cold air blowing from heater vents

If its not a defective thermostat-could be one of the following -air mix/blend/mode doors and a vacuum/actuators-HVAC control module

This guide can help

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

Thanks for getting back to me
You mentioned a diagnostic price, does the price range vary depending on the problem or the repair shop? Any idea what the average repair cost might be?

Honestly Sir-it really depends what needs to be repaired and also the labor cost varies with location-the best thing is to shop around-could be just as simple vacuum hose disconnected or a binding door its hard to say-they have to go behind the dash to get at it.

I would like to give a good feedback for a fast, easily understandable reply, but can't figure out your feedback point system?

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Heater problem
1999 Mercury Sable Front Wheel Drive Automatic 170000 miles

I have no heat in my car, i have a new water pump, thermostat, heater coil, head qasket changed and still no heat, is there a switch or panel, shutter that needs to be open, and is there something i can do myself

Here are a few suggestions:

-make sure your level of coolant is good, and the system bled for air.
-The blend door actuator may be out.
-The blend door may be broken.

when you turn the switch from cold to heat, do you hear the blend door moving inside the panel?

Here, check this website, it'll give you an idea of what could be your problem:

heatertreater.net/Mercury%20Sable%2096-07.htm

Great suggestions
Also we find it
Very common for the heater core to be clogged and need to be flushed
Isolate and flush heater core
Need to know how let me know

It is quite likely that the heater core is clogged. It generally gets full of debris that doesn't settle in the radiator.

Drain the system, and have a qualified repair technician remove the heater core. It is located inside the car under the dash, and can be cumbersome to remove. Make sure they put plenty of towels down to absorb radiator fluid as this stuff reeks and is difficult to remove from carpet.

Flushing out the heater core manually, assures free flow of water, reinstall then check for leaks. Refill with the proper 60/40 mix of antifreeze to "distilled" water, and leave the radiator cap or expansion tank cover off, while you run the engine to purge the system of air. Once the engine reaches an optimal temperature of 180 degrees, close the cover, and check for heat.

If the car doesn't have heat at this time, then either you were sold a defective thermostat or the heater door isn't opening up properly. In which case the vaccuum lines may be broken.

Heater problem
1999 Mercury Sable 6 cyl Front Wheel Drive Automatic 65.000 miles

i just changed the thermostat and coolant and my heater gets warm but not hot, it is full of coolant. what do i do next?

Hi:
It sounds like the heater core may be plugged. feel both heater core hoses to see if they are both hot with the engine running and the heater on.

Let me know what you find.

Joe

thanks, i will try that.

i am a single mom of 3 and have to fix this myself so please explain if it is thermostat where would it be and how to fix or what else could be the problem heat worked just fine last year

changed thermostats 3 times blew out heater core knob just goes round and round but have great air cond.

If the knob going round and round
have to start by checking the knob and switch 1st
check heater hoses if both hot
problem is on the inside

good luck

my 1999 sable is not putting out very much heat. At +25 degree's it can barely defrost the windshield, i put a new 195 degree thermostat in yesterday and that didn't help. I flushed the cooling system out a couple of times and even reverse flushed the heater core a couple of times. Do you think the heater core might need to be changed. Jim D

Sounds like the heater blend door actuator dorman part number 604-206. Otherwise something is blocking the door itself. Let me know what you find.

This is a response: The car(1999 Mercury Sable) engine gauge has not changed in speed to warm up or how warm it indicates. Cabin is receiving very little heat.

Check the thermostat and the heater core if its clogged-start here

thanks so much...appreciate your help.

My 99 mercury sable blow's out very little heat. I have flushed out the heater core,replaced thermostat but still not hot air.I don't see a heater control valve in-line on hose.Any ideas?

Hi there,

Check this link; it could explain your problem:

https://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals

Hope this help

The control is turned on heat, but very little heat is felt thru vents.

double check your coolant level. if it is a little low this will drastically effect your heat. feedback and votes are appreciated.

My heater is blowing cold air only. What could be wrong with it. I have had it in the shop they changed the thermostat. Said it woul;d work but it doesnt. Really need some advice before the temps drop.

Hi there,

The heater tap or the controller may have failed, to do a basic check, with the heater on& the engine at normal operating temp, both heater hoses going into the cabin should be hot to touch, if not there is no circulation through the heater and this will be the reason there is no heat in the cabin, check this out next.

Mark (mhpautos)