Rebuilding a stock heater and supercharged fan upgrade

[sargentrs]

Project's down for the winter and I'm working on bits and pieces for installation next spring so I thought I'd do a write up on the stock heater box. It's held in place with 3 bolts that go through the firewall, from the engine compartment, and into brackets on the back shield of the heater. Remove the heater hoses and the rubber boot that connects the heater to the fresh air vent on the inside passenger kick panel. The only other things holding it are the diaphragm cables , the defrost ductwork, and an electrical plug on the end near the center of the dash. You'll probably want to remove the 3 bolts in the engine compartment to make it easier to disconnect everything else. It'll just about fall out into the floor board so have a 2nd set of hands there , inside the cab, to support it. Here's what it looks like on the bench. Mine's been sitting in the crawlspace basement under my house for the past 2+ years so it's pretty cruddy right now. That white you see is mold

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Once you have the box out, flip it on it's back to remove the motor. Only 4 screws hold the motor in place. Remove the screws and pull the motor out. There's a rubber gasket under the mounting flange so it might be sticky.

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With the motor out, you can see the motor resistor coil so be careful now that you know where it is. Flip the box back on it's face and remove the two screws holding the thermostat in place. Carefully remove the thermostat and set it somewhere safe, it's easily damaged.

[sargentrs]

You can see here the mounting plate for the resistor coil.

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With the coil out, remove all the screws around the curved shield on the back of the box, the one with the heater core pipes sticking out. Remove the heater core, it's just sitting in there, nothing really holding it.

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Notice that one of the water inlet/outlets is broken off. That's why I'm rebuilding it.

[sargentrs]

Now to remove the flat, back shield. Unfortunately, it's riveted in and you'll have to drill out the rivets. The levers that operate the diaphragms go through holes in the plastic housing and in this back plate. Carefully ease the back plate off while pushing the levers back through the plastic housing. I had to tap mine with a hammer and punch to get them to go through.

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There are two diaghragms. A small square one with a bent shaft and a larger trapezoid one with a straigt shaft, a channel bracket and a multiple bend linkage that goes through the channel. The small one comes out easily, the larger one is a little more awkward because it has 2 shafts that go through the back plate. Once you get the large one out of the back plate, you'll have to wiggle, twist, stand on your head, stick your tongue out and call a geometry major while you figure out how to get it out of the channel. I will come out without bending anything, you just have to get it turned just right. The diaphragms are covered with a foam gasket that is just glued onto the paddles. Mine practically fell apart in my hands and rubbed loose with my finger tips. Replacement gaskets are available so don't be overly concerned about destroying them.

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[sargentrs]

After I got mine disassembled I decided to clean it up and paint it. There was only mild surface rust so a quick brushing with a wire wheel on my drill and a wipe down with Prep All. Then sprayed some self-etching primer and black Duplicolor on the steel parts and Duplicolor Vinyl paint on the plastic housing.

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Waiting on my new heater core to come in and I'll start putting it back together. I've also got the parts ordered to do this heater fan upgrade http://www.fordification.com/forum/view ... &sk=t&sd=a. More to come soon....

[jimmy828]

I was lucky on my heater box. Was not much to do but check everything out and clean and paint. When i pulled the fan out to check to see if it was ok, it still had the original fan and was marked 69. After i painted it. i took a flat top pencil eraser and dabbed it in white paint and and applied it to the raised letters on the box. Made a heck of difference in appearance.

[sargentrs]

Thanks jimmy! That's a good idea. I didn't even realize mine had words on it til I cleaned it n painted it.

[sargentrs]

Now that everything's painted, let's get the motor mounted. Following the "Supercharged Heater Fan Upgrade" directions, I bought this motor http://www.summitracing.com/parts/fss-35502/overview/, this blower wheel http://www.summitracing.com/parts/fss-35535/overview/ and I also bought this gasket set http://www.lmctruck.com/icatalog/fb/full.aspx?Page=42 (item 43-1054). You can see here the difference in the old and the new motor/wheel. Just take the mounting flange off of the old motor (2 nuts) and fasten it to the new motor. Perfect fit.

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I first set the wheel in the housing to check for clearance. I think this wheel is even bigger than the one in the "Upgrade" thread. It's a pretty close fit but there's enough room to position with about 1/16" clearance around the wheel.

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Just in case I decided to go back, I really didn't want to cut the hole out larger. So, after about 30 mins of two handed juggling, I got it positioned where it wouldn't scrape the housing or the venturi panel back. I was able to two of the mounts near the original holes (by redrilling right at the edge) and had to redrill the other two. The U-nuts just grabbed the edge enough to clinch tight enough to hold on.

[sargentrs]

Once I had the new holes located, I put a dab of contact cement on the new foam gasket and seated it on the motor mounting flange then bolted the new motor and gasket onto the housing,

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then attached the blower wheel and tightened down the set screw. Here's how the blower wheel sits inside the venturi intake.

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I gave it several test spins during this whole process to make sure it wasn't scraping anywhere. Using contact cement, I put new foam gaskets on the diaphragm paddles.

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[sargentrs]

Then located the paddles back in the holes in the back panel.

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Now comes the tricky part. I've gotta get the 3 rods on the paddles to line up with 3 holes in the housing with the back panel in place. So after finagling for about 20 minutes, I finally got all 3 pins lined up and the back panel on. Gave the wheel a spin while flipping the levers and uh oh, the flap hits the wheel.

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So do I send the wheel back and hope the next one is small enough but bigger than the old one? After careful examination, I figure I can knock about 1/8" off the flap and it'll clear while still closing off the air passage.

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Now everything seems to work fine and I can screw down the back panel.

[sargentrs]

I got this heater core from Summit Racing. http://www.summitracing.com/parts/pli-399024/overview/ It was a perfect match and $5 cheaper than LMC's. The heater core just sits in the end of the housing.

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The gasket kit from LMC comes with 2 rubber like square pads with holes in the center. I'm assuming they go over the pipes although my original had nothing like them there.

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Once in place, slide the back cover over the end of the pipes and screw it down to the housing.

[sargentrs]

Stick the blower resistor back in and screw it down. A quick check with a hot battery and the motor spins freely. It puts out a lot more air flow and it's quieter too. Because of the more powerful motor, wiring it up for installation will require the addition of a relay for the high speed mode. I borrowed this from the "Upgrade" thread and thought I should post it here too.

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I recommend this mod to anybody not satisfied with the current heater in their truck. Thanks to knightfire83 for posting the original thread! Hope somebody finds this useful.

[KRob]

Which blower wheel did you get....both links go to the fan motor. Looking forward to see how it works for you. I need to beef up my heating system....its cold up out here in Eastern Oregon.

Thanks

[sargentrs]

Ooops, sorry about that. Fixed it up there but here it is again http://www.summitracing.com/parts/fss-35535/overview/

[Mancar1]

I sure should add this heater mod to my to do list. The stock heater just doesn't hack it well on a cold frosty morning. Great job.

[motzingg]

great post! good motivation for me to tear the thing out, knowing what is inside it.