fire in heater

[Mikeallsport]

My wife and I were out for a last ride in my 67' 327350 convertible when I decided to turn on some heat for the first time this year. We first thought that someone was burning leaves near by and we were right it was in our heater. Smoke poured out but there was no where to shoot the extinguisher. We unplugged the blower which was cool to the touch and the fire persisted for a while before burning itself out. Must be from mice building a nest and chewing the insulation off some of the wires? Now I have to get into the heater box and get things repaired .My local corvette buddies urged me to take it to someone and have it done because its "very difficult to work on". I am going to do it myself. 1. Any suggestions or short cuts on how to get it out rebuilt and back in? 2. Should I replace the heater coil while I have the thing apart? 3. Is dull green the right color for the side walls under the dash on a black body with red interior? It's been 30 years since I last turned a wrench and would appreciate any help!!

Thanks!

[Gary S.]

Re: fire in heater

Mike, the heater box on mid-years is not that difficult to get into. When I had to replace the heater core on my 66, I had it out in probably one hour. It took another hour to to remove the inner box. Dr. Rebuild sells a pretty decent seal kit, if you don't mind dealing with him. The hardest part was that we were dealing with very old fiberglass parts and I was desperately trying not to damage anything. If you will go back a few issues of The Restorer there is a very good step-by-step on doing this very thing. Good luck, Gary 21316

[John R.]

Re: fire in heater

With respect to your question about the dull green color, check to see if the paint number on the trim tag beneath the glove box is 983. It sounds like your car may have originally been painted Goodwood Green.

[Michael W.]

Dumb question

From my limited knowledge of midyears, there are no wires inside the heater box itself. Being that the heat comes from a from a hot water core and not from electrical resistance, are you sure that you actually had an electrical fire inside the heater box?

You may want to check under the hood along the firewall for damaged wires. If nothing is found, try vacuuming out the heater ducts for any debris that may have been ingested. Unless your core is leaking antifreeze, I would be tempted to leave it alone.

Mike

[John H.]

The Culprit Is....

Most likely the heater blower resistor, which is mounted to the inboard side of the blower housing, adjacent to the rear of the passenger side cylinder head. It has coils in it which function as resistors to provide the different blower speeds - the coils get good and hot, and that's why the unit is mounted in the airflow path, just before ambient air reaches the heater core. When you turned the blower on, one of the coils got hot, and apparently ignited whatever debris had found its way into the air inlet and set up housekeeping in the blower housing. I doubt if the heater core itself has been damaged. The resistor mounts with two screws to a hole in the blower housing that's about 1-1/2" x 2"; possibly you can remove the resistor and use a mirror to look through the hole to see what's inside, and maybe vacuum it out before taking on the job of removing the blower housing.

[Mikeallsport]

Re: Dumb question

THANKS for the help guys!! I bet the resistor is the culprit for the fire! As far as the green paint under the dash the tag indicates that the original paint was black but I know these tags can be changed. It looks like primer under there. Anyone know if GM ever used green primer od is this wishful thinking? I bought it as an all original car! I love the car anyway but would still like to know the origin of the paint!!

[Shane G.]

Green primer

The "dull green" you are seeing under the dash is a type of primer used by GM on the Metal reinforcements, and is IMO normal and expected. Shane

[William C. Brown]

Re: fire in heater

Not sure about the job on a 66, but my 68 was a piece of cake! 6 nuts hold the blower cover on (in the engine compartment). The bolts for the nuts are part of the heater box assembly. Once the nuts have been removed from the blower cover, the heater box can be easily pulled out (after you remove the cables!) Mine had dried leaves and other pieces of junk floating around in the box. It's easy to clean out and just as easy to get at the blower motor resistors, too.

Good luck!

--Corey #33787

[John H.]

Re: Green primer - Zinc Chromate

The green primer is normal - it's zinc chromate, which was sprayed on the birdcage (in the basement at St. Louis) after welding ( well before the days of electrically-charged black uniprime dipping of welded raw metal assemblies). Corvettes didn't have dip uniprime until we tooled up Bowling Green in 1981 and built a modern paint shop from scratch. The paint shop at St. Louis was only one step beyond Kem-Tone and rollers - good thing the body was fiberglass or they'd all be gone by now. Can't use the green stuff any more - now classified by EPA as toxic hazardous waste, even in the form of dry sludge.