Whenever I drive my 98 the windows fog up and if I turn on the defrost it just gets worse and smells horrible. Does anyone have any suggestions to fix this or what it could be?

 

Your heater core is leaking...I'd bet there's a mess on the passenger side floor, too...
Fairly easy fix, {EDIT! YOU SAID 98, I SAW 89, duh! I DON'T KNOW HOW COMPLICATED YOURS IS} go to the parts store and get a core and Chilton's/Haynes manual, you'll be done by dark! (well, maybe)
Good luck!!

 

Changing that heater core is a nightmare. The A/C has to be recovered & evacuated, and it's not even easy to get at. The connections are buried behind the battery under the accumulator. It's a total nightmare.

I'd almost rather bypass the heater core & install electric heaters.

 

I'm having the same problem.Mine is in the shop right now for this.
Does yours do this all the time?
I don't have any anti-freeze in the floorboard,the smell isn't quite an anti freeze smell.It's more of a musty smell.Sometimes,on colder mornings,smoke will billow out of the vents like the thing is on fire.
The reason I ask if it's all the time is,the service manager told me that if the heater core were leaking,the windows would fog all of the time.Mine seems to only do it in the morning.

 

It's possible to have such a small leak that it only occurs under certain conditions. The one in my '94 CV was like that - until it blew out on the highway.

 

Very true.
Just got off the phone with the dealer and of course,it can't be duplicated.
They cleaned all the windows and are going to try again.
I hate intermittent problems.

 

The service department was finally able to duplicate the problem and yes,it's the heater core.She mentioned electrolysis and asked if I worked around high voltage lines.Of course,I don't and we've all read about the KNOWN electrolysis problems.Thanks to this site.It's been a great help with this.

 

What a moron. Being near high-voltage has NO EFFECT on "electrolysis", which isn't even what's happening. The actual process is "galvanic action", and it's purely an effect of old coolant; especially if your truck has "long-life" coolant - that crap doesn't actually last as long as "regular" coolant.

 

My core starting having problems at 36,300 miles.The coolant isn't even old.I waited till 38,676 to take it in,thinking that it might condensation in the system burning off.
One thing's for sure,the new orange coolant smells terrible when leaking like that.It doesn't have the "sweet" smell like the green coolant has.More like a burnt coffee smell.

 

You "do not" need to drain,evacuate and recharge the air conditioning system. If you do it yourself, be prepared for an all day job.

 

So which year truck am I remembering having to do that on? I'd have sworn it was a '97-04.

 

It has to do with current flowing through the liquids. The only reason why the coolant has to do with it, b.c the longer any coolant is in the system, the less protection properties it has, and it is dirtier and wears out parts in radiator first. And basically electrolosis is current passing through a liquid, and grounding out on the other side of the metal object, and it will actually eat through the metal.

And im pretty sure you have to pull a vacum on the AC lines
-Patrick

 

There is no need to touch the AC on the truck to change the heater core. I am on #8. The Expedition and the F-150 are the same. The only difference is the floor console if your Expi has one.


JMC

 

Basically, electrolysis is the decomposition of a liquid solution by electric current. If that was what was happening, the COOLANT (the solution) would be breaking down - not the heater core. "Lysis" is a Greek word that means "to cut loose". Note that this term is NEVER applied to solid materials - only liquids.

Galvanic action is the phenomenon of an electric charge developing between 2 dissimilar metals in contact; either directly, or through an electrolytic solution. It's named for Luigi Galvani, who first researched the effect. This is what makes thermocouples & lead-acid batteries work, and what makes salt water eat up boat motors that aren't built for it. Note that this term applies to solid metals being corroded or deposited electrically.