Ford45

1997 Merc Sable 3.0 the heater gradually looses heat and blows cooler air. When I turn it off and let it sit for a about 10 minutes it repeats the process. Do I have plugged line? If so how can I fix this? Thanks,

Bert

You may have an air pocket. Check the coolant leval.

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Bert

KStromberg

How long has it been since you have had your cooling system flushed?

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-1992 Ford F-150 (winter truck)
-1998 Lincoln Mark VIII LSC (fun car)13.591@101.72mph

Sterling_Six

Hello and good day:

You may also wish to check you Thermostat...these do go bad.

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Good Luck and good repairing Sterling_6
"You know, just like in that Book, When Jesus beats up Moses to get Religion!!"

maladora

i am also having this same exact problem in my 97 taurus, after the car warms up to normal operating temp ( usually about half on the temp gauge) i turn the heater on with the fan dial set to the lowest speed and the other dial set to floor/vent mix. with the fan dial on 1 i can place my hand infront of the vent and i feel warm air, if i leave it on fan speed 1 the temp will stay warm for a few minutes.

however, if i turn the fan speed all the way up the warm air goes away within a minutes or so and turns to cold air ( not as cold as when i have the ac on but still colder then i want during the winter )

from my research on these forums heres what ive come up with

1. is the car overheating?
a.yes, look on your waterpump there is a little seep hole, if waterpump is bad there will be water coming out of that little hole.
b. if you have checked your water pump already you may want to replace your thermostat ( its like a 5$ fix )

2. ok so car isnt overheating lets move on to the heater core
a.with the car at normal operating temperature feel both of the heater core hoses they will be next to the fire wall towards the middle of the car if there both hot then you have other problems
b. if 1 is hot and the other is obviously cold then you know you have a blockage in the heater core and you need to flush.

c. heres where im stuck both mine are hot well one is hot and the other is less hot.

so im going to try and do a radiator core flush then move onto the next thing.

3. assuming all these things arent the problem
a.replacement of the door actuator
from what ive heard these things can sometimes break and only allow a small amount of air in at a time.

how can you tell if its the door actuator that is the problem? well if youve already gone through all the above steps the only step left is the heater control module or w/e its called.

R.S.LOGAN

" heres where im stuck both mine are hot well one is hot and the other is less hot ", that is normal on a heater system . Make sure after flushing , you bleed cooling system and eliminate any possible airlocks .If you can get access to heater flap , try moving by hand and see if that solves problem.

Bert

It's probably the blenddoor not moving. With the key on and engine off if you turn the control from cold to hot you should be able to hear it run to the opposite setting. It's not very loud. If you don't hear it, the blend door motor is the problem.

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Bert

Taurusbob

I've looked under the hood and found out that the ac engages in EVERY POSITION of the fan position swith exept for Vent and Off. I can't believe this. Has no one noticed this stupid wiring set-up. EVER? in the last 15 years that it has been that way. Please tell me I'm wrong.

Charleydog01

I have had the thermostat and the heater core replaced. Now, about two years later, no HEAT. I get heat if I place the setting on A/C MAX but none on heater or defrost. Will not pay another $600 for another heater core. The garage is just stabbling blindly now by saying that it may be this, it may be that. I'll live with the heat from the A/C MAX since this is a 1998 car. I have always maintained this car and have no other problems.

chipset

Your wrong. That is the way it's supposed to work. Normal. It's done for faster preheat in cold weather. The compressor will always run in defrost. It's called
defrost over ride. In the rest of the modes the compressor will stop running after a short time.