As always, I know I’ll get the information I need on the Forum, so here goes: my 61 Willy’s truck has the original style (I think) box heater. The last time I drove it in the early 90’s, it was not adequate to keep the windshield defrosted. We live in the high desert of southern Oregon and it gets cold here. The picture attached is the model. Any suggestions on a good substitute for this one that would work better and not require modifications??
Penny, if you convert the rating on the sticker of 2000 Kcal/hr to watts it is over 2300 watts. That is one heck of a lot of heat for a truck cabin. A 2000 watt heater can easily heat a 100 to 200 square foot room. With that in mind it has me wondering if the engine thermostat is operating correctly, or if the heater has a blocked core or restriction in the water flow somewhere. Do you know what temperature your engine is running at? A 180 deg thermostat should be perfect in the cold weather.
I suspect that the issue isn't the rating of the heater, but how heat gets sent up to the windshield. On the old trucks, the defroster was done through a vent on top of the heater box. The defrost is enabled by opening a little swing shutter to open and close those vents. It makes its way up to the vents under the windshield through a flex "dryer vent" type hose.
To operate the defrost, you turn on the heater fan, close the three doors on the heater and open the defrost vent. The fan in the heater box isn't very efficient in pushing air up through those flex hoses and you get a gasp of air somehwere toward the windshield.
On the '48, the heater will run you out of the cab on a 10-degree day at 40 MPH, but you still need a rag to keep the windshield clear.