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My 2004 Jeep Grand Cherokee with 6 cyl engine has no heat. Car warms up and operates at normal temp but heat just blows cold. Fan works - any Idea what I can check.
If jeep is a limited model it has automatic temp control for the heater blend door, it is controled by a electric motor, and can be problematic with age,sometimes it makes a clicking noise when the blend door is stiff ,which then it must be lubed and freed up
Either the heater core is plugged or partially plugged, the heater control valve is not opening completely or the thermostat isn't allowing the engine to warm as much as it should. Even though the engine seems warm enough, if the thermostat isn't working properly you may not be all the way up to temperature.
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If your "check engine" light is turn on, I suggest scanned the PCM to know exactly what fault code is stored there. Additionally, could be some problem with the "temp sending unit".
Two reasons that the temp won't come up...Most common is that your thermostat is stuck open. There are tests to check that but the stat is inexpensive and relatively easy to replace. Use a 195 degree (f) and make sure that you put the new one in the same way the old one came out (spring end into the engine) make sure all gasket material has been removed or it will leak and use 50/50 mix of coolant to replace any lost while working. (system does not need to be drained to do that job but you will loose some) re-fill with heater on full heat, engine running. The other possibility is that your electric fan is always on. If the fan is running with the engine cold, replace the relay (usually found behind and below R/F headlight, accessible from under vehicle with a little work.)
Be careful, with engine at normal oper. temp. feel both upper and lower radiator hoses, they should both feel the same, warm to hot, if not the same temp. replace the thermostat.Heat sensor either work's or not, if it reads hot, engine is hot, or will not work at all.
After warmup it still blows cold, or only when cold? Normally the fan will operate independently of engine temp except in some climate controlled vehicles. As long as it blows warm air after engine is at temp that's a good thing. the heater uses hot water from the engine. Obviously the heater can't be warm before the engine is. If it's cold after the engine is hot, there are vacuum controlled "motors" on top of the heater box under the dash that move doors that control heat. Either one of the control motors or one of the doors have stuck or failed. Many also have a control valve on one of the heater hoses under the hood as well. If the engine comes up to temp then the thermostat is good (should be at about 210f) Only remaining item is the core itself which may be internally or externally obstructed. All this being said, if it's good when the engine is up to temp, leave it alone...it's fine.
1st, what is 'heater treater?' Is this something you add to the cooling system? Is your engine temp gauge in the normal range, or is the jeep running at the cold end of the temp. gauge? Is the fan for the heat/and a/c working? There are several reasons you may not have heat. 1.make sure coolant level is ok, low level will cause a no heat condition.2. If engine is not warming up properly (running at the cold side of temp gauge), you may have a thermostat that's stuck open, not allowing the engine to reach operating temp-result, no heat.3. If you can hear the fan blowing for the heat-a/c, but not feel it blowing at the vents, your 'blender door' (opens and closes to allow heat-a/c to enter the cabin) may be stuck closed. I had a Jeep (4L engine, but older than yours) which had a valve in the heater hose line that once froze up (stuck closed) and resulted in a no heat situation. If the heater treater is something you add to the radiator, I wouldn't waste the $ to use it, as it probably won't help this problem. Your codes: I could find no code 54, #14 is 'B' camshaft position sensor -timing over advanced, or system performance bank 1.
Usually the electric fan(s) are temperature activated. I would look into the temp switch. If you're not sure what it is, go to the auto parts place and ask for one. This way you can look at it then hunt for it under the hood. It usually screws into the engine in the cooling system. Also, make sure the fan has a good ground. Check for power to the fan when the engine warms up. If you have a/c, turn it on and the fan should come on whether the engine is warm or not.
ENGINE STALLS UPON SLOWING DOWN OR AT FULL STOP
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