no heat in truck...Help!

[Camaro86SHOCKER]

so recently the heat just kinda withered to nothing in my 97 f-150 4.6 v8. It worked perfectly last year. I figured it was the coolant system so we flushed everything out numerous times, replaced upper and lower hoses and the thermostat and replaced all the fluids and used peak antifreeze. Got all the air bubbles out and it started to get kinda warm. Well thats it. It gets kinda warm which is exactly what it was foing even before we flushed everything and replaced it. The truck has 0 leaks anywhere and i'm just not sure what to do but this is flat out miserable. Anybody have any ideas or something similar happen to them?
Any helps appreciated, considering im in this thing at least 3 hours every single day, and its awful.
thanks
-Justin

[transman]

did u try to flush the heater core

[8banger]

Feel the inlet hose to the heater core..Hot ? warm? then check the outlet coming form the heater core...Warm cool...Clogged core..Both hoses hot..another problem..

[PaulFiveOh]

Feel the inlet hose to the heater core..Hot ? warm? then check the outlet coming form the heater core...Warm cool...Clogged core..Both hoses hot..another problem..

+1 - Cooling is the easiest system on the car to troubleshoot.

[graysonracin]

Feel the inlet hose to the heater core..Hot ? warm? then check the outlet coming form the heater core...Warm cool...Clogged core..Both hoses hot..another problem..

+1 on the heater core, try flushing it by itself. Another thing is check to see if the heater controls are operating the blend doors, you should be able to hear it make alittle noise switching from hot to cold.

[PonymanfiveO]

I've herd those things are a nightmare to put a heater core in. I've never done one though. Ill look it up on alldata and see how bad it looks.

[8banger]

Big job if he indeed needs one.Book time is 7.0 plus evac and recharge...Dash puller...and then Evap/heater core box assembly...

[Black Horse]

There is a short cut.....but I wouldnt recommend it for a first timer.....pull the dash and do it right

[BigBadStang]

There is a short cut.....but I wouldnt recommend it for a first timer.....pull the dash and do it right


Lol...a SawZall Dave? :lol:

[Camaro86SHOCKER]

did u try to flush the heater core


I flushed the system as a whole but how do i flush just the core?

well i was always under the impression that if a heater core isnt cracked or leaking that it doesnt need replaced, true untrue? If its clogged is there a way i can just take loose the hoses and hook the air compressor line to it and maybe blow it out? dont laugh if thats a stupid idea ive never dealt with a possibly clogged heater core ive only replaced them on several occasions for leaking.

Yeah i thought of the blend door but i hear it moving and if i switch to cold it will get colder.

[bobtsgt]

need to take the hoses loose where they attach at the motor and purge water in each one in hopes of moving the clog and /or purging it out of the core. Since the truck is back together do like said above and get the truck up to running temp, turn the heat on and feel both core hoses for heat. Or if you got a temp gun shoot the hoses and shoot the upper radiator hose for a reference. The core could have rust/scale/ or other crap that has sealed shut or close to it. Are you sure you purged out all the bubbles?

[junk89lx]

There is a short cut.....but I wouldnt recommend it for a first timer.....pull the dash and do it right

would love to know the shortcut seeing how my expi is on its second heatercore...

[Black Horse]

Have you done it once already? If you are experienced, some folks are able to "sneak" the heater core out without pulling the dash. I have done it once. It's a real pain in the arse either way.

[Timido]

I would check the temp of the heater hoses first then make sure the blend door motor turns when you change the temp. I have seen everything from broken blend knob, The switch bad, broken blend door, and motor bad.

[facemelter71]

I bet its the blend door.

On that vehicle it should have a drain for the heater core/evap for the A/C system.If the heater core was bad you would have a leak out of the small drain hole.If its plugged then only one hose would get warm.The other would be slightly warm.Pulling a dash on that bad boy is no big deal and can be handled in a regular garage.BUT,like you said.It kinda withered away.So its either blocked,or the blend door quit workin.Some times when a heater core lets go,you can smell it on the inside if you switch it to defrost.Or on defrost it will fog up the inside of the windshield because of hot coolant leaking to the outside of the heater core.
I cant remember how the blend door functions,be it vacuum or electrical motor.Check it out.

[blk93notch]

is the temp knob hard to turn? i think its a cable. maybe its stretched and its not going over to hot all the way over.

[Timido]

The blend door motors failed alot.

[graysonracin]

I wouldnt use compressed air, just use a garden hose if you got thats not frozen up.:lol:

[Camaro86SHOCKER]

how would i check the blend door? is there something i can physically see?

i'll flush out the core as soon as i can get the hood open from the ice lol. so a garden hose will work? i dont need something with more pressure than that?

[PonymanfiveO]

Justin, Prestone makes a flush kit that you can hook your garden hose right up to your heater hose. You should be able to find it at any parts place.

If not, get an old hose and cut the end of it off. clam a hose barb in the end of it and clamp the other end of the barb on the heater hose. ;)

Hope you have some luck with it.

BTW, if you can flip the hot/cold knob and hear the door move inside and feel a difference in temperature Id say the blend door is fine.

[cobrajoe]

The blend door motors failed alot.

Yup! the blend door is kapish in the Danger Ranger but it went out on hot setting... so no a/c unless I put on max and it still is fighting the heater core!

[slvr87cpe]

i am having about the same problem except my heater blower only works on hi and it aint getting real warm in my 01 expedition :eek:

[Timido]

i am having about the same problem except my heater blower only works on hi and it aint getting real warm in my 01 expedition :eek:

Blower Motor Resister is probably bad. When they go out they usually only work on High. You might have anouther problem with it not getting hot enough.

[slvr87cpe]

where is it at :bigthumb

[Timido]

It is near the blower motor. Follow the wiring from the blower motor it will go to a plug that looks it is plugged into the heater case. There are 2 7mm(I believe) screws holding the resister into the case.

[Timido]

it could be the the switch or wiring also but the resister is what I would try unless you have a wiring digram

[slvr87cpe]

am i going to have to pull the dash to get to this :eek:i looked up under it and saw nothing but the box bottom

[Timido]

It been a while on one of those. Look under the hood and behind the glove box.

[Timido]

Make sure the connector is not burned up also

[tdm309]

I had one of these that did the same exact thing. When at idle it was cold. Try raising the RPM of the motor to around 3000 and see if the heat gets better. If so you have a bad water pump. If its got a lot of miles on it or the coolant was really rusty this is more then likely your problem.

[tdm309]

i am having about the same problem except my heater blower only works on hi and it aint getting real warm in my 01 expedition :eek:

Your truck probably has a bad blower motor resistor. As for the heat thats a whole other problem.

[8banger]

I actually use spare heater hoses differnet sizes 5/8,,3/4 etc about 4 ft long each..pull off the heater hose at the heater core..Attach the spares...get some hot water(inside at the garage,wouldnt do out in the "freezin" cold)...fill up one hose with hot water,,use a blow gun and applyalittle air through that hose(be careful not to use to much air)and flush it out the other hose(watch out makes a mess sometimes)....then repeat through the other hose back flushing it..woks ever time...Gm s10 blazers are notorious for this...

[8banger]

I had one of these that did the same exact thing. When at idle it was cold. Try raising the RPM of the motor to around 3000 and see if the heat gets better. If so you have a bad water pump. If its got a lot of miles on it or the coolant was really rusty this is more then likely your problem.


yep have had cooling systems so rusty the fins on the water pump impellor rusted away causing poor circulation...

[transman]

am i going to have to pull the dash to get to this :eek:i looked up under it and saw nothing but the box bottom

u wont have to pull the dash u may have to pull the cover off under the dash but they always stick them close to the blower motor becuse it cools the resistor

[Camaro86SHOCKER]

Justin, Prestone makes a flush kit that you can hook your garden hose right up to your heater hose. You should be able to find it at any parts place.

If not, get an old hose and cut the end of it off. clam a hose barb in the end of it and clamp the other end of the barb on the heater hose. ;)

Hope you have some luck with it.

BTW, if you can flip the hot/cold knob and hear the door move inside and feel a difference in temperature Id say the blend door is fine.

thank you, thats exactly what i was hoping existed, now as soon as my garden hose thaws out i'll try that.

Yeah the blend door definitely opens and closes.

[02mingryGT]

yep have had cooling systems so rusty the fins on the water pump impellor rusted away causing poor circulation...

+2 daughters Taurus did just that a couple of months ago. Flushed it out and when that didn't solve it, pulled the pump off. No vanes.

[Timido]

+2 daughters Taurus did just that a couple of months ago. Flushed it out and when that didn't solve it, pulled the pump off. No vanes.

3.0 taurus were real bad for rusty coolant. Ford had a fix that was a coolant bypass and flush the crap out of the block.

[slvr87cpe]

my problem was the resister was all rusted away replaced and everything is good now thanks guys :bigthumb

[Camaro86SHOCKER]

is there a way to tell if its the water pump or the heater core? either way i'm not looking forward to this. The engine runs perefectly cool though so i dont see how it could be the water pump. As of this morning i have no heat at all now. its miserable.

[1badasp]

that suck, dude. I feel for ya