This part of site is an attempt to organize and add to the web resources for the Rover SD1
to form a cohesive and easily usable guide for those of us without easy access to
expert repair and/or advice. It is not offered in any way as a definitive source
and we take no responsibility for any errors that may exist.
Webmaster Rene Winters
The Rover SD1 Airconditioning |
To begin this section we are going to look at the refrigeration system fitted to the
Rover. The Triumph TR7 system comprises the Compressor 1, the condensor 2, the
receiver/dryer 3, the expansion valve 4, and the evaporator 5.
The V.I.R. Unit |
On the Rover SD1 the receiver/dryer and the expansion valve are replaced by these valves in
receiver or V.I.R. unit.
Liquid refrigerant from the condensor enters the V.I.R. unit through port C and
passes into the storage reservoir H, where a sack of desiccant crystals F, will
absorb a limited amount of moisture, but beware this amount is very small.
The refrigerant leaves the reservoir via pick-up tube G, which is fitted with a filter
screen. Visual inspection of the refrigerant is permitted by a sight glass, E.
The refrigerant passes through the lower half of the thermostatic expansion valve J,
where its pressure is reduced, and then through port B, to the evaporator.
Warm gaseous refrigerant, leaving the evaporator, returns to the top of the V.I.R. unit,
via port A and from here to the compressor, via port D. The suction throttling valve K,
regulates the flow in terms of optimum evaporator pressure and compressor suction.
This ensures that the evaporator operates at maximum efficiency and does not freeze up.
System Operation |
In this section we are going to look at how the Rover SD1 air conditioning unit
works and how it is controlled.
First let's see how it works. This blower unit, located behind the passenger's glove box,
provides an airflow.
A flap, on its casing enables fresh or recirculated air to be selected.
Air from the blower box enters the conditioning unit through inlet 1,
and leaves via a choice of outlets on each side. Outlet 2 supplies cold air only,
to the facia vents. The other outlets supply temperature regulated air; outlet 3 to
the centre face level vent, outlets 4 and 5 to the end of facia and screen vents;
and outlet 6 to the footwells.
On entering the conditioning unit, the air is cooled and dehumidified as it passes over
Airflow through the heater is regulated by this blend flap. The wider the flap is open the
more heat is supplied to the car.
A second flap controls the flow of air from the centre face level vent and this flap at
the base of the unit distributes the output to the screen outlets or to the footwell and
end of facia outlets.
Control of the system is by means of these three levers. On the left is the mode selector.
The centre lever is the on/off switch and the blower fan speed control.
The lever on the right is used to select the in-car temperature.
The levers control the system mechanically, electrically and by vacuum. First let's
consider the vacuum circuit.