2002 F-350 4x4
Heater seems to only work sometimes.
Can hear it blowing and making heater noises but nothings coming out the vents.
Sometimes by shutting the truck off and starting it back up the heater works.

The airconditioner did the same thing a few times last summer.
I can live without the airconditioner but up here in BC I kind of need a heater this time of the year.

 

Sounds like you have the old vacuum leak problem.Check the sorry tubes that go to your auto hubs.If you grab them and black rubs off on your hands go ahead and replace them.You can use 1/4'' fuel hose.
Does your vac pump run when you turn the key on?If so,it could be a bad solonoid(Pulse Vacuum Hub Solonoid).The solonoid is mounted on the passenger side fender.Check the other vac lines as well.

Check out post #11

https://www.ford-trucks.com/forums/8...uum-leaks.html

 

If its the lines going to the hubs does that mean 4x4 wont work either?

 

I have the same problem and I will have to trace back from hubs as well. How much does the vacuum pump cost from the dealer if it turns out to be that?

 

When you turn the switch for the ESOF it will default and not pull in the hubs.Then you have to get out and lock them in manually to be in 4x4.

 

Diesel Site's got a really nice set of braided stainless steel vacuum lines for the front hubs, for a little more than half a C note. That will, or should put an end to that problem for a long time.

 

So now its getting real cold , like -25 so i gotta fix this thing.
These hoses you speak of , do they run from up under the hood all the way down to the hubs?
Or where are the hoses?

 

I read that link, and it says the heater defaults to defrost.
My heater doesnt default to anything it just blows away( You can hear it) but I dont get any hot air.
I think a heater door isnt opening all the time because sometimes it seems to work OK.
Does that ring a bell with anyone?

 

This seems like a totally different problem. Theres that part thats on your input heater line hose, a heater control valve, its inline with the hose going from the waterpump to your heater core. I believe if you loose vaccum to this part it won't allow heated water to the heater core. Reason I'm thinking that is because you say it happens on and off like the air and it would be a good thing to check for a vaccum leak going to that heater control valve. Just throwing some things out there, might get lucky. Here it is More Information for FOUR SEASONS 74857 and more for different hose diameter RockAuto Parts Catalog

 

Thanks ill see if I can find that.