jaybird531

I purchased a 2000 f150 with a 4.2 engine. I notice that now that it is getting chilly outside, I cannot get any heat in the cab, just cold air. I have replaced the thermostat, and that did not work. I noticed that the top radiator hose was hot, and the bottom was cold. I replaced the radiator thinking that it was clogged, and still have the same issue. Seems like low flow and no heat...The temp guage stays in the middle, so, I am baffled at this point. Seems like the obvious logical steps amounted to nothing but money for new parts. Any help will be greatly appreciated.

FX4_GUY

I know on my 1993 F 150 there is a valve by the firewall on the passenger side I want to say it is vac driven .. I have moved it manualy and sprayed it with WD40 before and when it moves in and out the the heat would work.. It also could be a clogged heater core..

Ryano

I have a 99 the same problem, sounds like the blend door is not moving to the heat position, there can be a few reasons for this! check the fuse's,bad ele motor that turns the door, broken door. Broken door is a good bet.

Read some the search results for heater problems.
Heater treater has good info also, I'm doing there procedure now but trying to use my old door.

If it is the a broken door you can get emergency heat by removing the door then temporaly blocking the area that allowed air to move into the cab throught its AC path. I just shoved a few t-shirts in the hole util I get the door repared or replaced. This forces the air follow the heat path, you will not have control of how much heat, other that fan speed and rolling down the window.

Let us know how it works out.
Ryano

jaybird531

I appreciate the comments. There is no heater control valve on the firewall, so the door makes sense. But the lack of coolant flow and no pressure buildup with no overheating is still throwing me.

Ryano

Dont know what to say about the preasure build up!

If you bring the truck up to operating temp and turn heat on, both HEATER hose's going in at the firewall should be the same temp aprox.

If the hose's are the same temp this means hot liquid is circulating through the heater core.

What does your temp guage read on the dash?

Here is a picture of under the center of the dash , the white box on the right with a ele plug is the stepper moter witch turns the door . To remove it follow the directions over at heater treater video #1, easy and doesnt take long.

jaybird531

The guage shows in the middle. The heater hoses are cold, and the bottom radiator hose is cold. Like I said, I am stumped...All the comments I am getting are at least getting to narrow down the list, and I really do appreciate them..The engine is not overheating, thought there seems to be no flow...I drive 65 miles to work, with no problem except for heat (or lack thereof) and cold hoses...no overheating.

Ryano

Is the t-stat installed the right direction?

When you installed the new t-stat did the anti-freeze look clean?

How many miles on the truck?

I dont like guessing at this but maybe your water pump might have something going on with it! At least one of those heater hoses should be hot after 60 miles, even if the heater core was cloged.

ARE YOU SURE THE RAD IS FULL?

woodenhead

how do you get to heater treater video?

Chris760

Hey Jaybird...FINALLY...someone with the same problem as me! Let's tag team this problem...I have a 1998 F150 XLT with 102,000 miles that I bought 4 months ago.

Here are the problems:

#1 My heater does not get hot
#2 Both my heater hoses are cold
#3 Top Radiator hose is HOT
#4 Bottom Raditor hose is COLD
#5 I hear the flap move and air change when heater is pressed in cab (no problem there)
#6 NO overheating issues and Temp reads right in the middle on gauge

If it were the heater core at least the hose going to it would be hot but both are cold
Why is both heater hoses cold AND bottom radiator hose cold? I'm new to this...is it a flow problem, thermastat, water pump? I want my heater back on and all hoses cold is worrying me that my engine is gonna blow up despite the perfect temp dash reading.

One more thing...When I bought the truck last year used, the heater never worked. There was also sooooo much brown crap in the radiator resevior so I had it flushed at Jiffy Lube. It still doesnt look very clean and chunks of brown crap in there. I plan to get it flushed again, but I still shouldnt have these problems.

jaybird531

I am completely baffled...I have replaced the thermostat, and radiator..thinking both were bad...cold lower hose...clogged radiator...I have never seen a water pump do this, but I am gonna try it...someone says that a minor leak in the head gasket could do it, but again, I have never seen a head gasket do this either...If the water pump doesn't work, I am going to have to do the head gasket...I am just guessing now, as I have eliminated all obvious (that I can think of) options.