Bart McNeil posted on the CJ-3B Bulletin Board: "My '53 has a Harrison heater as seen under the dash on this rear 3/4 view from the Parts List (60K JPEG). Almost the whole heater unit is visible in the illustration. In the rounded top part is a fan which draws air from between the heater unit and the firewall, sends it down and through the coils (if that's the term) and out an unseen opening in the bottom and through the two ducts directed at the driver's side. My heater blower doesn't seem to work. Could be the switch, could be the wires, could be the motor. Where's the motor? On mine a motor about the size of a Foster's Lager can is installed on the circular mount at the top of the heater. I don't see a motor in the illustration. Is mine wrong, or is the illustration incomplete? On a Jeep without a top I don't suppose it makes much difference whether there is a motor on the heater or not but where would one look for a new motor if replacement is necessary? Is it a NAPA-type item?"
John Hubbard: "The circle on the top, front of the heater is where the only motor resides. There are two screws that hold the motor from the front. I don't remember how it attaches from the rear -- the middle of the circle in the housing (as seen from the front) is the where the shaft of the motor is located. I do not know of any kind of OEM or dealer-installed auxiliary motor available for these early-style heaters.
"With the 6V motor on mine there wasn't a lot of heat output. I pulled out the motor and found a 12-volt motor (that we already had) that matched exactly (dimensionally) and now with a 3-position fan switch, even on low there is a lot of air movement -- hot. Of course cleaning out the core helped a lot. I also used an aluminum 5-bladed fan as a replacement on the shaft of the new motor (instead of the steel 4-bladed fan)."
See also a bottom view showing the core, and a closeup of the Harrison serial number tag on the back (30K JPEGs).
"The heater I restored was used, and had been stored (maybe the whole Jeep) in a chicken coop. So the fins of the core itself had fecal matter all over them. I basically sandblasted the outside and pressure tested the core. The core had some type of sediment/debris inside and that was removed. I don't know if they use chemicals or actually take off one end and rod out the channels, like they would do to a radiator. If the core doesn't leak and puts out enough heat -- i.e. gets hot to the touch -- then you should only have to worry about the amount of air that can be moved across the fins -- i.e. the fan. Since you don't want it to leak, at least get it pressure tested or test it yourself -- maybe 10-20 psi or something, with an air tank.
"Then get your 12-volt fan, new switch and wiring, and you are set. Willys Overland in Toledo has all the electrical stuff (NOS) if you want a 100% restoration. The original switch was a 3-speed bakelite device. I don't know if they have fan motors though."
Joel Kamunen: "These heaters are not exclusive to Willys Jeeps. The old fellow who restored my Jeep about 15 years ago spotted a heater in a late forties Chevy auto and it's in my Jeep. Any radiator shop can get it cleaned out for you or you can use Draino drain cleaner (sodium hydroxide). If the core is thin, the cleaning process may develop leaks, as will putting pressure on it, so don't go too high on pressure testing it."
Tom asked: "I've been looking for info as to the color for the Harrison heater on a '55 CJ-3B. I have seen the two on The CJ3B Page and one is Hammerite bronze and the other is black. So what is the original? Mine has been painted too many times to tell."
Hank responded: "My '61 has a Harrison and it's original. It's black."
Oakes: "My '53 is gray with an original Willys sticker."
Wes Knettle:: "My 1960 3B stock heater is black. Could be early was gray and late was black."
Randy: "I have a NOS heater still in its original box and mine is the Hammerite bronze color."
Jim: "Just bought a '54 B from the original owner -- it has a top on it since new so interior is like new. The Harrison heater is a light silver in color with a slight hammertone to it. It has the sticker on it which is a slightly dull chrome with red Willys name in block letters."
Vern: "Try looking inside the heater case. You will probably find some original paint there, protected from the ravages of rust and careless repainting. So far it sounds like we've seen silver, bronze and black."
"The outside of the heater shown on my website was generally silvery in appearance, but had an overall faded look to it. When I opened up the case, the inside was definitely bronze. The new Hammerite Bronze I applied matched the inside paint nearly perfectly.
"Perhaps some of the silver heaters mentioned are bronze which have faded over the years. This is just a thought, so don't take it as fact based on one person's observation. This same heater had a 1956 date code and a Willys decal. I do not know the original source of the heater."
Buck Toenges: "Just got an original heater for my CJ-3B and need to know the placement on the firewall. Can anybody tell me where the holes go in the firewall? Measurements would come in handy."
Jim Sammons: "The holes are 10 inches up from the break (or bend) in the passenger side floor board. The outside hole is 2 inches from the outside (passenger side wall of the firewall). The holes are 3-1/2 inches apart and are 1 inch in diameter -- all measurements are from center of hole. As you know by looking at the heater, the holes are level with each other. Hope you can understand my description."
Bart: "On my heater there is just a sheet metal fitting attached to the right hand duct (centered on the heater bottom) which allows a round (roughly 2") hose to direct hot air to the windshield. It appears that the way mine is set up is that you cannot operate the defroster alone. When you heat the Jeep you defrost the windshield and heat both the passenger side and the driver side."
Note: The photo shows what appears to be an original defroster outlet, on the left duct on Bill Glasford's '57. See a photo of the entire heater (50K JPEG.)
Reed Cary: "Has anyone noticed the boss, just to the right and above the passenger side duct? I wondered about that boss when I had mine apart for restoration. I suspect that the original design included a lever (protruding from that boss) which controlled an internal flap-vent, allowing one to control (or close off) heat to the passenger duct (the square hole, on the bottom of the heater, to the right of the two driver-side directed ducts). Any other ideas? I made a rather crude snap-in aluminum door, to put in or take out, to send all the heat to the driver when no passenger was aboard."
Bart: "Regarding the coolant valve under the hood for the Harrison heater (or any heater system): mine apparently does not have a heater valve. This seems odd because isn't a valve the only way to fine-tune the amount of hot coolant going into the heater and thus controlling the amount of heat blowing out? Is the valve controlled from inside the cab and if so where is the valve control handle located? It doesn't seem to be located in the diagrams or pictures I've looked at. Is it turned on only when winter is approaching or is it turned on and off as heat is needed? Is it a means of contolling a measured amount of heat (hot coolant) to the heater core? This seems to make sense to me, but if so then where is the inside-cab valve control? I recall that my CJ-3A years ago did not have an in-line valve, or valve of any kind to control coolant flow in the heater. It had simply a one-speed motor switch and it worked just fine inside a Sears cab."
Reed: "As far as I know, all of the early heaters were controlled -- that is, as far as flow -- by a small valve attached to the head. Yes, I think there was a winter/summer thinking -- close the valve in summer, open in winter. These valves are still available, for example, through NAPA. (I picked one up off the shelf.)"
Note: The photo shows the heater valve on Larry Ford's mid-60's CJ-3B. The cable runs to a knob on the new-style fresh air heater and defroster (70K JPEG) introduced as an option in 1959.
Bart: "OK... the open valve at the rear of the engine takes the coolant while at it's hottest (having been heated by the hot engine) and sends it through the hose to the heater where it heats the heater core and loses some of its heat. The second hose takes the now spent coolant and sends it to the water pump where it is mixed with other coolant and sent to the radiator for further cooling. When the valve is closed (during the summer, hopefully) the hot coolant simply never reaches the heater core and therefore does not contribute more heat to an already overheated cab. It is interesting that the operation of the heater is not mentioned in the early factory service manual nor is it mentioned in the 1956 Owner's Manual that I have. I have driven lots of cars from the 40's and 50's and have never heard of a heater valve under the hood. That doesn't mean it wasn't there. Perhaps that is why some cars I've owned seemed to either be too hot most of the time or the heater didn't seem to work at all. Maybe I should have looked under the hood...."
A new, optional heater was introduced, apparently during the 1959 model year, with an exterior fresh air intake and a windshield defroster. The intake was through an approx. 4" hole in the right side of the body (40K JPEG), covered by a wire screen. If the new heater was not installed, the hole was covered by a round metal plate (20K JPEG). A photo of the late Janet Wathen Clark driving a brand new 1961 3B (100K JPEG) shows the plate painted black.
The hose for the defroster passed through an approx. 2 1/2" hole in the dash above the steering column, which was covered with a metal plug if the defroster was not installed. The February 1962 Jeep Universal Parts List lists it as the "Heater and Defroster, Fresh Air" including the defroster hose, windshield-mounted defroster manifold, and air inlet screen. We have narrowed down the introduction of the holes in the bodywork to between VIN's 5734851099 and 5734853243 in 1959.
The photo shows Tom Hill's 1959 CJ-3B.
Below are photos of a removed heater:
Thanks to all the contributors, including Wes Knettle for the photos of Louie Larson's '61 heater. -- Derek Redmond
Elsewhere on the web, there is detailed information on restoring a Harrison heater on Vernco.com and The CJ-3A Page.
See also an unusual heater found in Canada.
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