When the engine is at operating temp, feel both the heater hoses (half the diameter of the radiator hose, twice as long, and they both go into the firewall next to each other.) If one is hot, and the other is cold, your heater core is plugged. If they are both hot, the blend door still isn't working. If they're both cold (and the engine is typically running cool), then check your thermostat. Good luck!
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There are several possible reasons why you may be experiencing cool or no heat in your 2002 Jeep Grand Cherokee Laredo after replacing the thermostat and bleeding the air out of the lines. Some possible causes could include:
A malfunctioning blend door or actuator: The blend door controls the mix of hot and cold air that is directed through the heating system. If the blend door or actuator is not functioning properly, it may cause a lack of heat.
A clogged heater core: The heater core is responsible for transferring heat from the engine to the cabin of the vehicle. If the heater core is clogged, it may not be able to transfer heat effectively, resulting in cool or no heat.
A faulty thermostat: If the thermostat was not properly installed or is not functioning correctly, it may cause the heating system to not work properly.
A problem with the water pump: The water pump is responsible for circulating coolant through the engine and heating system. If the water pump is not functioning properly, it may cause a lack of heat.
If after running the engine for 5 min both heater hoses are hot, it could be a blend door problem where air is not flowing thru the heater core. You may need a shop manual to troubleshoot the control.
Good point. Solving it will probably take more time than money.
Thermostats and heater cores do not work one day and stop the next. If your engine warms up normally and doesn't overheat, the gauge reads normally, engine is at normal operating temperature after about 10-15 minutes ...all these point to a good thermostat. It is working right and should not be a problem.
To check the heater core, wait till engine is at normal operating temperature. Turn heat setting to high, then feel both heater hoses-both should be hot. If both are hot the core is circulating coolant and is not a problem. If only one is hot (which would be the inlet hose) the core is not circulating-could be an air block or the core is plugged up and will need replacing.
If heater core and thermostat are good, then it probably is the temperature blend door in the heater case. The door actuator is probably vacuum controlled. I don't know how difficult it is to troubleshoot on your Taurus, but check if vacuum controls are working right from the dash controls, check if the blend door is stuck, is broken, or if the vacuum control is working to open and close the blend door. When you want heat, the blend door should let blower air pass across the heater core.
From the engine you will have a single vacuum hose that goes through the firewall into the dash to the heater/AC controls. There, a pod like device can rout the vacuum signal to various doors on the heater case.
Good luck.
I don't know your vehicle, but does it have a blower door tucked in where the heater core is? If it DOES and that's broken then it could be the whole problem. It would mean it isn't switching from the A/C side of things to the heat side of them. Hope this helps, good luck! Also, just looked up the proper name for what I'm talking about, it's called a "blend door" and I think your car has one. It's what I would check, again, good luck!
Those look to be blend door codes you could try resetting them, does the heater make a clicking sound? If that is so the blend door actuator is bad and needs replacing.
If you have good heat on one side, it can't possibly be the the thermostat. Good heat on one side means that there is plenty of hot water (water and antifreeze mix) circulating through your heater core. The thermostat controls the temperature of the water. If you have hot water, the thermostat is not at fault. Your Impala is equipped with what is called "zoned climate control". All the inside air (both sides) is still heated by the same heater core. The difference between a "zoned" system and a conventional system is that there is more than one "blend-air" door insided your HVAC housing. The blend-air door swings back and forth to direct the incoming air either through the heater core (for hot air) or around the heater core (for cold air) The drivers blend-air door may be broken or the motor that moves the blend-air door is malfunctioning.
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