Auto Mechanics Paper 2,May/June 2010  
Questions:   1 2 3 4 5   Main
General Comments

Question 3

The sketch below shows the layout of an automobile air-conditioning system

(a) Identify the parts labelled V, W, X, Y and Z.
(b) State one function of any three of the labelled parts in (a) above.
(c)   Describe the basic principles of operation of an automobile air- conditioning system.


Most of the candidates did not attempt this question due to lack of knowledge.
The few candidates who attempted it could not give the required responses to the various parts of the question. The required responses are given below.

(a) V is compressor
W is evaporator
X is condenser
Y is receiver/drier
Z is expansion valve.
(b) Compressor raises the pressure and therefore the temperature of the vaporized refrigerant.
Evaporator absorbs heat from the passenger area. Condenser cools and condenses the refrigerant under pressure Receiver/drier filters, dries and temporarily stores refrigerant under pressure.

Expansion valve is a controlling device that allows just the right amount of refrigerant to enter the evaporator.
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