Poor Heat in Both Front & Rear Units

I have a 2002 Expedition 5.4L 99K mi runs great. Coolant levels are fine, no leaks, never had to add anything to it. Temp gauge comes up like normal within 3-5 min it moves, then goes to 1/4, then when warmed up and stays where it has been for the many years I've owned the vehicle (since new) right about half way (maybe a smidge more) after about 15-20 min.

Heat on a day in this cold winter just doesn't cut it anymore. One day its luke warm and other days (only when outside temp is above 40) works just OK that I can take my jacket off on long drives and be comfortable but I leave the heat on 90 all the time. I use to be able to remote start the car once or twice and melt 4 inches of snow off the car, the windows, completly de-ice and dry the windshield and almost melt away the snow on the top of the car. I was sweating! Now this problem started a few weeks ago all of a sudden....

I read things on the blend door being stuck or broken leg, but when I change the temp from 90 to 60 using the manual temp control I can definitely feel the difference of the cold air coming in and then back to warm when I go back to 90. I can feel it as I gradually change the temp or do it more rapidly. Lines are all hot (can touch and hold them just fine) but hoses don't have any pressure to them to me. I squeeze the upper radiator hose easily and it makes the level in the degas tank move a little with NO BUBBLES. I squeeze the heater lines and they feel hotter than the radiator hose but almost like nothing is in them, no pressure. Not sure if they did before or not because I never had this problem before.

Today it is 38 degrees and I have a temp gauge saying I have exactly 90 degrees coming out the defrost vents but to the touch it doesn't feel it and its not enough to melt any snow or ice off the windshield even after running the car for almost an hour. Today there is no ice so can't test it really but the colder it is outside the less heat is is inside. Its barely warm when it is 5 degrees but its not ice cold air coming out of the vents, its just barely warm and barely enough to take the fog away on defrost.

I've read about bad water pumps and air in the coolant system but with metal propellers and no overheating and factory idiot gauge within the norm I doubt it. Same thing with a suspected thermostat I think I would be seeing something even though its just a factory needle gauge if it was stuck closed. I don't think it is stuck open because it would take almost forever to move the needle gauge to normal range and probably would be less than normal.

Any ideas on things I can do to check? There is no heater control valve, just a blend door from what I see and read on the web. So what tells the coolant to flow through the heater box and into the heater core? Fans are blowing, air is moving, its just not very warm. I can even stick my fingers in the degas tank as the coolant after just now running for an hour and a half is only 91 degrees. Is this just the engine temp warming it up being just an overflow tank or is it suppose to be as hot as the radiator and flow in and out and I'm suppose to see it turning up every time the thermostat opens up?

Heater lines feel hot like there suppose to but don't feel full and kind of soft. Ran the car with degas tank open for all this time (1 1/2 hours) and put a piece of tape on the level line (2 inches above cold mark and an inch from over flowing) and it has never moved unless I squeeze the hose. But when engine is cold it drops to just above cold mark and goes back up 2 inches when warm. Had the heat at 90 the entire time and I got in and it was just comfortable but not a sweat box as expected and should have been.

Any ideas?

Thanks in advance

If you have access to an ir temp gun I would check the temps of upper and lower rad hoses plus the heater hoses once the engine is up to temp.

The ir temp gun is the pistol grip temp guns with the red dot laser pointer.

check along the full length of the heater hoses you should feel about the same temps on both hoses. also the temps should be above a point where you can not hold them If you notice a difference in the temps anywhere the hoses you may have a blockage.

From the sounds of it I would suspect that the T/stat may be stuck open or that the water pump isn't pumping as it should be.

With you saying that the temp in the overflow tank is only 91 deg tends to make me think the above is your problem and if you can hold you hands on the heater hoses after running for over an hour would also tell me your not getting to temp

What would be nice would be if you had a obd2 scanner that would tell operating conditions

I have an actron cp9580 OBD tool, use it for codes and bought one last time I had a coil go out to tell me which one. Not sure if it will do temps or anything.

The hoses are more hot than warm, but with temps in the 20's and 30's I have no problem keeping my hand on the hoses. The heater core lines feel hotter to me. Maybe cuz they are smaller diameter and hold heat in better or dissipate it more easier....

I felt the hoses from the water pump to the fire wall and they were steady temp all the way through. It was a little hotter than what was coming out of the ducts but not like night and day.

Does anyone know if the Actron scanner I have will read what your asking?

Is the overflow tank suppose to circulate what is in the cooling lines or is it just an expansion tank or over flow when needed and closed otherwise from the flow.

If the scanner does read temp, it will only show what the coolant temp sensor is reading. Not what is going in and out of the heater core and radiator.

were you able to hold you hand on the hoses for any length of time and if so how long

I have the 9580A and can read coolant temp. Lately I have been using a obd2 blue tooth reader and the Torque Pro app paired to a tablet or smart phone I find it easier to set up and get different readings

Yes, I can hold the hoses just fine. They were warm, just not burning hot.

Its seems hotter at the heater hoses going into the core, not burning or anything but much warmer than the radiator hose. If the thermostat was stuck open, why would the temp gauge come up in shifts like normal though? It would take forever to warm up wouldn't it? I see the temp gauge at regular mark but that heat just isn't coming inside and off the heater core.

I bought a 192 thermostat yesterday but they didn't have the right O-Ring, going to local store in town today and gunna swap it out in a little bit just for kicks. Shouldn't take too long at all. It is the original TS as well the water pump from 2001-2002 when the car was made so who knows.

I was thinking though, does the cooling system flow open into the degas tank on each cycle? Or is it just a "just in case" where the pressure builds up or something in the hot summer months? Should I see circulation in the tank each cycle? And If the TS was open wouldn't I see it all the time?

Thanks

RDEXPO02 said:

If the thermostat was stuck open, why would the temp gauge come up in shifts like normal though? It would take forever to warm up wouldn't it? I see the temp gauge at regular mark but that heat just isn't coming inside and off the heater core.

Thanks

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It might not behave that differently since you aren't getting very cold weather. It could only be taking an extra minute or two to warm up which you might not even notice.

Thermostats are designed to fail fully open. I've never heard of one failing closed, so that's where I would start. Its a guess, but its a cheap and easy place to start.

If you can hold the hoses I would say your temps are lower than 120 degrees. The overflow tank is in the water circuit but you will not see circulation in the tank as it only has One hose which allows for coolant to either enter into the system or allows for the expansion of the hot water to enter into the overflow tank. If possible could you take a picture of your temp gauge before you put a new T/stat in.