These are the final photos of the finished lower heater rebuild using the "Blazer Motor Upgrade".
Following is a description of the disassembly and reassembly and a list of parts used in the process.
- Fan Motor: Napa BK 6551039
- Spring: Ace #102
- Push Nuts (for damper pivots): Dorman 961-345D - found at O'Reilly's
- Foam: McMaster #86225K53 1/4" w/adhesive (24" square)
- Foam: McMaster #86225K57 1" w/adhesive (24" square)
- Eastwood Flexible Strip Caulk 13524
- Rubber firewall spacers: 20Pcs Black Rubber Bumpers J9B4
- or Rubber firewall spacers: 8Pcs Black Rubber Bumpers RH-1606-8-A 1.5"Dx.82"H .25" Hole
- Firewall Hole Saw: Irwin (mandrel type) 3 5/8" diameter
- Metal Paint: Rustoleum Satin Black Professional
- Plastic Housing Paint: Dupli-Color low gloss engine enamel (wipe with lacquer thinner first to promote bonding)
- Heater Core: Autozone Transpro #846071-399210 (make sure it has the silver L-bracket welded onto the hose side)
Removal: Open glove box door, remove inside box insert. Unplug fan resistor wires, disconnect control cables from door levers (only the ones that come in from the dash). Remove the defroster duct flexible hose from the top of the box. Go under the hood. Disconnect the wire from the blower motor, heater hoses. Remove the nuts from the studs that hold the box to the firewall, don't forget the one behind the valve cover. Go inside the Jeep, pull the box back and may have to tilt it down in the rear a little to clear the firewall. I had mine out in about 15 minutes.
When I reinstalled mine, I put a self-tapping screw into the blower motor mounting flange and ran a wire from that over to one of the heater mounting studs at the firewall.
Disassembly
Disassembly: Battery tray.
Disassembly: Fender/battery tray brackets.
Disassembly: Fender/battery tray brackets.
Disassembly: Firewall coupling nut ground connections/heater hose connections.
Disassembly:
Disassembly: Remove glove box.
Disassembly: Remove seats (unless you are a contortionist).
Disassembly: Heater hose connections.
Disassembly: Taped a small bucket to firewall to capture coolant.
Disassembly: Hung heater hoses to hood to prevent further coolant drainage.
Disassembly: Disconnect heater control cable and defroster duct.
Disassembly: Lower heater box; back. Note: dried and cracked rubber mounting spacers.
Note: Four mounting bolt locations (one is directly behind valve cover).
Disassembly: Fresh air box; top. Note: gasket.
Disassembly: Fresh air box; top. Note: gasket.
Disassembly: Defroster duct; top. Cable brackets.
Disassembly: Defroster duct; top. Cable bracket.
Disassembly: Heater duct; bottom. Cable brackets.
Disassembly: Heater duct; bottom; duct speed nut and screw. Cable bracket.
Disassembly: Interior defroster damper/washer.
Disassembly: Interior heater dampler, cable connection/lock washer.
Disassembly: Cable bracket and cable clamp.
Disassembly: Cable bracket assembly.
Disassembly: Fresh air box; cable connection.
Disassembly: Fresh air box; right side
Disassembly: Fresh air box; left side; metal washer and spring washer.
Disassembly: All lower heater box parts
Utilizing two existing holes in the firewall, secure a piece of plywood to the firewall and mark the center of the existing motor housing hole using a circle template. Drill a pilot hole for the mandrel hole saw. Drill new hole with 3 5/8" diameter bit. I ultimately filed off the sharp points where the two motor and electrical connection holes converge. Before proceeding, I test mounted the back panel with the motor mounted and the fit was good. File opening and use black liquid electrical tape to finish the edge of the new hole.
Reassembly
Disassembly: New fan motor on left, OEM fan motor on right
Lower heater box back panel painted and new motor installed. Used the rubber feet listed above for the firewall spacers.
Lower heater box back panel painted and new squirrel cage mounted. The Napa motor shaft is a perfect fit.
Painted dampers and cable bracket.
1/4" foam on dampers. Make template before removing old foam. Scratch an awl line on damper before removing to use as a guide in placing new foam.
New 1" foam gasket (bandsaw worked great, coping saw on large inside hole, 3/4" hole punch").
Laying out holes required some drafting skills, and a compass. Laid it out on the paper backing (make sure to lay it out in reverse).
Inside heater box; pre-assembly.
Decided to use Eastwood Flexible Strip Caulk (also known as "dum-dum") instead of RTV to attach the front heater box to the rear panel. May use it to seal the Upper heater unit to the cowl as well. Does not harm paint, stays pliable and fills gaps well.
Lay out the strips in the middle of the seam and around each screw then screw the back panel to the front plastic housing. Fill in with more caulk where there are gaps. I used a wet finger to smooth out the joint much like household caulking.
Here is the new foam gasket that will fit between the upper and lower heater unit as an air seal.
Finished front.
Finished rear.
Next will be the upper heater unit.
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