Learned today that the heat in my '91 F150 XLT 4x4 doesn't work. Is it just the heater core or possibly something else? I don't like throwing random parts at the truck until it is fixed. How hard is it to replace the core in these trucks? Do you have to remove the whole dash or can you get to it from the glove box? Any tips would be appreciated!

 

What engine? Are the heater hoses connected to the core? Is the coolant topped up? Factory A/C? Do you hear the blend door moving as you slide the temperature control? Does it feel like it's swinging a door?

. .

Changing the heater core on '80-96 trucks is slightly harder than changing a headlight bulb.

.

 

Sorry, the motor is a 5.0 with auto tranny and factory a/c that does not work. The switch and the control seems fine, I'll check the hoses and core to make sure all else is well.

 

You can hear the door that Steve's talking about when you move it from cold to hot, etc. If you hear that, then it's most likely the connection (hoses) to the heat core or the core itself. I was reading around online before and thought I saw something where you can switch the 2 hoses (at the core) and it will push and debris out of the core that might be cloggin it up. I've never had this problem, but I believe in researching something just in case I do have the problem haha. I'm going to go look and see if I can find that caption that explains the hoses thing.


Ha, I'm loosing it. I read that in this thread! Wow. I amaze myself sometimes hahahaha Steve's captions will explain it to you.

 

WHICH one, though? Read this caption:

 

Played with the switch this past weekend and it does correctly move the air from vents to floor to defrost and it sounds like I do hear a door. I removed the glovebox door but that is where I stopped. I will get the tranny code after work today.

 

Transmission code is: E so that means E4OD correct?

Thanks

 

You don't know how many times I have heard people chasing heater problems just to find that the coolant needed to be topped off. Start there.

 

Yep.

 

Well the truck run constantly under the NORMAL mark so I'm planning to drain the fluid, replace the thermostat, and replace the core (they aren't that exspensive) and then refill and see what happens. The switch seems to be working fine and I do hear the door when going over to heat. Thanks for the help, if I'm missing something please chime in.

 

I'm having the same problem on mine. What is this door noise ya'll are talking about?

 

Changed the thermostat this weekend, the one previous owner put in was upset down! Truck finally makes it to the normal on the gauge. Next weekend planning on the heater core as it must have a leak cause I see where the previous owner put in a way to block the fluid from getting to the core. Anyways, thanks for the help...

 

chances are if the fluid is topped off and everything else is running right they probably bypassed the heater core. check and make sure the hoses are running from the water pump to the firewall. could be something simple as that. also a lot of guys install a stopper in line of the heater core hose like they did on my truck. if yours has one make sure its open. a lot of the southern state guys do that to block off all the heater to prevent the cab from getting hotter than it needs to during the summer.