Last winter my heat worked great, it blows but doesn't even blow warm let alone hot. I figure its the heater core. One hose going to it is hot the other is cold. If I recall right when it worked, both lines were hot (warm). Normally I would just button up more in the winter but I use it to defog my windows and I cant see hardly right now.

A new one is only like 25-30 bucks, I got my haynes manual and read how to replace it. I just wanted to make sure that it is the heater core and how much of a pain in the a$$ it is to replace it.

(1987 f-150, 4.9L w/o AC)

 

yep! it's the core! You can try to backflush it first to see if you can blow out the junk that is clogging it. disconnect both lines and run water from the garden hose into the end of the return line (cold line). Direct the hot line out into a ditch or somewhere wher you don't care. this sometimes helps to get old crud out of the heater core.

if that doesn't work: Cut the antifreeze lines in the engine bay right at the end of the heatercores metal tubes. Don't even mess with trying to pull them off the old heater core unless they just slip right off.

Take off your glove box to expose the heater core box, remove the black cover to expose the heater core, pull old heater core out and push new heater core in.

Then I usually seal the heater core box back up with silicone... this isn't needed but will help the air flow out your defrost. If you don't get the box sealed up tight you end up loosing half your air flow onto the passenger side floor... the silicone is also sometimes need to seal the area around the heater core metal tubes going into the engine bay... the old black sealant that ford used will probably crumble upon pulling the old heater core out... You can also use expandable foam to if you happen to have a can open at the time...

Anyhow just wait for the silicone to dry/get hard and then stick your antifreeze lines back on!

Oh almost forgot!!! Make sure that your selector switch is opening and closing the blend vent door properly while the heater core box is all open and apart. Sometimes the cables will get sticky or you do something during this process to affect how it opens and closes the outside air blend door... I know this from experiance!

PS: I have been trying to find a better fan that will fit our trucks in order to move more air... The fans we have are really weak and don't defrost our huge wind shields very well...

 

thanks, I'll try the flushing thing first. I flushed the whole system few months ago during the summer but Ill try just doing the core in reverse flow. Thanks for the tips.

 

well if anyone see this... ANY ideas for a stronger blower motor???

 

I would use a heavy gage wire with relay directly to the battery for high speed. This bypasses all the smaller dash wiring with the loss of power through them. I'll be doing this with my trucks along with the headlamp wire upgrade too.

 

I just purchased a 1987 F150 and found that someone has bypassed the heater core. The replacement seems pretty straight forward. The problem is that I don't know which hose goes to which side on the core. Any help would be appreciated greatly.

 

Old thread...... , forgot about it!


Anyway, it really don't matter which side the hoses run to the heater core. Use new heater hoses AND hose clamps too.

 

Thanks! Logically I kind of figured that it would make a difference whether the coolant flowed clockwise or counter-clockwise but then again you never know. Good tip on the hose replacement also.

 

Thanks, I got this completed but now it only blows hot air. The ac was recharged recently and before the heater core replacement was working very well. I have also noticed that I can't move the slider for the temp all the way to the right anymore. This is a new development since the heater core went in. Any ideas?

 

Pull the access door off the heater core again and check for obstructions to the cable operated door and for broken vacuum lines on the vacuum operated door.

 

Most excellent points --- I've just done two heater cores (non Ford vehicles) that had mice squatters in the heater core areas........favorite hangout if you live in rural settings....