1993 mustang LX heating problem

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  #1  
Old 12-03-06, 06:29 AM
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1993 mustang LX heating problem

the temp indicator in my dash indicates that the motor doesn't reach the normal operating temperature. This is happening when the car is in movement. On the other hand, if the car doesn't move, the temperature will be reached, but it will drop once I move fast. In addition, when the indicator says the motor isn't hot enough, there's no heat at all that comes from the ventilation. Heat will be back when I let the car run without moving and let the temp reach normal status. , when it's not freezing,I have replaced the thermostat,pressure cap,antifreeze,coolant flow is good,but still takes forever for engine to get to temp,then cools down when moving
 
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Old 12-03-06, 07:36 AM
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You may have a bad/clogged heater core. Try backflushing the heater core from the engine bay. (the two coolant hoses going into firewall).
 
  #3  
Old 12-03-06, 09:39 AM
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start with a thermostat.........If this is a 4 cyl be sure the bypass hose opening is clear when you have the T/Stat housing off........
 
  #4  
Old 12-04-06, 03:25 AM
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reply from megahertz

Originally Posted by megahertz View Post
the temp indicator in my dash indicates that the motor doesn't reach the normal operating temperature. This is happening when the car is in movement. On the other hand, if the car doesn't move, the temperature will be reached, but it will drop once I move fast. In addition, when the indicator says the motor isn't hot enough, there's no heat at all that comes from the ventilation. Heat will be back when I let the car run without moving and let the temp reach normal status. , when it's not freezing,I have replaced the thermostat,pressure cap,antifreeze,coolant flow is good,but still takes forever for engine to get to temp,then cools down when moving
Thanks for the replies,but the weird thing is that the heat will blast you out when the engine gets to temp at idle,but when you drive off the engine temp drops and so does the heater temp
 
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Old 12-04-06, 11:59 AM
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Then your thermostat is busted allowing the coolant to just stay in the radiator instead of circulating through the motor.
 
  #6  
Old 12-04-06, 04:03 PM
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double check thermostat

Just because you replaced thermostat does not mean you got a good one. Quality has been going downhill on car parts latley might be because of were they are made.
If you want remove it and stick it in a pan of boiling water and see it open then remove and stick in a glass of ice water it should close.
Dont use your wifes best pan or she might say something.
 
  #7  
Old 12-05-06, 10:07 AM
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still heater problem

OK,if the new thermostat is busted just like the new one,what has me confused is that if I let the engine sit idling from cold for an hour the engine temp reaches a level where there is sufficient heat from the heater,but after about 30 min.of driving the engine temp drops and so does the heater temp.Do you think that if the fan runs non stop,this might be cooling this little engine too much? BTW thanks for the replies,I'm getting new ideas to try!
 
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Old 12-05-06, 11:39 AM
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With the vehicle being driven, he cold air will cool the coolant down to where it does not provide heat.

The fan should only turn on when the motor/coolant reaches a hot temp.

It would also be a good idea to flush the system to make sure there are no air pockets.
 
  #9  
Old 12-05-06, 03:44 PM
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thats right

The radiatiotor is just a big heat exchanger with cold air blowing thru it at 55 or whatever heat is drawn off fast. Fan will only run when (1) temp in engine gets past a preset temp. (2) you turn on the air conditioner.
 
  #10  
Old 12-06-06, 08:02 AM
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Question still no heat

Aslong as car does not move the heater output is fine.Once in motion the engine temp drops,so does the heater output.Changing thermostat made no difference,flushed system and replaced coolant.Put old thermostat in boiling water and it opened fine at 190o.The other morning I let the car idle for an hour,before leaving for work,the heater was putting out just fine,after 30 min.driving time (40mph) heater temp dropped off along with engine temp and was just barely warm
 
  #11  
Old 12-06-06, 07:14 PM
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I agree with HotinOKC about the stuck thermostat.

Or MY theory is you have a too cool thermostat.
If the stat is too cool it is not likely to rise above that temp.
Go with the factory temp rated stat.

What temp thermostat do you have ?
I believe it should be a 192 degree stat ? But you should verify that. I'm just going from memory.

Does your radiator fan run all the time ?
If it does, the relay could be stuck in the contact postition preventing the fan from shutting off.

Check the lower hose after driving around for a while, it should be realy hot.
Then feel the upper hose, it should also be hot, then feel the heater hoses they should be as hot as the lower hose. If they are not your heater core is clogged or your deverter valve is bad.

A temporary fix, put a piece of cardboard in front of your radiator.
That's what the 18 wheeler's do.

Something else to think about.
If your temp drops below a pre-determined temp, the engine's computer will cause the fuel system to run rich ( thinking it's still in warm-up mode )and cause bad fuel economy and make it run poorly.
Also check your connector and harness at the thermostat it could be bad.
 

Last edited by Mackey; 12-06-06 at 07:31 PM.
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