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Heater air only luke warm (?)


AeroRamer

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I did not want to threadjack the 'Engine underheating?' thread, so I am posting a new one.

I just noticed the same problem listed on the other thread with my ’00 Limited. The heater is just blowing luke warm air. The heater used to blow really hot air to the point that placing my hand near the vents would feel uncomfortably hot.

The engine temp gauge is about normal. The radiator and a cracked thermostat housing were replaced earlier this past summer. I have no coolant leak from the radiator, thermostat housing, or heater core that I can tell.

Yesterday, after a drive from work I checked the coolant level in the overflow tank. It was normal. When I opened the radiator cap I was expecting coolant to rush out but all I got was a small and brief ‘Pfffftttt’ and no coolant rushing. I poured some 50/50 coolant in thinking the radiator was low on coolant but it only took about 2 cups.

Next, I am going to check the temperature sender wire connection, try to burp out any trapped air, and flush the heater core with water and/or air, in that order. Any other ideas?
 


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AeroRamer

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BTW, I am also going to check with the shop that replaced the radiator and thermostat housing to see if they can troubleshoot the problem under warranty since they were the last ones working on the system. But I am sure that most likely they will tell me that it has been to long or find something else wrong with it that was not part of their earlier fix and that will cost me more money. :(
 




BrooklynBay

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DjDom

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It has to be the thermostat.
My truck had the exact same problem last winter. It took forever for the engine to warm up and the heat was blowing barely warm air.
Changed the thermostat, better gas mileage and burning hot heat! :D
 




Turdle

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Don't forget the blend door:(

Is the coolant bypass valve opening to allow coolant to the heater core? Feel both heater core hoses next to the firewall. Once the engine is warm, both should be pretty hot to the touch.


If they installed a "failsafe" type thermostat, it may have prematurely popped open.
 








AeroRamer

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I am taking the truck to the shop this afternoon. They replaced the thermostat housing back in April of this year, and the radiator and hose in June. I am not sure if they replaced the thermostat.

On the auto parts website I noticed that there are two thermostats listed for the 2000 Explorer. One is listed as a 195 degrees thermostat with a 190 degree opening temperature for the SOHC engine. The other one is listed as a 180 degrees with a 180 degree opening temperature for the O.H.V engine.

From the video I took, the coolant temperature goes up to a max of 194 degrees and then drops to about 182-187 degrees. Can I deduct from the video that the thermostat is most likely the 190-195 degree thermostat? If that is the case it should be the correct thermostat for my SOHC Ex.
 




DjDom

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Seems weird to me that you need to keep adding coolant. It's as if they didn't burp the system properly and fill it up completely..
 




AeroRamer

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Update:

Here is where I am at. I ran the OBD2 on my other car using the troubleshooting instructions found here: http://troubleshootmyvehicle.com/ford/4.0L/how-to-test-the-thermostat-2 to check the thermostat. It worked as listed in the other car. It got up to 223, fan urned on, and the heather hoses were really hot.

When I tested the Ex the main radiator hose was cold before 190, then it got hot as the temperature got up a few more degrees. The heater hoses were hot but not as hot as the other car. Then, the coolant tem settled to about 186-189 and did not raise.

This morning I took the car to the shop. They said the hot air temp inside the cabin is low at about 103 degrees. They think the problem is either a problem with the back side on the water pump or a possible plugged Radiator as there appears to be no circulation on the radiator. I get the impression that they installed the radiator and forgot to unplug something or remove a plug somewhere. Now they want 2.5 hours of diagnostic for the pump at $99 an hour to ‘check’ the pump. And if it is not that…they will go from there.

I am thinking they should remove the radiator and check it for proper installation before anything else since they replaced it last and it is under warranty. But that means no money for them unless they troubleshoot the pump.
 




Turdle

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The heater core needs to be checked first, as going from your description I think the heater core is clogged. It might benefit from a back flush.
 




Johnsanders

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It has to be the thermostat.
My truck had the exact same problem last winter. It took forever for the engine to warm up and the heat was blowing barely warm air.
Changed the thermostat, better gas mileage and burning hot heat! :D
whoever posted a piece about replacing the thermostat because the heater was blowing only lukewarm air I appreciate that and my gas mileage kind of sucks too so those are my problems right there my temperature gauge does not work though and the heater only blows lukewarm so I appreciate that information
 








ImpactF0nt

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Try a coolant change/flush and flush your heater core.
 




aryork

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... I just noticed the same problem listed on the other thread with my ’00 Limited. The heater is just blowing luke warm air.

Same '00 Limited, 130k-ish miles. But, air not luke warm - just cold (seems same as outside). No fluid leaks. Blowing fine on the floor. I will keep searching, but if anyone can point me to a good thread/video on changing the thermostat, I would appreciate it. I have not monitored engine temp, so need to do a bit more troubleshooting (it's my kids car, not mine so I do not drive it much).
 




Mbrooks420

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Same '00 Limited, 130k-ish miles. But, air not luke warm - just cold (seems same as outside). No fluid leaks. Blowing fine on the floor. I will keep searching, but if anyone can point me to a good thread/video on changing the thermostat, I would appreciate it. I have not monitored engine temp, so need to do a bit more troubleshooting (it's my kids car, not mine so I do not drive it much).
If you have no heat, and the coolant level is good, you likely have a blend door failure.
 




koda2000

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I'm leaning toward a broken blend door. If you have coolant in the reservoir but have to add coolant to the radiator you have a leak somewhere. You should never have to add coolant to the radiator if there's coolant in the reservoir. Having to add 2 cups (16 ounces) is not enough to effect the heater though.
 




1998Exp

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Video

Hoses are warm. I can certainly hold the hoses indefinitely with just a little discomfort.

Here is a video I took a few minutes ago with the OBD monitor running.


Make sure the coolant valve (on the heater inlet tube, next to the firewall) is fully open. It's operated by vacuum, but you can disconnect the vacuum supply (make sure to plug the end of the tube) and force it open by hand.
 




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