Heater not working

Tiny
SWEETSMACK55
  • MEMBER
  • 2002 MERCURY SABLE

My heater will blow warmish air when it is first turned on after the car has warmed up. Within a minute or 2 it starts blowing out cool air. I have flushed out the cooling system all ready. It is not dripping water anywhere (as it would for a heater core problem). A mechanic told me it sounded like it might be a issue with the blend door. Does this sound right, and if so is this something I could fix myself?
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Thursday, February 25th, 2010 AT 7:22 PM

17 Replies

Tiny
RASMATAZ
  • MEMBER
Check and test the thermostat and heater control valve if both okay could be one of the following-air mix/blend/mode door problems, vacuum and actuators to include the HVAC control module

Heres a guide on replacing a blend door actuator. Not vehicle specific, but it will give you an idea of whats involved

https://www.2carpros.com/articles/replace-blend-door-motor

Attached below you will find the diagrams to replace the blend door actuator fro your vehicle
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Thursday, February 25th, 2010 AT 7:33 PM
Tiny
ELGRECO
  • MEMBER
  • 2002 MERCURY SABLE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 11,000 MILES
I tried this morning and there is no heat being generated. This is a sudden problem.

Thank you
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Monday, December 24th, 2018 AT 12:05 PM (Merged)
Tiny
MERLIN2021
  • EXPERT
Heater Core " Plugged

WARNING: The heater core inlet hose will become too hot to handle if the system is working correctly.

Check to see that the engine coolant is at the correct level.
Start the engine and turn on the heater.
When the engine coolant reaches operating temperature, feel the heater core inlet and outlet hose to see if they are hot.
If the inlet hose is not hot:

the thermostat is not working correctly.
If the outlet hose is not hot:

the heater core may have an air pocket.
The heater core may be restricted or plugged.
If both are hot, the temperature blend door in the heater plenum may be broken or stuck.
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Monday, December 24th, 2018 AT 12:05 PM (Merged)
Tiny
GLEN35
  • MEMBER
  • 2002 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 122,380 MILES
I have a 02 mercury sable and the heat quit working. It started last week when it was going in and out. The blower sounded strong. It just quit blowing like it had a short in it. What do you think?
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Monday, December 24th, 2018 AT 12:05 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
If the blower motor is cutting out, check the wiring to the motor to make sure it is tight, clean, and not damaged. If it is good, check to see if it gets continuous power while moving the wiring around. If it does, chances are the motor is going bad.
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Monday, December 24th, 2018 AT 12:05 PM (Merged)
Tiny
RMOELKE
  • MEMBER
  • 2002 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 160,000 MILES
The heater in the car does not blow heat. Thermostat has been changed. Heater core flushed. Does it sound like a new heater core is needed or could it be something else? If it is the core is it a bix fix?

Thanks
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Monday, December 24th, 2018 AT 12:05 PM (Merged)
Tiny
BMRFIXIT
  • EXPERT
Check coolant level
Is the car reaching operating temp
Check heater core hoses if both are hot,
if yes then suspect and check the blend door actuator
if not the heater core need to be flushed again as a 1st step
these are the steps
Warning: never remove the pressure relief cap under any conditions while the engine is operating. Failure to follow these instructions could result in damage to the cooling system or engine and/or personal injury. To avoid having scalding hot coolant or steam blow out of the cooling system or degas bottle, use extreme care when removing the pressure relief cap from a hot cooling system or degas bottle. Wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly until pressure begins to release. Step back while the pressure is released from the cooling system. When certain all pressure has been released, press down on the pressure cap (still with a cloth), turn and remove pressure relief cap.
Engine cool
lower the coolant level
Locate the two hoses running to the heater core
disconnect them at the engine side leaving hoses connected to heater core throw the firewall
use garden water hose and compressed air if possible
run the water and follow by air throw one side and out the other and vice versa
do that two to three times watching what leaving the heater core you are looking for the good flow and clear water to run throw
reconnect hoses
top off coolant system
good luck
let me know
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Monday, December 24th, 2018 AT 12:05 PM (Merged)
Tiny
DYHILL
  • MEMBER
  • 2002 MERCURY SABLE
2002 mercury sable-fan blows cold air when heater is all the way over for hot. Thermastat has been replaced and there are no leaks. How should this be taken care of?
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
Check the heater core, heater control valve and the air blend door-
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
ITCRMC
  • MEMBER
  • 2002 MERCURY SABLE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 165,000 MILES
1. I researched and there is a TSB on this from Ford for the Blend Door Binding or Sticking.

2. I purchased a blend door from Ford for $6.00.

3. I looked at the blend door and all Ford did was cut a piece of the rubber seal off to prevent it from binding or sticking, so instead of breaking the air unit apart to replace the door, I cut the seal with a razor blade.

4. Still no heat after reassembly.

5. The next day I flushed the cooling system. I know, should have done this first. I measured the output of the heater at 150 degrees after the flush.

6. Replaced with fresh coolant. Heater worked fine.

7. Got in the car this morning and no heat.

My question:

I worked on the car in a shop that was heated. Is it possible that once the blend door warmed up, it worked fine, but when I let it sit overnight in 20 degree temperatures, the door is less pliable and then binds? It's either that or the blend door actuator is not working. Just want a second opinion.

Thank You!

Kevin
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
BMRFIXIT
  • EXPERT
This is the Check list for no heat
if you go through it, it should show when is the problem
I would assume its a heater core that need to be isolated and flushed

Check coolant level
Is the car reaching operating temp (if not or engine taking long time to reach operating temp suspect and replace thermostat )
Check heater core hoses if both are hot,
If both hoses hot and not enough heat inside suspect blend door actuator
If one hose hot and the other warm or cold the heater core need to be flushed (very common)
as a 1st step
these are the steps
Warning: never remove the pressure relief cap under any conditions while the engine is operating. Failure to follow these instructions could result in damage to the cooling system or engine and/or personal injury. To avoid having scalding hot coolant or steam blow out of the cooling system or degas bottle, use extreme care when removing the pressure relief cap from a hot cooling system or degas bottle. Wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly until pressure begins to release. Step back while the pressure is released from the cooling system. When certain all pressure has been released, press down on the pressure cap (still with a cloth), turn and remove pressure relief cap.
Engine cool
lower the coolant level
Locate the two hoses running to the heater core
disconnect them at the engine side leaving hoses connected to heater core throw the firewall
make sure you pinch and close the bypass hose between the two heater hoses
use garden water hose and compressed air if possible
run the water and follow by air throw one side and out the other and vice versa
do that two to three times watching what leaving the heater core you are looking for the good flow and clear water to run throw
reconnect hoses
top off coolant system
good luck
let me know
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
MLNELSON232
  • MEMBER
  • 2000 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 128,000 MILES
My car has no heat at all----when you turn on the heat you can smell coolant it is freezing here and the moisture from the heater has caused my windows to ice up (i was runing the heater to try to unfog the windows it only made it worse)----Also my car is overheating it over heats when you are driving slow (like at a stop or stuck in traffic) a back yeard michanic said heads and somone else said it could be a heater core How could I know which is the problem? Is there any extra signs for the two? Please let me know asap ---- I have a 1999 mercury sable
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
Hi
The smell and window icing tell me heater core leaking. If coolant is low that would cause your overheating. Assume it is cold where you live. Do you see white smoke a water comming from tail pipe? Doea oil look normal or a little like chocolate malt? Yes to either question head gasket failure.
Let me know
Merry Christmas
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
MLNELSON232
  • MEMBER
Let me add some more details----I have replaced the radiator and the thermostat because I bought the car and the radiator was rusted and leaking I also had to replace the thermostat due to rust----the mechanic I had look at it told me the heads are bad but I the oil is not milky and the car doesnt overheat all the time only when the car is at a stop and when you are in slow traffic and not moving over 5mph I went somewhere else a second opinion told me that the cause of the overheating was from the heater core being out, and everything else was fromt hat also---symthoms the car is overheating, when you turn the heat on no heat and it smells like antifreeze, it is winter and of course my inside windows iced up and there is leaking under the passenger side dash it is not bad just a little. If it is the heads I am not fixing the car thats going to cost more than the car is worth because there are a few other small issues----I need to know the tell tale signs between heads or heater core----thanks
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
O.K. Heater core leaking will not cause car to overheat It will if coolant is run low.
If headgaskets are faulty and leaking that will cause car to overheat.
Over heating at low speeds can be caused if cooling fans are not operating. Verify they are operating.
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
PDLSTRATE
  • MEMBER
  • 2004 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 93,000 MILES
Had blend door acutuator replaced 3months ago. Now there is flucuating heat from no heat to a little. The temp gage fluctuates as well. Check engine lite is now on. I do smell antifreeze the the car while driving as well. Don't know where to look first. Thanks.
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Monday, December 24th, 2018 AT 12:06 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
Replace the thermostat and inspect and test the heater control valve and also the heater core.
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Monday, December 24th, 2018 AT 12:06 PM (Merged)

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