What causes heater to run cold when Elantra stops? Ask the Car Doctor

My 2006 Hyundai Elantra’s heater runs perfectly at road speeds but quickly turns cold when stopped at red lights or when idling.
San Diego Union-Tribune

Replacing RAV4 heater core is a terrible job

My brother has a 2006 Toyota RAV4 with 125,000 miles, which we think has a clogged heater core. The Toyota maintenance schedule calls for changing the coolant every 100,000 miles, which he has done.
Dayton Daily News

CAR TALK: Bypassing a heater core it is a piece of cake

Dear Car Talk: I have a “no heat” problem on my ‘99 Pontiac Grand Prix SE 3.9 liter. It runs fine with no overheating (yet). I suspect a plugged heater core and want to bypass it for the rest of the ...
Northwest Arkansas Democrat Gazette

CAR TALK: Try these ideas before a ‘no heat’ problem becomes a real problem

DEAR CAR TALK: I have a "no heat" problem on my '99 Pontiac Grand Prix SE 3.9 liter. It runs fine with no overheating (yet). I suspect a plugged heater core and want to bypass it for the rest of the ...
The Republic

Try these ideas before a ‘no heat’ problem becomes a real problem

I have a “no heat” problem on my ‘99 Pontiac Grand Prix SE 3.9 liter. It runs fine with no overheating (yet). I suspect a plugged heater core and want to bypass it for the rest of the summer. Will ...