99 Taurus Heating problem

My 99 Taurus doesn't seem to put out hot heat. I have changed the thermostat, and the temperature switch (hot to cool). Still after engine is warmed up, the best I can get is cool to warm air. Is there a relay, or do I have a possible problem with the heater core? It's getting to be winter in Michigan, so I need to resolve this one quickly!!

Your heater core probably is filled with gunk. You have to flush the heater core from both sides using a garden hose to remove the particles. There are many posts about this procedure further back in the threads. Some people have posted drawings which should help.

OK - I am stumped. I took the hoses off the heater core, and blew it out. I was able to blow hot water through and flowed well, both directions. Also blew through the hose from the water pump to the heater core, again no problem. Took apart the water pump - no builup or gunk, and all the fins are in place and fine, and the wheel turns with no resistance. With the drain plug still out of radiator, I blew into the hole downstream of water pump, and air blows freely out the drain plug. Oh yeah, after blowing out the heater core, I did reconnect everything and ran the engine, still no hot air. The bottom hose to heater core is hot, top one cool. Help!!!!

You might have to replace your blender door. This device turns on the heat by letting hot water to access the heater core. If you ran water both ways through the heater core and it came out clean, it's possible that the door doesn't open which allows the hot water to go into the heater core. After cleaning my core, I have heat!

Good luck. Search the forums.

I'm have the exact same problem. (except I live in Mississippi and my wife wouldn't have grounds for killing me if it doesn't get fixed)

Ours is a 99 Sable and I’ve felt the hoses and the hose from the water pump "Ts" with one section going to the heater core and the other section going to another T which is evidently the return from the heater core to the engine block.

The first T mentioned is a plastic formed piece that is permanently attached to the hoses – hose coming from the water heater is hot – hose bypassing the heater core is hot – hose going to the heater core is warm, but not hot to the touch.

Is there a mechanical valve inside this T or is the blockage inside the heater core?

I guess I could just cut the T out to see, but I’d rather be prepared to put it back right at the time.

Any help would be appreciated.

My 99 Taurus doesn't seem to put out hot heat. I have changed the thermostat, and the temperature switch (hot to cool). Still after engine is warmed up, the best I can get is cool to warm air. Is there a relay, or do I have a possible problem with the heater core? It's getting to be winter in Michigan, so I need to resolve this one quickly!!


you might have air in the system. keep it topped off with coolant, and buy a $5 radiator cap. mine improved a good bit with a new cap!

Update for all... after all the work of taking off the water pump, changing thermostat, and checking all hoses and connections, I finally bowed to misery and decided to buy a new heater core. We filled the new core with water and tranferred it to a pitcher, then took a hose and attempted to fill the existing (still in car) core - it took about a tenth of the water. I followed the instructions in the Haynes manual, and took apart the entire dashboard, all the way to the firewall. The funny thing is that when I actually got to the heater core housing, three little screws were all that held it in, and ten seconds later, new heater core (after five hours of taking everything else off). Needless to say it is a BIG job, but finally have heat and at 5 degrees out...it feels good!!

The bypass hose reduces pressure to the heater core. This allows sediment to build in the core. This is a common problem. If you pinch shut the bypass hose completely you can sometimes use an air compresser to blow out the core. A few thousand miles later the problem will still return. Not good sound engineering design by Ford.

I replaced my steel heater lines runnning up the firewall with Gates rubber heater hose and Gates connectors and elbows to replicate the steel lines running into and out of the heater core. That seemed to be the real problem for me, I did flush the heater core at the same time I replaced the lines. I still have great heat and it was well below Zero here today!!!! I have a 1999 Taurus and the Ford dealer flushed my system including the core twice last year and it did help some but didn't get the heat as warm as I thought it should be. Late this fall I decided to flush the heater core myself and the steel lines were rusted so I flushed the core and replaced the steel lines with rubber and WOW what a difference, the heat has been great. My heat now measures 170% coming for the front window defroster. My Ford dealer could only get the temp up to 140% from the defroster....
Hope this helps, let me know if you try it and it works for you...Ed
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The bypass hose reduces pressure to the heater core. This allows sediment to build in the core. This is a common problem. If you pinch shut the bypass hose completely you can sometimes use an air compresser to blow out the core. A few thousand miles later the problem will still return. Not good sound engineering design by Ford.

Intersting thread.

I suffer from the little-to-no-heat problem in my 98 Taurus wagon. I wonder what the effect of removing the heater core bypass would be? Has anyone tried this?

Three months ago my the coolant was rusty brown, so I had the mechanic flush it. Didn't help the heat. This past weekend I noticed the coolant is on its way to brown again. I flushed the heater core. I didn't get a lot of gunk out and was rewarded with only a marginal increase in heat at idle speed (previously there was no heat at idle).

I think maybe the water pump is shot. I'll try replacing it the next time I have some spare time. I noticed while flushing the system with detergent that the coolant seems to be moving pretty slowly through the system. I'm not sure how fast it's supposed to flow but it seemed to have weak pressure to me.

Does anyone know how hard a job this is? It looks like there's more room to work with than there is on my 93 Saturn. Maybe I can jack up the engine if it's hard to get to.I just flushed my heater core over the weekend and saw only a marginal improvement in heat. A few months ago the coolant was rusty brown so I think the water pump may be shot. Even though it's been