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Mercury Sable Heating Problem

11-13-2003, 10:42 AM
I have a 1998 Mercury Sable sedan. The heat does not work -- it blows cold air.

Sometimes if I turn it off for awhile and turn it back on, it will blow warm air for a few seconds, and then blow more cold air.

I know there was a leak in the coolant overflow talk. I replaced the tank myself and then had Jiffy Lube run a full radiator flush and fill. The tank is filled to the upper bound of where it should be.

There are some comments here already about this same problem... but the radiator flush didn't work for me! Is there anything else this could likely be? Did Jiffy Lube perhaps do a poor job on the flush?

Thanks muchly.

11-13-2003, 03:03 PM
next step is replace thermostat and gasket,it could be seized.good luck. mike

01-29-2004, 05:24 PM
hey I just fixed a 96 sable with the same problems, replaced the thermostat, then flushed the the system from the back. behind the block there are two hoses that go into the fire wall one of those comes up on the pasenger side and is easyer to detach the pressure clamp hook a hose to it, open the refill top and open the drain at the bottom of the radiator. I was shocked at how much rust came out. I let it drain for about an hour, well the heater works now, maybe jiffy loob just flushed it from the coolent resevor(where you add the coolent) and then let it drain out the bottom, that would not fix the problem. good luck I hope this helped

01-29-2004, 09:08 PM
Check thread titled, (Taurus heater fix!!) Flushing the heater core worked great for me!

02-16-2004, 05:39 AM
This must be a common Ford problem, regarding heater cores and no heat! I own a '99 Mercury Sable GS, my sister owns a '99 Ford Taurus SE, and my brother in law owns a '02 Ford Ranger XLT. All 3 vehicles do not have heat at all. My vehicle and my sister's vehicle both needed new coolant reservoirs, both were leaking where the top is glued to the actual reservoir. I have flushed out the cooling system, but I did not remove the heater core hoses. My temperature guage is reading normal at operating temperature, so I do not believe the thermostat is bad, I will try back-flushing the cooling system with the heater core hoses off and post a reply as to how things went!

11-25-2004, 01:34 PM
I just purchased a 1998 Ford Taurus SE Wagon. The car has 194,000 miles. Mostly all highway miles. The car looks and drives great. I had my mechanic look it over and drive it as did I. Neither of us thought to check the heat. I doesn't seem to work. I does warm for a few seconds then blows cold air. I will have the thermostat and the back flush checked. I pray that the heater core does not need replacing. I hear that this item is not a low cost repair. I am grateful to have the car. I simply did not check this issue prior to purchase.

11-29-2004, 09:46 AM
I have a 1998 Ford Taurus with roughly 200k miles on it. It was been a fantastic car with nothing but normal wear and tear maintainence needed. However, the heat has just now stopped working. I had it flushed and was told the the heater core needed to be replaced. Now, I'm not one to readily trust mechanics so I was wanting to see if anyone else had the same problems and the fixes they tried first. Replacing a heater core is not an inexpensive undertaking. Thanks.

11-29-2004, 08:09 PM
warm your car to temp, and feel the upper radiator hose. if its hot, your themostat is ok. pull your hoses at the heater core, and flush it yourself with a garden hose. put on a new radiator cap (only $5 at the local autozone, etc.) and hope for the best. if it gets some heat, but not very good, rev your engine up to 2500 to 3000 and hold it for a bit, if you got heat then, suspect you water pump fins are worn down.

10-28-2005, 01:01 PM
1998 Sable heat hasn't worked. Power flushed and back flushed heater core. Replaced thermostat 2 times. Found a/c running all the time. took out fuse to a/c, backup lights,. Have heat-but not good heat. Also felt lines going into heater core-they are hot-but 2nd mechanic found a bypass line above heater core-heat could be circulating thru there, and not thru core. I will recheck for leaks, as well as show mechanic post on fins (earlier post). Car does heat when revved. But heat gave into cool air again after hours of running car. Again, fuse is taken out of a/c -only way I've gotten heat so far. I have heard that when a heater core goes bad it leaks into the cab.

01-01-2009, 11:54 PM
We found this while trying to figure out why my daughter's '98 Sable's heat wouldn't work. We had the radiator flushed, nothing. We checked the thermostat as suggested by feeling the heater hose, it was hot. What finally worked was pulling the hoses by the heater core and using a garden hose to flush the heater core. What wasn't mentioned is that you have to be very careful to use minimal water pressure so you don't destroy the heater core. Thanks for all the useful information we found here, figured we could pass on what we learned about not using too much water pressure to flush the heater core.

01-02-2009, 10:52 AM
Thanks for passing on that tip, and welcome to the forum!

Just out of curiosity, did you end up popping your heater core by using too much pressure, of did you learn that tip prior to causing damage?


01-02-2009, 07:01 PM
I have a 1996 GL wagon with only 75,000 miles on it and has always been well maintained. It has always been a souther California car so it hasn't had to endure any extream cold temperatures. The car has always had antifreeze and the heat has never given me any problems but several months ago when a heater hose sprung a leak on me I flushed my system and holy moly! I could not believe the amount of rust that came out. After seeing this first hand I would recommend flushing the core to anyone that hasn't done it in a while.


Colt Hero
01-02-2009, 09:42 PM

I've been flushing my heater core near the firewall for several years now with maximum garden hose pressure and no problems. You'd probably have to neglect your cooling system for a decade to blow up a heater core with a garden hose - and even then I'd bet you'd still be OK.

My Taurus GL wagon is 11 years old now with 164k+ miles on it and the heater core, radiator, hoses, and thermostat are all still original from the factory.

01-09-2009, 05:16 PM
The heater cores on these seem to gum up alot my wife has a 96 taurus and ive flushed it twice and have to do it again works great just clogs to easy. I have heard alot of complaints about these heaters but this worked for me twice

Colt Hero
01-09-2009, 07:54 PM
I just replaced my water pump which had disintegrating fins/impellers on it. I can tell there is a difference now with the heat, but it still could be a LOT better. Maybe one more flush will blow out the old water pump debris and I'll be able to get through the winter with sufficient heat.

01-09-2009, 08:49 PM
Until you get rid of those factory metal lines, its always gonna need some attention. New hoses, plastic t's and a good heater core flush and I was good to go. I had flushed the core five times before and never had very good heat. Those metal lines corrode over time and rust and crap builds up it them. You think that you flushed them out, but its only temporary.

01-10-2009, 10:00 AM
We were fortunate enough to figure it out before we had a problem. I took the car to a friend of mine who owns a car repair business. He told us that the heater core was probably plugged and needed to be flushed separately. We were told by the people who flushed the radiator that it included the heater core and engine block, but when our friend flushed the heater core hoses, he said that the hoses and overflow were packed with rust. Once he got that rust out, the heat began working. We were delighted, because my daughter has a 2 and a 5 year old and driving with no heat in Norwest Ohio in the winter is not a good thing!

01-10-2009, 07:43 PM
If you are unable flush the heater core and have to replace it, you need to know that the labor is what makes the heater core replacement expensive. The heater core is actually a very inexpensive part. If you can follow detailed instructions, then you should have no problem with replacing this cheap part.

03-24-2009, 10:09 AM
I thought I posted a reply about the heater core on the '98 Sable, but I must not have completed it correctly. We found out about the flushing the heater core with minimum pressure prior to doing it, so we did not damage the heater core. As for the length of time before it was flushed, you are probably right. The car was given to my daughter by her church, and although they did do basic maintenance on it for her prior to giving it to her, they did not have the equipment to flush it. When the heat went, we looked at the radiator and it was filthy, full of rust and dark brown antifreeze. The same for the heater core. When it was flushed, the rust inside of it was just gross. But, hey, how can you complain about a free car! She is a single mom with 2 kids and was grateful to have a way back and forth to work and day care that did not include taking many busses! Thanks for your responses and concern! :iceslolan

01-02-2011, 04:24 PM
I have a 98 Ranger 3.0-problem is-heater will get hot when first started and let idle, but then gets cold at highway speed, bring to stop and let idle and it heats up again. It has new water pump-new divertor door-new thermostat and cooling system was flushed at Ford Dealer. When idling it will get hot enough to run you out!

01-27-2011, 10:12 PM
Thanks to All. After reading everyones comment I decided to just flushout the heater core without removing it and it solvied my problem of no heat. I was plesenty suprised. I used a preston flush kit for 3.99, it contained a pressure reducer and other connecting pices. I removed both hoses off the heater core and connected the water hose to the outlet side of the heater core. At first all I say was slow moving rusty slug, 3 min later it was clear. Connected up to the heater core inlet side and flushed it again going the other direction. I also decided to flush the rest of the system out since I had the heater core hoses off. I was really dreading replacing the heater core... Thanks again.... 1998 Mercury Sable 191,000 mi.

02-05-2011, 09:46 PM
I Replaced heater core, thermostats, and coolant. Water pump in good working conduction. But my heater was still blowing luke warm and cold air. What I did was pinch the by pass line with Part # 77-4002 Hose pinchers from NAPA

The heater in my car went from 80 degrees to 110 degrees. This is from the vent and not in the cab of the car. Now there is a big difference. Sure hope this helps somebody with the same similar problem I had. Ooooh don’t forget to remove the hose pincher as the weather warms up (Summer time)

I was told that the Mercury/Taurus was over engineered, and that the reason why the heater is the way it is...COLD...

Here is a link on the Hose pincher tool

04-05-2011, 09:11 PM
All, the heater core is NOT that big of a deal to replace and definitely worth the time and effort. There is a sticky note at the beginning of this forum that links to a process where you do not have to remove the whole dashboard. I think it took me 3-4 hours and for the first time, that's pretty reasonable. If I remember right, the biggest pain was getting the hose clamps off the heater core in the engine compartment. I ended up cutting the clamps with a Dremel tool and was able to reuse everything except the clamps. Good Luck..

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