I have tried the dealership 3 times and have not been able to get the rear heater to work properly. When the vehicle is moving I have heat but if I slow or stop the heat goes away. I believe it only happens to the rear heater as front feels fine.

 

You need a full flush.....I'll bet dollars to donuts it's clogged up. What are your deltas?

 

Do you have heat up front?

 

How good is your thermostat? You may need a new one, if it is sticking open, water won't be hot enough to the back heater unless generating heat in the motor. Change the tubing to the back heater, they can collapse from the inside and restrict flow.

 

Unfortunately I am not the best mechanic. I see a few things I have to check. The front does get plenty of heat but I will check it again. I know its not the thermostat as I recently changed it thinking that was it. I have to figure out where the hose is and change it as I can see 10 years old it might be soft and collapsing. Thank you for these suggestions. If you have any pics as to where I should start looking I can make it happen faster.