Team, I am wondering what options may exist to provide a heater/fan setup with the factory heater core and fan removed. Is there anything aftermarket?

My problem is I have a factory A/C car that had all the A/C equipment removed before I bought it. I don't particularly want or need an A/C and I am going for a flat, smooth firewall. Ideally, I would still like the ability to de-fog the screen if necessary. Is there a solution?

You are not going to be able to defog the windows WITHOUT A/C. The A/C system produces DRY air and that is what defogs windows. No matter what you do, without A/C, the fog is going to return. I have the same issue when it's raining. No matter what I do, even with heat, it doesn't go away. That is why WHENEVER you turn on the defroster/defogger, the A/C turns on with it, provided the car has A/C. No A/C, no defogging.

I've seen heat-only underdash units from one of the aftermarket AC vendors, don't remember which. (Vintage Air, Hotrod Air, Classic Auto Air?)

There's also someone that makes a heat-only box designed to go under the seat in a Jeep.

Heaters DO NOT produce DRY AIR. It's the dry air that defogs your windows and the only way to get dry air is with an A/C system. Unfortunately, without A/C you are just spinning your wheels. Buying a heater system is not going to help your problem.

this is one particular brand like what Jon mentions:http://www.maradyne.com/maradyne_mobile/products/heaters/index.html
we use them in construction equipment, where the factory unit has failed and O.E.M. replacement stuff is thru the roof~pricey.
if one has all of the stock unit removed from under the dash, I don't see where install would be a major snag, and the outlets are ported where flexible hose or tubing could be run up to the stock defrost ducting.

i have a lot of cars without a/c, and magically i guess, the defrosters work?

The amount of moisture that air can hold goes up with temperature. If you heat the air, the relative humidity of the air drops and it can absorb more moisture from the windshield. However, the air is getting cooled by the windshield at the same time. If you get a big enough volume of air, or you pump enough heat to warm up the windshield, then the defroster will work even without an AC evaporator condensing water out of the air. However, it'll work a LOT better with AC.

rain-X on interior and exterior front glass...........you wont need the wipers either.

rain-X on interior and exterior front glass...........you wont need the wipers either.

Do you use Rain-X or Fog-X? I have never tried Rain-X on the inside nor have I ever tried Fog-X.

With heat only, all you are doing is blowing the humid air straight onto the windshield. The A/C is what removes the humidity from the air thus defogging your windshield. I have had the windshield fog up using the heat alone in a car with A/C. I have had to activate the A/C while the heat is on just so the windows wouldn't fog up. It's the dry air that removes humidity so no matter how fast or how much heat you produce, if it's not dry it's not going to defog. My Roadmaster moves a VERY LARGE amount of air on the high setting and no matter what, when it fogs up, I have to activate the A/C.

i have a lot of cars without a/c, and magically i guess, the defrosters work?

Its really amazing on how physics works.
Hot coffee cups don't sweat (heated windshield)
and cold Ice Tea glasses do sweat. (cold windshield)

DRY air is not needed, its the temperature differential/humidity. Ever wear glasses and get out of the car and instantly have fogged glasses?
Its caused by the dew point.
The cold glasses fog from the humidity. Yet once your glasses heat up, no more fog.


Is dehumidified air nice to have, yes. But its FAR from the cure all. At best its a minuscule part of the equation.

Charlie - I have lived on the coast and in heavy winter rain conditions most of my life. Under most conditions you don't need AC for the defroster to work. I have seen certain conditions where it's just like you say and it's caused by what I will call moisture impregnated interiors. Under these conditions it takes a towel kept in the car to wipe the inside windows down along with the defroster running unless the car has AC. The thing is it's not like this on every car, I've owned dozens of cars and trucks without AC and only had defrosting issues on a couple.

My reasoning is these moisture impregnated interiors are caused when water leaks into the cars or windows have been left down so moisture can get in. It doesn't take a rain storm with the windows down, just some heavy fog a few times. This could even be caused from driving around with the windows down or on a ragtop the top down in fog or light rain. It could also be slight windshield and door window leaks where water ends up collecting where it can't be seen. The door windows in my El Camino were part of the cause for it. The proof is the bottom of the doors were rusted out but there was no other rust anywhere on the car. On that car even the AC didn't help the defroster much.

Here's one for you, my '69 ragtop doesn't have a heater core, just the fan and I can defrost it's windshield just fine.

Anyway some cars have a moisture issue and you are right AC helps big time, a lot don't though and AC isn't necessary, warm air does the trick... Can we please get back on topic so our Aussie friend can figure out what to do about a heater fan for his situation...

Wow, I stirred things up a bit here didn't I.....

Interestingly, the reason I am looking for this solution is actually not just to de-fog my windscreen. I may need to get my car past a police roadworthy inspection to get it re-registered and one of the things they look for is that the car must have a working heater/fan setup. If it doesn't it may not pass.

keep a 12 volt hair dryer in the glovebox (or whatever you guys call a glovebox down there)..
you can also buy a nifty little heater that plugs into your cigarette lighter and sits on the dash, too. every year at about this time, Wal mart always gets them by the crate load.

as for the "you need AC to keep the windshield clear" thing- i guess all those cars i've had over the years without functional AC kept the windows defogged via some sort of black magic or something. usually, just having air blow over the windshield clears away fog and keeps it away- and not even heated air, just air. live in MN- the land of 10,000 lakes and 95% humidity- for any period of time and you start to see what works and what doesn't. the only benefit of using AC to defog the windshield is that the value of oil company stocks you own thru your 401k plan at work goes up from the extra gas you use.