stumped!! heat comes and goes

well sometimes i have heat and sometimes(most times)it is ice cold.the temp will go up and down as well.i can get heat for a few min then it goes cold again.
tried raising the car and bleeding the system.tried flushing the heater core also.radiator is new,therostat,and water pump is also.left heater hose is hot to the core and pressurized,and also the top hose on the rad is hot after the car runs and stays pressurized.boils over into the overflow.
does this sound like an air pocket or a bad heater core.i get a full stream through the core when flushing it.no antifreeze smell in the car and no leaks that i can see under the car.no white smoke either.

help would be GREATLY appreciated.thanks

well sometimes i have heat and sometimes(most times)it is ice cold.the temp will go up and down as well.i can get heat for a few min then it goes cold again.
tried raising the car and bleeding the system.tried flushing the heater core also.radiator is new,therostat,and water pump is also.left heater hose is hot to the core and pressurized,and also the top hose on the rad is hot after the car runs and stays pressurized.boils over into the overflow.
does this sound like an air pocket or a bad heater core.i get a full stream through the core when flushing it.no antifreeze smell in the car and no leaks that i can see under the car.no white smoke either.

help would be GREATLY appreciated.thanks




anyone????????

Are you sure the coolant level is correct? You said one heater hose is hot but what about the other one? Is it about the same temp? Is there water in the oil? Did you install a good quality thermostat or a cheapy? You can check the thermostat by putting it in a pan of water on your stove and seeing at what temp it opens.

tbird,i have no water in my oil and everything else seems fine.i did not even think about the thermostat cause i changed it a month ago.i guess it is very possible it is bad already.i did buy it at autozone and they only gave me one choice and it was a cheapy.thanks for bringing that to my attention.it sure does sound like a bad stat.ill try the boiling water.thanks again.

You might want to check the heating controlls themselves. Most are vacume controlled and may "drift" from hot to cold without knowing it.

Hope this helps.

This problem developed in my 90 recently. Cold air no matter what I move. The heater core was replaced about 18 months ago. I've narrowed it down to the control unit. Never delt with vacuum systems though. How do you check the vacuum hoses. Do I just need to replace things until it gets fixed. Anything to be aware of while I work on the system? Thanks

008, Your blend door actuator is probably not working. If the blend door isn't moving to allow air to pass through the heater core then you won't have any heat. See my post for checking climate control diagnostics in the Tech Help thread on page 2.

If your car has the digital climate control unit vs. manual you may have a problem with the sensor that determines the cabin temperature. It is located behind the vent just to the right of the radio and it says "stereo" over the top of it. Fortunately it doesn't require the entire dash removal to get to it either.

I have a '95 and had done without heat for a couple years after the blend door motor crashed and burned. I was too cheap to spend the money to tear the dash out to fix such an inexpensive part, but when the heater core started leaking I bit the bullet and had it all done. After those repairs were complete the dealership started having the same problem as you are describing and found out it was that sensor. Unfortunatley they are not available through Ford anymore and it was never produced as an aftermarket part, so I had to find mine at a salvage yard. They pulled it and charged me $45.00. Not too bad.

Also in case you want to test if it's the entire climate control unit, you can find those at a salvage yard too for reasonable prices. If you purchase one at the dealer and that ends up not being the problem it is non-returnable and the cost here in Texas was close to $400.00! Ouch!! I purchased one at a salvage yard for about $30.00 and it's still going strong.

Hope this helps.

Good luck,

Sarah (sarah95tbird)

well sometimes i have heat and sometimes(most times)it is ice cold.the temp will go up and down as well.i can get heat for a few min then it goes cold again.
tried raising the car and bleeding the system.tried flushing the heater core also.radiator is new,therostat,and water pump is also.left heater hose is hot to the core and pressurized,and also the top hose on the rad is hot after the car runs and stays pressurized.boils over into the overflow.
does this sound like an air pocket or a bad heater core.i get a full stream through the core when flushing it.no antifreeze smell in the car and no leaks that i can see under the car.no white smoke either.

help would be GREATLY appreciated.thanks
headgasket blown - even though no coolant in oil or white smoke, the leak
will get worse causing these symptoms - 3.8 engines are very known for this
problem called ford disease

hey man, I would say also that the head gasket is junk. Very common in the 3.8 fords. I would double and triple check the coolant levels though.