No Heat all of the sudden?

[AbbottK28]

1997 xlt 5.0 awd. Im in Michigan and the weather has been fun to say the least these past few days, but the truck has been great. This morning when i warmed it up to go to work it started kinda rough and slow, it was -11 out at 6am. Anyways, driving i noticed no heat from the vents.
Heres what stumps me, I replaced the rad, and thermostat late summer, and I dont have water(that I know of) in my coolant. The truck ran just fine otherwise, temp gauge right where it should be, no overheating, fan on the blower working fine, but no heat!
Any ideas on where to look next would be much appreciated! Also, I ran through my fuse panel, and though a few are missing (always have) I doubt that would have anything to do with it considering I had heat yesterday anyways. Fuses were all good otherwise. Any help? Please?

 

[all4ford]

I am just up the road from you a bit. This cold is hard on vehicles.

Two things come to mind on your heat issue. Did you flush the cooling system? You could have a plugged heater core. Check your heater control valve too. It's on the passenger side. It controls the temperature selection (hot/cold). Make sure it's moving freely. If I'm not mistaken, it's controlled by a small vacuum line that controls that control valve.

 

[1992fordgreen]

It's most likely the blend door actuator that failed. If not that, the fitting plenum that the actuator turns in has crumbled, as old plastic does.

http://www.explorerforum.com/forums/showthread.php?t=214332

 

[koda2000]

you say you don't have water in your coolant (that you know of). what does that mean? you should have a 50/50 mix of antifreeze and water. where is the needle on your temp gauge once the engine is fully warmed up? even in cold weather it should be near the center. if it's down near "C" then your thermostat is not working properly (even if it is fairly new).

 

[rb142]

I was thinking blend door too. Check the heater hoses under the hood running to the heater core to see if they are warm. That pretty well narrows it down to the heater core and the blend door. Check for a broken vacuum line.

Be careful out there in the cold. I'm not far from you either, and I know what you mean. It was -13 (-39 wind chill) when I left for work at 6:30 this morning.

 

[AbbottK28]

thanks for the replies. What i meant by not water in the coolant was it wasnt just water i guess, wasnt really thinking before I spoke. The temp gauge at "normal operation" is just under halfway up on the gauge. I will take a look today after work at the plenum and see what I can find. Also yes I did do a system flush before I replaced the radiator and also again after. Not sure if it was necessary to do it twice but I had the time so I figured might as well.

 

[JimMadsen]

You may want to do a heater core flush. Did one last year about this time. What I did was disconnect both heater core hoses and put in a bypass so I was not spilling coolant. I plugged a couple foot clear hose on one of the hose ports for the core and sprayed hot water from a hose into the other. The hot water keeps the hose pliable and your fingers from falling off in this cold. Drain into a bucket and see what comes out. When coming out clear, switch to the other port. Then switch again. Keep going back and forth until you get bored or no debris coming out. Hook everything back up and see if you have heat. Keep an eye on the levels as you now have some air in there to work out.

Just did this to my sisters pathfinder. Didn't work, probably because I found transmission fluid in her coolant.... yeah that wasn't good.