No heater? Not working?

Tiny
SPDSPIDY
  • MEMBER
  • 2003 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 65,000 MILES
Car blows cold air changed thermostat and flushed heater core it helped a little now is warm but not hot any ideas?
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Saturday, January 3rd, 2009 AT 2:20 PM

19 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
Hello,

It sounds like the temperature blend door actuator is not working here is a guide to help walk you through the repair and diagrams below to show you how to fix the problem on your car.

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

This guide can help as well

https://www.2carpros.com/articles/car-heater-not-working

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed. Joe
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Wednesday, January 14th, 2009 AT 10:35 AM
Tiny
MIKEANDLYNN
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  • 1 POST
  • 2003 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 78,000 MILES
Wife put gas in car. It started missing almost at once. Engine light came on and there is no heat but fan workes fine. Have had trans trouble for some time. When trans gets hot it slips from 1st to 2nd and over drive is not connecting at all. LOVE THIS CAR but it needs lots of work I guess. Do you think the trans and the other problems are connected? Thought it was head gasket but coolant looks good and no over heating. Was told to tune it up but it did not help. Friend thinks it is a computer board or two. Got any ideas?
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Friday, February 8th, 2019 AT 5:56 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis, finding out what's going on.
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Friday, February 8th, 2019 AT 5:56 PM (Merged)
Tiny
LASHA
  • MEMBER
  • 1 POST
  • 2003 MERCURY SABLE
  • 4 CYL
  • AUTOMATIC
My car heater is not working in my car and my hot, cold gauge is moving up toward hot. I don't know what's wrong I just put anti-freeze in it 1 week ago. What could be causing these problems?
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Friday, February 8th, 2019 AT 5:56 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Thermostat is not opening need to replace
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Friday, February 8th, 2019 AT 5:56 PM (Merged)
Tiny
BARRY J.
  • MEMBER
  • 1 POST
  • 2000 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 112,000 MILES
I have no heat, and the defroster blows only cold air. Also, the defroster "fogs up" the windshield when the car is first started in the morning. The fog goes away after a few minutes.
The air conditioning works fine. The coolant seems to heat up properly (the temperature gauge shows a normal level).
I'm hoping I can solve and fix this problem myself.
Looking for your advice!
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Friday, February 8th, 2019 AT 5:56 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
For a start replace the thermostat could be sticking open.
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Friday, February 8th, 2019 AT 5:56 PM (Merged)
Tiny
SABLEOWNER2003
  • MEMBER
  • 2 POSTS
  • 2003 MERCURY SABLE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 77,000 MILES
My car will not put out heat. When I turn the dial (inside the car) to the first option on the left, the car will put out some warm-to-cool air. If I turn the dial to the right (any option), the car will put out cool air only.

I've tried flushing the radiator; replacing the thermostat; and making sure all the "tubes" (for lack of a better word) are clear and the heater core is working. The heat still won't work. Also, the car is not building up pressure. I've tried replacing the cap on the antifreeze reservoir. Nothing is working.

My "handy man" mechanic thinks the heater control valve (that switches from cold to hot) needs to be replaced. He's trying to find out where this valve is located on the engine.

Can you help?

What do you think seems to be the problem?
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Wednesday, November 13th, 2019 AT 5:07 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Check heater core hoses the two coming from the firewall they should be hot is one is hot and the other warm then you have a clogged heater core and it needs to be flushed
if both very hot then I would suspect blend door motor inside on the HVAC box

THis guide can help

https://www.2carpros.com/articles/car-heater-not-working

It sounds like a mode actuator.

USE NOTES: Change the water pump there was no fins left on the pump to sica let the water changed mine and it works great
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Wednesday, November 13th, 2019 AT 5:07 PM (Merged)
Tiny
SABLEOWNER2003
  • MEMBER
  • 2 POSTS
The heater core has been flushed with the water hoses. The water (antifreeze I guess) is moving smoothly through; both lines are HOT.

The thermostat was replaced and it opens like it's supposed to.

The radiator has been flushed.

We are now concerned with PRESSURE BUILD UP. No pressure is building up under the cap (that's on the antifreeze reserviore).

I tried replacing the cap. No deal.

Any idea why no PRESSURE is building up?

It's very cold here in Missouri.
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Wednesday, November 13th, 2019 AT 5:07 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
If the two heater hoses hot then its the blend door motor stuck on cold
remove and replace blend door motor


https://www.2carpros.com/forum/automotive_pictures/99387_Graphic1_67.jpg

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Wednesday, November 13th, 2019 AT 5:07 PM (Merged)
Tiny
FBURNS7
  • MEMBER
  • 1 POST
  • 2000 MERCURY SABLE
  • 146,950 MILES
I have a 2000 mercury sable 3.0 DOHC, I have to put coolent in the tank often (Once a week). I can't find a leak and there is no heat when I urn the heater on, only cold air. This past summer I replaced the air compresser. It blows cold air, but no hot air now that is's getting cold. Low coolent light comes on at least once a week. Can anyone help.
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
First, if you have to keep adding, it is going somewhere. Try putting a piece of cardboard under the vehicle over night to see if there is any on it in the AM. Next, check to see if there is any coolant getting into the motor oil. It will make a lite brown creamy substance. Finally, with the engine hot, the heater on high, feel both heater core hoses. Both should be hot. If only one is hot, flush the core. If they are both hot, check the blend air door near the heater core. It is responsible for allowing heat to enter the vehicle.
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
DAWN108
  • MEMBER
  • 1 POST
  • 2000 MERCURY SABLE
Heater problem
2000 Mercury Sable 6 cyl Automatic 156000 miles

My car has no heat - it is just cold air. I have replaced the thermostat twice and flushed everything out and still nothing. Someone said it could be the water pump but I don't want to stick a couple of hundred dollars into it and it not fix the problem. First of all, does anyone have any suggestions and second of all, is there a way a local mechanic can tell for sure what the problem is? Thanks.
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check and test the water pump if okay if it has a heater control valve check that-also for a clogged heater core

One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad. The other cause might be a bad thermostat that is not opening properly (remove and inspect the thermostat), or a clogged radiator.
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
CLINE07
  • MEMBER
  • 2 POSTS
  • 2000 MERCURY SABLE
Heater problem
2000 Mercury Sable Front Wheel Drive Automatic 90000+ miles

My heater will get warm for a minute or two, then it gets cold. I have changed the thermostat and checked the hoses for blockage. How do I check the door to the warm/cold controller?
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
If you open the hood and check by the firewall you will notice two heater hoses going into the firewall and connect to the heater core
this is a common problem that I've seen and is the heater core need to be flushed
for start
Check coolant level
Is the car reaching operating temp
Check heater core hoses if both are hot,
if both hoses hot and not enough heat inside suspect blend door actuator
if not 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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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
CLINE07
  • MEMBER
  • 2 POSTS
I flushed the heater core but didn't pinch the bypass hose. Not sure where this is? The heater is working better, it blows warm air as long as the rpms are 2 or higher but blows cold air at 1 rpm and lower. Could this still be the heater core? Thank you for the quick response.
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Try and flush it again
and it should get better
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Thursday, November 14th, 2019 AT 10:17 AM (Merged)

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