My '68 F250 is fogging up. Unless I wipe the windshield and the side and back windows bone dry with a cloth, the defroster has little or no effect on the moisture.

For example, I warmed up the truck for 10 minutes with the defroster blowing, which managed to clear a part of each side of the windshield the size of a half-dollar, while the rest of the windshield, the two side windows, and the rear window fogged more. I wiped the windshield down, leaving only a trace of moisture, and drove off. Within a mile, the windshield fogged up completely, as did the side windows and rear. I had to pull over.

After an hour of nursing the truck home, while drying the windshield continually, I sat idling in the driveway, running the defroster. Nothing changed when I switched settings. I wiped again--this time bone dry. The windshield started fogging up immediately, with the defroster working marginally after a half-hour: first, clearing a small spot, and then very slowly clearing about one-third of the windshield.

During all of this the defroster blew strongly, and the cab was very warm, almost uncomfortably so. I tried all of this a few times with the windows up and down, while driving and when idling--all to no effect. During all of this, neither the heat from the defroster nor the heater had any effect on the side and rear windows; they remained wet and opaque.

As for weather conditions, it was dry and about 45 degrees.

Thanks,

Steve

 

You, sir, have a leaking/seeping heater core by the sounds of your description. Not a hard thing to fix on your own (as long as you don't have air conditioning) with a few simple hand tools and at least enough knowledge to know what end of a screwdriver does the business. The folks here can easily walk you through it. To have someone at a regular shop fix it for you, be prepared to bend over and grab your ankles for having a $30-$40 part replaced!
My $.02,
Gene

 

Thanks, 68 Horses. Anyone care to walk me through the steps?
I noted, but did not mention in the thread, a little water trickling from the bottom of the heater housing into the cab.

 

Actually, I would really appreciate some guidance. I have had the truck in the shop a few times this year; in fact, I just got it out of the shop, for unrelated reasons, the day before yesterday.
Regards,
Steve

 

the "heater box" contains both the fan and the heater core, you can likely see the motor underneath the glove box area....

Under the hood, disconnect the 2 lines that feed coolant to the heater core (both on the passenger side of engine, going through the firewall.

Then, remove the nuts that hold the entire heater box to the firewall....there are 3 or 4 as I recall, mine were those stamped steel nuts....

The heater box then comes apart in 2 halves and you can remove/replace the heater core. You may want to take a moment to wash out any coolant residue in there while it's out.

Installation is just the reverse of above (and I probably forgot to mention something....but it ain't that hard to figure out....know that the whole box comes out is most of the magic!)

 

the other post are right on..I just wanted to say be carefull with the two large air ducts that go up to the top they are easy to break just unsnap the rings and handle them carfully so you dont need new ones.Its a easy job...good luck bill

 

Yeah, one of the good things about older vehicles is you can be your own mechanic. And you should be your own mechanic.
You know if you roll the windows down the cab will defog.
Get your heater core, maybe someone here can tell you where to get a good one. Mine came from NAPA, and it was kind of wimpy.
Take out your glove box liner.
You might want to put a crayon mark on the rubber bezel that connects the heater box to the side of the cab for reference.
Under the hood, remove the heater hoses from the heater at the fire wall.
You can mark left and right if you want.
Once you loosen the clamps, break the hoses loose, by spinning them with a pair of pliers.
Be prepared for coolant to come running out.
The heater is basically held in by the three little studs that protrude through the fire wall. Remove those three nuts and washers.
Go under the dash, and wiggle the heater box loose. Pull it down so the heater core and studs are inside the cab, and it should come apart from the rubber bezel.
The heater box is still hanging on by the defroster tubes. Unbuckle those, and disconnect from box. The wire loom plugs into box, unplug wire.
The heater control cables need to be disconnected, but try to get an idea of how they work, and push the control levers all the way to one side before disconnecting.
You should now be able to finagle the the heater out of the cab.
The first step is the learning part. I will be back soon with the rest.

 

Another small suggestion, it works for me when ever I jump into a task I'm not familiar with. If I'm working on a vehicle that does not belong to me I go to my local library and check out a Chilton's manual, if I own the vehicle, I buy a manual, they're usually around $20.00. They're a great source of information with a few pictures. Sometimes some steps are kind of vague, and You have to figure out some steps for yourself, but an old Ford pick up heater core replacement is a pretty easy job.

 

Ok, I'm going to try to install one myself. I found the part, a Chilton manual, and I've printed this thread. It makes sense, even to my inexperienced self, to do-it-yourself whenever possible. I'll post a result, good or bad, when I'm done.

To Victor L: I kept both windows fully open for 15 minutes with the defroster running--no improvement.

 

I've read all the threads in this forum on heater core, and per some suggestions, I'll also flush the radiator and replace the heating hoses. I've had to replace other parts because of the truck's age, and I'm sure the heater hoses have limited life after 42 years.

One note, however. Virtually every start of a heater core thread complained that there was no heat, which is not a problem of mine; the defroster/heater blows hard and hot. For the time being, my issue is limited to a persistent condensation on all windows and a slight trickling of liquid at the base of the heater casing inside the cab.

If that's enough to warrant a heater core replacement, I'm ready to start.

 

Nobody mentioned yet that it will be a good idea to drain the radiator before you start this job and give the rest of the cooling system a flush before putting in the new core, and then refill with new 50%/50% antifreeze/distilled water. NEVER, NEVER use tap water in your cooling system due to contaminants and minerals. I also suggest you make up your own 50/50 mix as opposed to using pre mixed, as who knows what anti freeze companies use for the water. Also a good time to replace your heater hoses (cheap) and radiator hoses if they look questionable. A good way to flush is to put you garden hose nozzle into one of the disconnected heater hoses (the one that connects to the water pump) disconnect the lower radiator hose from the radiator, turn the hose on to medium-slow and start the truck and let it and the hose run for a while, keeping an eye on the temp. Once the water pouring out of the radiator is clean, you're good. In other words, while replacing a heater core is a good time to do a complete cooling system service and then you shouldn't need to mess with any of it again for a year or two when it's time to do an anti freeze change. A good service (hoses and all) can last for 5-7 years except for changing the coolant every couple years.
HTH,
Gene

 

check out this thread i have i'm actually restoring my heater box in my 71 f250 as we speak. let me know if you have any questions or need some pics of anything. https://www.ford-trucks.com/forums/1...questions.html

 

Crazed87Bronco,
Thanks for the link to the pictures. I didn't know what any of those things looked like. I will probably start the project on Tuesday. I have another thread on the same vehicle, which will require some attention tomorrow, then I can get to work on the heater core. If I have questions, I will ask. I appreciate everyone's help.
Regards,
Steve

 

Later today I'll start the process of changing the heater core. My plan, as it were:

(Check the conditions of the heater hoses and the radiator hoses, replacing them and their clamps if necessary.)

First, drain the coolant; remove the heater core, following the instructions from the thread and the Chilton manual; replace the core and reverse the process, during which I will change hoses and clamps where necessary. Once the new heater core is installed and the system sealed up, I will flush the system.

I've watched some videos of a Prestone system in which the inlet heater hose is cut, a Tee is inserted, and the system is flushed through the inlet hose, using a backup preventer and a garden hose. Is this a recommended way to do this? It appears that the installed Tee is then a permanent part of the hose.

Any comments would be appreciated.

 

I would bypass the heater core while flushing the system you don't want dirt/debris going through your new heater core and clogging it up I would connect the in/out heater hoses together to make a loop around to bypass the heater system