My heater blows cold. When i got the truck it didnt have a thermostat, so i figured that was the problem. i put a 160 thermostat and replaced all the coolant, now the truck will reach operating temp, but still blows cold air. also i dont think the coolant system is building pressure like it suppose to. i let the truck run for thiry minutes and the hoses weren't even warm, nor did they have any kind of pressure on them. any ideas?

 

pressure test the cooling system. it will tell you if you have a sealed system or not.if there is no pressure build up,then you have a leak somewhere. you may also have a plugged up heater core,that would explain no heat blowing .you could have an air lock in the system,a bad heater hose,it may be that your dash control for the heater is not moving the heater control on the heater hoses to regulate the coolant shut off valve on the hose.

 

Does your truck have Air Conditioning?

If so, it has a heater water valve and this little charmer:

A/C/Heater Temperature Control Selector Valve Assy.

If you have A/C, I'll tell you what all this refers to, where the parts are located, and what happens when these parts fail.

Some vehicles have a shut off valve on the intake manifold that a heater hose attaches to. It resembles a faucet found in your yard.

If the **** (some types resemble a wing nut) is screwed all the way down, no water will flow to the heater core.

 

Not knowing where you live but a 160 is a cold running thermostat. Try a 192 if you live in a cold winter climate.

 

i live in chattanooga, TN and here in november we are still in the upper 50's lower 60s. lol as far as a/c i was told the truck originally had a/c, but i know it doesnt now. and i just drove it about 20 miles and everything is working just fine. so oh well i guess. but one more thing. the truck has no fan shroud, so it runs a bit warm when idling. a factory one wont work due to the 3" body lift, so would it be best to get an electric fan setup or to try and fab up some kind of a shroud (my fab skills arent that great).?

 

On heater issues I have a question too, I have heat and no defrost, is there a valve somewhere or sumthin' I can release, move, free-up, to get defrost? the dash levers move alright, btw, just nothing comes out of the defroster....thx for any response, idea

 

80F100man
A/C truck or non A/C truck? Non-A/C truck has a cable from the dash control lever to a blend door inside the heater plenum. A/C truck uses vacuum to move the blend doors. Much more complicated system.

 

99sbm
What engine are you running in your truck? A good shroud is necessary for proper system operation. Your choice, either fab one up or go electric.

 

its got a 302 in it.

 

Does the heater control panel on the dash have functions for the factory integral A/C?

If it doesn't, the only A/C's possible were either dealer installed or aftermarket.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
With factory installed integral A/C, there is this:

D4AZ18495A .. Heater Temperature Control Valve (Motorcraft YG136) / Available from Ford

MSRP: $28.72 / FTEpartsguy.com price: $17.23.

This valve is controlled by vacuum and is notorious for rusting shut.

When this occurs, no water can flow to the heater core.

The valve is spliced into the heater hose near the firewall-somewhat towards the passenger side.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~
With factory integral A/C, there is also this:

D5TZ19B888A .. A/C/Heater Temperature Control Selector Valve Assy. (Motorcraft YH285) / Available from Ford.

MSRP: $ 168.42 / FTEpartsguy.com price: $101.05

This valve mounts to the backside of the A/C/Heater control panel. All the vacuum lines connect here.

When you slide the lever on the control panel, this valve open one door in the plenum chamber, closes another.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~
D3TZ8146B .. 302 Fan Shroud / Fits 1973/79 F100/150 / Obsolete.

Green Sales in Cincinnati OH has TWO = 800-543-4959

Miller Obsolete Parts in Binghampton NY has ONE = 800-546-7278

Wesley Obsolete Parts in Liberty KY has ONE = 606-787-5293

That's it, no other obsolete parts vendor has one, no Ford dealer has one.

 

Btw, if your heater core is out it's usually leaking (from my experience)....look for a wet passenger side floorboard.

 

Non A/C .....inside the heater plenum??? ...how do I get to it then??....it just seems that door isn't moving.......thanks for the feedback too mate...

 

Heater plenum is under the dash passenger side of the cab. A few screws/nuts holding it to the firewall. The cable going to the door should be on top of it - find the plenum door and follow the hinge to the top of the plenum.