to 2 switchover valves.
The switchover valve (11.4) supplies the vacuum element with vacuum through an orifice, so that the blend air flaps are moving toward "cold". The second switchover valve (11.3) connects the vacuum element to atmosphere also through an orifice, so that the blend air flaps are moved in the direction of "warm" by the spring in the vacuum element. From max. cooling or not heating up to max. heating and vice versa the blend air flaps require approx. 20 seconds each.
Example:
If there is a temperature difference between in-car sensor and preset value on temperature wheel (e.g. too cold by 0.3 °C) the electronic system will energize the switchover valve "warm". Valve (11.3) opens and slowly connects the vacuum element (37) to atmosphere by an orifice. The spring in vacuum element moves the blend air flaps in direction of "warm" until the feedback potentiometer for flap position (4) indicates the resistance value which corresponds with the temperature difference. The switchover valve (11.3) "warm" will then close and the blend air flaps will stop. Vice versa, the switchover valve (11.4) "cold" is opened. The vacuum element is supplied with vacuum until the proper position of the blend air flaps has been attained. The switchover valve (11.4) "cold" will then close. If no heating is required, the heater valve is closed and the blend air flaps are resting against the "cold" stop. In such a case, the temperature in evaporator is probed and the air conditioning system is switched on, if required.
C. Push-button switch unit with electronic temperature control
a Temperature wheel
b Push-button switch Unit with 6 functions (buttons)
C Mode switch for air conditioning system with 3 functions (buttons)
Try push-button switch unit consists of a temperature wheel (a) a push-button switch (b) with 6 push-buttons and a mode switch for air conditioning (c). The push-button switch unit houses the electronic system for controlling interior temperature and 1 relay each for connecting the current for the electromagnetic clutch of the refrigerant compressor (air conditioning compressor) and auxiliary coolant pump.
g Fuse, 2 amps
A fuse (g) is located at the rear of the push-button switch unit as protection for the electronic system and conductors against short-circuits.
Temperature wheel (a)
The temperature wheel (a) provides stepless interior temperature control in a temperature range from approx. 16 °C to 32 °C. If the temperature wheel is set at the end position "MIN", the system operates at full cooling capacity, provided the air conditioning system has been switched on. If it is set at the end position "MAX", the system operates at full heating capacity.
Rotation of the temperature wheel changes the resistance (potentiometer), transmitting the new resistance value into the electronic system of the temperature control.
Push-button switch (b) with function selection
Function (push-button) selection "Defrost"
The blower runs at max. speed in 4th stage at 100 % fresh air supply, provided the switch fresh air/recirculating air is set to fresh air.
The blower switch and tie temperature wheel are bypassed (inoperative) and the recirculating pump runs continuously. The windshield is provided with max. heated air depending on motor temperature The air feed to center and side outlets can be set manually using the levers The center outlets should be closed.
The functions of the air conditioning mode switch are bypassed (canceled) and the air conditioning system operates at max. capacity similar to adjustment "Maximum Cooling", provided the outside temperature is above 0 °C. To guarantee perfect function of "defrost", the fresh air/recirculating air switch should always be set to fresh air.
Function (push-button) selection "Defogging"
The blower runs in the stage to which the blower switch has been set, but at least in 1st stage. The blower stages can be changed by the blower switch. The heating or cooling capacity is controlled in accordance with nominal value adjustment on the temperature wheel in combination with the mode switch of the air conditioning system (c). If the air conditioning has been switched on, with the switch for fresh air/recirculating air (26) set to fresh air and the temperature difference (preset temperature on temperature wheel in relation to outside temperature) is greater than 8 °C, the system will automatically switch to recirculating air.
The recirculating air mode is also influenced by the interior temperature From interior temperatures of 25 °C to 50 °C the temperature difference is constantly reduced toward 0 °C. If the temperature difference (outside temperature drops) reduces to approx. 5 °C, the system is again switching to fresh air.
With the heater valve opened, the recirculating pump runs continuously in heating mode.
All the air flow is directed to the windshield. Air flow to center and side outlets can be adjusted manually using the respective levers.
Push-button selection "Bi-Level"
Similar to push-button selection "Defogging" except for air distribution, defroster nozzle flaps and legroom flaps opened.
Push-button selection "Heating"
Similar to push-button selection "Defogging" except for air distribution, leak air from defroster nozzles, legroom flaps fully opened.
Push-button selection "Normal A/C or Vent"
Similar to push-button selection "Defogging" except for air distribution. Air out of center and side outlets only. Center and side outlets must be opened manually.
Push-button selection "Vents Closed"
Blower is switched off and the fresh air/recirculating air flap is closed.
Recirculating pump is not running. Temperature control continues operating and the heater valve is opened or closed as required. Air conditioning is switched off.
NOTE: If none of the selection push-buttons is depressed, this function conforms to selection "Heating"
Air conditioning mode switch (c) with push-button selection
Functioning of the air conditioning mode switch requires engagement of one of the selections on the push-button switch unit:
Push-button selection "Maximum Cooling"
This selection dehumidifies the fresh air, while also dehumidifying the vehicle's interior air.
The refrigerant compressor is constantly switched on and the evaporator temperature is constantly regulated to 0 °C - +2 °C.
If necessary, the temperature set on the temperature wheel is achieved by additional heating.
Push-button selection "Normal A/C"
With this mode selection the refrigerant compressor is also engaged as necessary. During the heating operation and as long as no cooling is required, The system operates (refrigerant compressor off) similar to mode selection "Economy". But if the temperature in the vehicle increases by approx. 0.8 °C above nominal value (wheel value), the compressor begins to operate. The air conditioning output is then regulated according to deviation between nominal/actual value.
An additional requirement for engagement of the refrigerant compressor is that the blend air flaps and the heater valve are closed. The outside temperature should also be >0 °C.
Push-button selection "Economy"
In this position, the refrigerant compressor is switched off and the system operates with 100 % fresh air. If the temperature in the vehicle rises above the value set on the temperature wheel, Unheated outside air will be routed into the vehicle.
NOTE: If none of the air conditioning mode buttons is depressed, it will correspond with selection "Normal A/C"
D. Temperature sensor and feedback potentiometer for flap position
In-car temperature sensor
The in-car temperature sensor (1) is located in roof frame lining, in range of interior lamp.
The resistance of current flow through the in-car temperature sensor is influenced by the temperature of the passenger compartment and fed into the electronic system of the push-button switch unit.
Location of aspirator blower (14) for in-car temperature sensor
An aspirator blower (14), which is connected to the sensor by a hose and runs with the ignition switched on, provides continuous air flow past the in-car temperature sensor. This increases the accuracy of temperature control inside vehicle.
Ambient sensor and temperature sensor for air conditioning
Location of ambient sensor (2) and temperature sensor air conditioning (3)
The ambient sensor (2) is located on the top of the evaporator housing. The sensor transmits its resistance value under influence of outside temperature into the electronic system of push-button switch unit.
The temperature sensor air conditioning system (3) is located in evaporator housing. It senses the evaporator rib temperature and transmits its resistance into the electronic system of the push-button switch unit,
NOTE: These temperature sensors have a negative temperature coefficient (NTC) of resistance, allowing the sensor resistance to decrease with increasing temperature. For testing of temperature sensor refer to "Testing System With Socket Box, Volt and Ohmmeter, and Remedies" Testing and Inspection
Feedback potentiometer for flap position
Location of feedback potentiometer for flap position (4)
The feedback potentiometer for flap position (4) is located on top of heater box. It is actuated by the vacuum element (37) together with the blend air flap.
The quality of the temperature control depends on the adjustment of the feedback potentiometer for flap control, particularly during the cooling mode. For testing and adjusting refer to "Testing System With Socket Box, Volt and Ohmmeter, and Remedies" Testing and Inspection
E. Vacuum elements and switchover valves
There are 3 vacuum elements on the heater box, of which 2 vacuum elements (38 and 39) actuate the air flaps at top and bottom and 1 vacuum element (37) actuates the blend air flaps.
Location of vacuum elements for blend air flaps (37) and defroster nozzle flaps (38)
Without vacuum of vacuum elements (37 and 38) the defroster nozzle flaps are opened and the blend air flaps are in position "full heating".
Location of vacuum element for legroom flaps 139) and fresh air/recirculating air flap (40)
Without vacuum to vacuum elements (39 and 40) the legroom flaps are closed and the fresh air/recirculating air flap is in the fresh air mode position.
Location of vacuum element (41) with heater valve
The vacuum element (41) with heater valve is located below the air intake grille next to the evaporator housing. The heater valve is actuated by the vacuum element (41).
With vacuum applied, the heater valve is "closed"; without vacuum the heater valve is "opened" (refer to vacuum diagram, section B). Vacuum and Vapor Hose Diagrams
Switchover valves
Location of switchover valves
11 Switchover valve strip, 4 connections
12 Switchover valve strip, 5 connections
The switchover valves for the vacuum elements, comprising 2 units, switchover valve strip (11) 4 connections and switchover valve strip (12) 5 connections, are located one above the other under instrument panel, right.
F. Recirculating pump for hot water
Location of recirculating pump (13)
The recirculating pump is located in the return flow of heating water circuit and is running continuously along in heating mode.
As soon as no more heat is required, i.e. when the blend air flaps and the heater valve are closed, the electronic system in push-button unit disconnects the recirculating pump. The recirculating pump is also disconnected during push-button (mode) selection "Vents Closed"
G. Evaporator housing with evaporator and fresh air/recirculating air flap
34 Evaporator housing
a Evaporator tube
b Fins
C Condensate water drain hose left (right side mirror image)
d Fresh air/recirculating air flap
e Condensate water tray
40 2-stage vacuum element
The 6-row evaporator with 6 inlets and its housing is located in component compartment, between front wall and bulkhead.
The fresh air/recirculating air flap (d) and the 2-stage vacuum element (40) for the fresh air/recirculating air flap are located on the evaporator housing.
The evaporator tubes and the fins are made of aluminum (a).
H. Blower switch and blower motor
Location of blower switch (15)
The blower motor is controlled by the 4-speed blower switch. If the speed control lever is against the lefthand stop, the blower motor runs in 1st speed, when one of the push-buttons is pressed:
The blower can only be switched off with button "Vents Closed"
Location of blower motor (8)
A radial blower with two fan wheels (four flow) and 123 mm fan diameter is used as blower motor The power input in 4th blower stage and 13 V battery voltage amounts to approx. 21 amps.
J. Refrigerant (air conditioning) compressor
The diesel engine has a swash plate refrigerant compressor, made by Nippondenso.
Vehicles with gasoline engine up to model year 84 have a Delco R 4 refrigerant compressor and starting model year 85 the Nippondenso compressor. The filling capacity of air conditioning system is 1.1 kg refrigerant R 12 on both models.
Location of refrigerant compressor (143) Nippondenso on engine 601
Location of refrigerant compressor (143) Delco R 4 on engine 102 up to model year 84
Location of refrigerant compressor (143) Nippondenso on engine 102 starting model year 85
K. Function and components of compressor cutout
General information
On engine 601 starting model year 84 and on engine 102 starting model year 85 the accessories and therefore the refrigerant compressor are driven by one common V-belt. To ensure continued operation of the accessories in case of a jammed refrigerant compressor the compressor's electromagnetic clutch is switched off by a control unit.
Components of compressor cutout
1. Rpm sensor
2. Control unit
3. Microswitch
(on vehicles with automatic transmission only)
1. Rpm sensor
Location of rpm sensor for refrigerant compressor (144)
The rpm sensors are measuring the rpm of the engine and the refrigerant compressor. They consist of a magnetic core and a coil. When the ring gear or shaft of refrigerant compressor rotates, an alternating voltage is induced in coils of rpm sensor, which is used as an input signal to the control unit.
Location of rpm sensor engine 601 on ring gear of flywheel (132)
The alternating voltage and thereby the frequency increases or decreases depending on rpm.
NOTE: The engine speed of model 201.024 is picked up from terminal TD on line connector of diagnosis plug.
2. Control unit for compressor cutout
Location of control unit for compressor cutout (141)
The control unit compares the two speeds (rpm) of engine and refrigerant compressor and will cut out the refrigerant compressor at a difference in speed of approx. 30 %.
3. Microswitch on model 201.122 with automatic transmission only
Location of microswitch (134/I) only connected on vehicles with automatic transmission
At engine speeds between 1050 and 2150 rpm (/min) with full load, the compressor is cut out by the microswitch via control unit (141) for improved moving-off conditions (improved low engine speed performance).
Functional description of compressor cutout
If the ignition and the air conditioning are switched on and the engine is not running, the refrigerant compressor remains switched off.
After starting the engine on vehicles up to model year 84 the refrigerant compressor is activated by the control unit (141) as from an engine speed of approx. 500 rpm.
On vehicles as from model year 65 the refrigerant compressor will be activated only after approx. 10 seconds as soon as an engine speed of approx. 600 rpm has been attained (to stabilize the engine speed).
The control unit compares the two speeds of the ring gear and the refrigerant compressor 2 seconds after the compressor comes on (to compensate for clutch slippage during cut-in). It there is an rpm difference of more than 30 % as soon as the compressor comes on, this condition is checked for a period of 200 milliseconds. If the rpm difference equalizes within 200 milliseconds, the compressor remains engaged. If the rpm difference remains (i.e. due to a lammed compressor) the control unit will immediately cut out the compressor. This process is again repeated when the ignition is switched off and the engine is restarted.
To prevent thermic overloading of engine 102, the refrigerant compressor is switched off at approx. 110 °C coolant temperature by temperature switch (23), by switching to ground, via control unit (141) The temperature switch opens at approx. 103 °C and the refrigerant compressor is again on.
On model 201.122 with automatic transmission the refrigerant compressor is switched off at full load at approx. 1050 rpm engine speed. After attaining an engine speed of approx. 2150 rpm the refrigerant compressor is again switched on. If the accelerator pedal is released before an engine speed of 2150 rpm is attained, the control unit will immediately connect the refrigerant compressor. This will improve moving-off conditions of vehicle.
L. Expansion valve and lines
Location of expansion valve (82) on evaporator housing
The expansion valve is similar to the block valve used on models 123 and 126, with a cooling capacity of 6.9 kW (6000 kcal/h).
M. Condenser, auxiliary fan and receiver drier
Location of condenser (63) and auxiliary fan (21)
The condenser (63) is attached to a rubber mount on radiator supporting frame. On model 201.122 it has a block depth of 22 and on model 201.024 of 26 mm. Its tubes having a diameter of 8 mm are made of aluminum. The condenser has a dual flow system, i.e the refrigerant vapor flows through two parallel lines (arrows).
All models with air conditioning system have an electric auxiliary fan.
Location of receiver drier and pre-resistor (18) for auxiliary fan
19 Pressure switch for auxiliary fan
22 Pressure switch, refrigerant compressor a Vacuum valve
a Vacuum valve
The auxiliary fan is activated for one by the pressure switch (19) in receiver drier, via relay (17) and via pre-resistor (18). In parallel with pressure switch, the auxiliary fan is directly activated by the temperature switch 100°C (16) on engine via relay (20).
Location of relay (17) for auxiliary fan via pre-resistor (18)
Location of relay (20) for auxiliary fan
Location of temperature switch 100 °C (16) for auxiliary fan on engine 102 up to model year 84
Location of temperature switch (16) 100 °C for electromagnetic clutch engine fan and 110 °C for auxiliary fan on engine 102 starting model year 85
Location of temperature switch 100 °C (16) for auxiliary tan on engine 601 up to model year 84
Location of temperature switch (16) 100 °C for electromagnetic clutch engine fan and 110 °C for auxiliary fan on engine 601 starting model year 85