ASE Heating and Cooling 2

Question 1

A vehicle takes a long time to warm up, the temperature gauge reads low on the highway, and heater output is weak. What is the most likely cause?

Accepted Answer

Thermostat stuck open

Answer

A thermostat stuck open lets coolant flow through the radiator constantly, so the engine runs cold and heat output drops.

Question 2

For each 1 psi of pressure a radiator cap holds, the coolant boiling point rises by approximately how much?

Accepted Answer

3°F

Answer

Each psi of system pressure raises the boiling point about 3°F, so a 15 psi cap adds roughly 45°F.

Question 3

A 50/50 mix of ethylene glycol antifreeze and water gives freeze protection down to approximately:

Accepted Answer

-34°F

Answer

A 50/50 ethylene glycol mix protects to about -34°F.

Question 4

A technician suspects a head gasket leak into the cooling system. Which test directly detects combustion gases in the coolant?

Accepted Answer

Chemical block (combustion leak) test

Answer

A block tester draws air from the radiator through a fluid that changes color when it contacts combustion gases (CO2).

Question 5

A customer reports a sweet smell inside the car, a greasy film on the windshield, and a damp passenger floor. What is the most likely cause?

Accepted Answer

Leaking heater core

Answer

A leaking heater core puts coolant into the cabin, which causes a sweet odor, an oily fog on the glass, and wet carpet.

ASE - Automotive Service Excellence Certified Tech Practice Test