MICHIGAN MECHANIC EXAMS SCRIPT QUESTIONS AND
SOLUTIONS RATED A+
✔✔Purpose of a compressor - ✔✔Low pressure gas enters and high pressure gas
leaves
✔✔Symptoms of a failing compressor - ✔✔Pressures are going to be equal
✔✔Purpose of a condenser - ✔✔Low pressure gas enters and high pressure gas
leaves
✔✔Symptoms of a failing condenser - ✔✔Symptoms of failure or restriction are a high
high-side discharge of pressures
✔✔Purpose of a evaporator - ✔✔Low pressure liquid changes into low pressure gas
✔✔Symptoms of a failing evaporator - ✔✔Symptoms of a failed component could be a
leak, sniffer test required
✔✔Purpose of a fixed orifice tube - ✔✔High pressure liquid enters, low pressure liquid
leaves
✔✔Symptoms of a clogged orifice tube - ✔✔Frost forming around the restricted area
✔✔Typical cause of a clogged orfice tube - ✔✔A clogged orifice tube is typically caused
by compressor failure
✔✔R-12 background - ✔✔R-12 is Freon and it destroys the ozone layer due process of
releasing CFCS into the air
✔✔What replaced R-12 - ✔✔R-134a
✔✔What replaced R134a - ✔✔R1234yf
✔✔What is operating pressure of low side pressure? - ✔✔Low pressure should be
between 20psi-40psi
✔✔What is operating pressure of high side pressure? - ✔✔High pressure should be
between 170psi-230psi
✔✔Effect of moisture in the system - ✔✔Moisture in the a/c system will turn to acid and
destroy all the components in the system
SOLUTIONS RATED A+
✔✔Purpose of a compressor - ✔✔Low pressure gas enters and high pressure gas
leaves
✔✔Symptoms of a failing compressor - ✔✔Pressures are going to be equal
✔✔Purpose of a condenser - ✔✔Low pressure gas enters and high pressure gas
leaves
✔✔Symptoms of a failing condenser - ✔✔Symptoms of failure or restriction are a high
high-side discharge of pressures
✔✔Purpose of a evaporator - ✔✔Low pressure liquid changes into low pressure gas
✔✔Symptoms of a failing evaporator - ✔✔Symptoms of a failed component could be a
leak, sniffer test required
✔✔Purpose of a fixed orifice tube - ✔✔High pressure liquid enters, low pressure liquid
leaves
✔✔Symptoms of a clogged orifice tube - ✔✔Frost forming around the restricted area
✔✔Typical cause of a clogged orfice tube - ✔✔A clogged orifice tube is typically caused
by compressor failure
✔✔R-12 background - ✔✔R-12 is Freon and it destroys the ozone layer due process of
releasing CFCS into the air
✔✔What replaced R-12 - ✔✔R-134a
✔✔What replaced R134a - ✔✔R1234yf
✔✔What is operating pressure of low side pressure? - ✔✔Low pressure should be
between 20psi-40psi
✔✔What is operating pressure of high side pressure? - ✔✔High pressure should be
between 170psi-230psi
✔✔Effect of moisture in the system - ✔✔Moisture in the a/c system will turn to acid and
destroy all the components in the system
