I have read a lot of the threads, but don't read my exact problem. I just bought this explorer in the summer and now I noticed that I don't get real warm heat when it's cold outside. It seems to be kind of luke warm. When I move the lever back towards cold it starts getting cold, but again, I never get really hot air. Could this still be the blend door, or should I look elsewhere?

 

Does your temperature gauge read somewhere in the middle between C and H? Or does it not get much above the C mark? If the latter is the case, your thermostat is probably stuck open.

I haven't experienced the infamous blend door problem myself, but from the many threads on this topic, it seems that you'd either get really hot air, or no heat at all.

 

I had the same problem with my 97 Explorer XLT,i drained the radiator and flushed it out and also disconnected the two hoses that go through the firewall into the heater.I then put a hosepipe in one of the pipes and flushed the heater Matrix out.I reconnected everything and then put some radiatoe flushing chemical in and and drove for 30 miles.When the car had cooled down i drained and refilled the system and now its as good as new.Hope this helps,oh it does explain in the Haynes manual how to do this.

 

As the other posters stated, it sounds like either a stuck Tstat or the heater core needs to be flushed. If the temp gauge is reading normal, then flush the heater core.

 

At the very least, to further diagnose your issue start with the simple and affordable items. Change the t-stat. Can't hurt you and it is good maintenance. Not a bad idea to swap out the antifreeze at the same time as it does loose it's ability not to stop from freezing, but to lubricate the water pump and protect from corrosion of the various metals.

Flushing the heater core can't hurt either, but as a general rule, once they are plugged they are very difficult to get unplugged. I have swapped the hoses around so the flow gets reversed and put in about a half cup of dish powder dish washing detergent. It does a good job as it is heat activated.

If your going to try the detergent don't swap out the antifreeze until after you do the detergent and let it run a few days. Otherwise your just wasting money...

 

If the core is clogged, and you can't unclog it, replace it. It's only about $25 and a simple repair.

 

Thanks for all the responses. I forgot one other piece of info. My temp. gauge fluctuates back and forth, so I am assuming that my temp. sensor is bad. If I replace it and the temp. moves to normal then I will assume that my T-stat is o.k. If so, then I will move to the the heater core. How do I determine if the heater core is clogged? fyi. Also, the radiator was changed this past summer, so the radiator fluid is new.

 

When you say that the gauge fluctuates, does the needle slowly move between C and H? Or does it jerk around quickly? If the latter, make sure that the wire connector to the sensor is on properly. If the fluctuation is gradual, the temp sensor is one possibility, but I would go ahead and flush the system and replace the thermostat first. This would be a good time to replace hoses and the serpentine belt if it's been a while since these were installed.

Get some flushing additive from any auto parts store, and follow the directions before you drain the radiator. Next, splice a flushing tee into the upper heater hose, and connect a garden hose to the tee. Remove the radiator cap (when the engine has cooled!), start the engine and turn on the hose. When clear water comes out of the radiator, stop the engine, shut off the hose, and drain the radiator. I also like to remove the lower radiator hose to drain water out of the engine block, as I never bother removing the drain plugs on the sides of the block. Change the thermostat now, before refilling with coolant.

You can determine if the heater core is blocked by doing what mossy007 did. Disconnect the heater hoses from the engine, and run water from the garden hose into one of the heater hoses. The water should shoot out of the other hose. If the water backs up and you don't get much flowing out of the other hose, the core is plugged up and needs to be replaced.

Good luck!

 

Flucuating temp gauge did it for me. My 91 did exactly the same BOTH times I needed to replace the core.

Heater core is blocked. This is a sure sign. Easy fix and cheap too.

 

I think your Thermostat needs to be replaced. I would replace the thermostat and flush the coolant before I did any expensive repairs. This will only set you back about 20 bucks. My friend had the same problem and we repalced his thermostat and flushed it and now it runs like a champ

 

Is the coling system full? Please check the radiator level when the engine is cold. If is full, check the temp of the heater hoses going to the heater core, both shoule be hot. If one is hot and the other is cooler then thte heater core is pluged. Try flushing the core and recheck. Good lucl.

 

Thanks for all the responses. I am going to check it out this weekend. Don, I didn't quite understand your response. The fluid is full, so I can answer your first question. I didn't understand your other response. If the eng. is cold, then how would the hoses going to the heater core be hot?

 

On my 92 I had a fluctuating guage on fluctuating heat. Turned out the fan clutch was bad. Replaced it and started getting consistant heat. if it turns out the heater core is bad you can replace it relatively quickly and cheaply.

 

Thanks Redboat. How did you determine that your fan clutch was bad? I thought those typically made a noise when they were bad.

 

He meant to say that if the radiator is full of coolant, then replace the cap, start the engine, and then feel the heater hoses when the engine warms up.

However, I'm not sure that I'd agree with that. The heater core is a small radiator, and works the same way to extract heat from the coolant. So if the core is working properly (i.e., not plugged up), AND if the heater is on, then the outlet hose would certainly feel cooler than the inlet hose. But if the core is plugged up, coolant can't circulate through it. In that case, I would expect that the coolant in both hoses would be about the same temperature. Ditto for the case of an unobstructed core with the heater off.