I have a 2007 Camry and when you apply the brakes or even stop accelerating the heat turns cold. I have replaced the water pump and it is not low on antifreeze. I saw something about a vacuum line but cant find the article anymore. Does anyone know about this vacuum line or what you think could be wrong. Also not showing any of the five signs of heater core not working properly.

 

What engine V-6 or 4 cylinder?

Who replaced the water pump? Was the thermostat changed?

Have you removed the radiator cap (engine cold) and checked the coolant level. Bleed the system of air?

Are the left/right air outlets putting out the same hot/cold air?

Any change in coolant temperature gauge needle?

 

It is a 4 cyl. I replaced water pump and thermostat. The vents seem to be putting out the same amount, warm when driving and cool when out of gas or on brakes and the thermostat needle never gets above mid range

 

Have you removed the radiator cap (engine cold) to check the level. Air in the coolant system can cause this problem.

Feel the two coolant lines that go to the firewall (heater core fluid in/out) when engine hot. They should be hot.

The heater system does not have a coolant valve on a hose to control coolant flow to set air temp. This is done by the air/mix door.

The hot/cold is set by the air mix door. The electric servo for the door is on the passenger's side of the AC/heater box.

The servo moves an arm up/down to let more hot or cold into the air mix to control temperature. Find the servo and determine if it works. The arm being up is hot, down is colder air.

Any chance of mice building a next in the heater core area that would block the flow of air?

If the climate system is automatic. There would be temp sensor for setting the air mix temp. The sensor can fail.

 

I have noticed that the passenger side air is not as warm as the drivers side. What could be causing this

 

Have you checked any of the items in the previous post?

 

I have checked everything but the servo. No air in radiater. The lines going to heater core are hot and no mice

 

Check if the servo arm (blend door actuator arm) moves with the selected temperature.

The blend door arm being approx at a 45 degree position up may be full hot and 45 down full cold. Can always remove servo and manually move door full hot. Then determine is still have the problem.

If you have checked every else out. Suggest flushing out the heater core with a garden hose.