When my 1999 jeep grand Cherokee is driving the heater blows hot air when driving but when it idles it blows cold air even though the engine is warmed up, any ideas?
Sounds like you may have a partially plugged heater core. You could flush this out separately, from flushing radiator & engine block. Diconnect heater hoses going to your heater core and clamp off, so not to loose coolant from engine. Now hook up separate hose to one side of heater core pipe and flush out with typical garden hose. Repeat procedure on both heater core inlets. Reconnect original heater hoses and test difference. You may have to add an additional litre of antifreeze. If this don't work i suggest changing heater core. Good luck.........Ron.
Symptoms: heater blows hot while driving/higher rpms but blows considerably cooler when at idle.
If you do not know the last time you had your heater core flushed, then it is long overdue,,,try this first. Cheap and easy to due, or about 75 bucks to have it done at your local shop. You will be amazed at the crud that will come out. This is the stuff that plugs your heating system. You should notice the difference immediately.
Symptoms: heater blows hot while driving/higher rpms but blows considerably cooler when at idle.
If you do not know the last time you had your heater core flushed, then it is long overdue,,,try this first. Cheap and easy to due, or about 75 bucks to have it done at your local shop. You will be amazed at the crud that will come out. This is the stuff that plugs your heating system. You should notice the difference immediately.
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Replace the thermastat with a higher temp rating, but first make sure that the fluid level is optimal,....low fluid will cause this,,,as will an old thermastat
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2008 Mustang...cold air comes from vents when heater is on. If car runs for a while, eventually the air will warm up. Could take up to 20 minutes for this to happen. And, seems to happen after RPMs get up to a certain number. Any ideas?
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