The Operation and Maintenance of the Heater
for a
Non Air-conditioned 1962-1965 Mopar B-Body.
Plus, Additional Note on the Regulator on a Mopar Heater
Heater Article by Kevin Merkley | Mopar Regulator Advice by Butch Edison
Operation and Maintenance of the Mopar Heater
It is surprising that since almost all of the B-Body cars produced between 1962 and 1965 had heaters that there is very little information about the "Black Box" that exists under our instrument panels.
I hope to shed some light on the mystery that may surround the heater assembly by identifying the parts, what they do and how the heater operates when we push the buttons.
The heater is a box that contains the following major components.
Heater core
The heater core is like a small radiator that uses the hot water from the engine to transfer heat to the vehicle by passing air through the heater core.
Resistor block
The resistor block is a small plate attached to the side of the heater box that is connected to the fan switch. When you change fan speeds, the switch directs the power through one of the resistors and as such reduces the power available to the fan motor. If you have power to the fan motor for some speeds but not all, there may be a problem with the resistor block. If all the resistors are damaged, there will only be operation of the fan at high speed.
Heater water valve with thermostatic coil
The heater water valve allows water into the heater core by opening when the temperature lever is moved towards "warm". The cable attached to the temperature lever pulls the water valve more open or more closed depending on the movement of the lever. This gives the operator control of the amount of heat delivered by the heater.
There is also a temperature sensor on the heater valve that is a long coil of copper that is located under the heater core inside the heater box. This coil allows the water valve to automatically regulate the amount of water entering the heater core to maintain the desired temperature as set by the temperature lever.
Defrost/Heat damper
The defrost/heat damper is located inside the heater box below and to the front of the heater box. Its purpose is to direct the air after going through the heater core to either the defrost ducts or to the floor area of the vehicle. The damper does not fully block the airflow at any time and will direct most of the air. As indicated in the FSM (factory service manual) and the owners manual even if the damper is moved for either defrost or heat, there is some leakage around it so that there is always some air directed at the windshield or the floor.
The defrost/heat damper is actuated by a vacuum motor that is attached to the driver’s side of the heater box closest to the rear of the vehicle (front of the heater for this discussion). The hoses are connected as follows: Hose 1 (B/W): diaphragm side, Hose 3 (B/R) plunger side.
Cool/Heat damper
The cool/heat damper is located under the heater box at the front of the vehicle (rear of the heater box in this discussion). The damper rotates to either direct heated air to the floor of the vehicle or to rotate counter clockwise (when viewed from the driver’s side) and allow the outdoor air to bypass the heater core and go directly to the passenger compartment.
There are foam seals on the damper to control the amount of leakage when in either position.
The cool/heat damper is actuated by a vacuum motor that is attached to the driver’s side of the heater box closest to the front of the vehicle (rear of the heater for this discussion). The hoses are connected as follows: Hose 7 (B/W): diaphragm side, Hose 5 (B/R) plunger side.
Other components
In addition to the actual black box are the fan and the outdoor air damper, which is also controlled by a vacuum motor.
On the back of the heater control are two wires. A purple wire that goes to the fan switch and a black wire that goes to the fuse panel. The black wire connects to the terminal above the nipples numbers 1-3. The purple wire connects to the terminal above nipples 4-7.
If you remove the hose connection from the back of the heater control use extreme caution. The plastic nipples are very brittle and can easily break causing the heater to malfunction and a vacuum leak.
Below represents the plug for the back of the heater control.
The nipples are numbered for reference in the document and the colour of the hoses is indicated for convenience.
 |
|
4 B/W |
| 1 B/W |
|
|
5 B/R |
| 2 B (engine) |
|
|
6 B/R |
| 3 B/R |
|
|
7 B/W |
|
Heater Control Hose Description
| Hose Number |
Colour |
Description |
| 1. |
B/W |
Diaphragm Side defrost/heat damper |
| 2. |
Black |
Intake Manifold |
| 3. |
B/R |
Plunger Side defrost/heat damper |
| 4. |
B/W |
Diaphragm Side outdoor air damper |
| 5. |
B/R |
Plunger Side cool/heat damper |
| 6. |
B/R |
Plunger Side outdoor air damper |
| 7. |
B/W |
Diaphragm Side cool/heat damper |
Sequence of Operation
The sequence described explains what is happening in the heater and also allows you to confirm the operation of the vacuum motors by watching the movement of the plungers.
When any button is pressed (except for "OFF") the outdoor air damper, located above the passenger’s feet, opens to allow air into the vehicle. There are no other vents in the vehicle to allow "fresh air" into the car, except the windows.
"OFF"
The "outdoor air" plunger = in. (Air is shut out of the vehicle).
"HEAT"
The "outdoor air" plunger = out. (Air is allowed into the vehicle).
The "cool/heat" plunger = in. (Air is directed through the heater core).
The "defrost/heat" plunger = out. (Air is directed under the heater core and towards the rear of the heater to be sent to the floor of the vehicle).
"DEFROST"
The "outdoor air" plunger = out. (Air is allowed into the vehicle).
The "cool/heat" plunger = in. (Air is directed through the heater core).
The "defrost/heat" plunger = in. (Air is directed into the defrost chamber of the heater box to the defrost outlets).
"COOL"
The "outdoor air" plunger = out. (Air is allowed into the vehicle).
The "cool/heat" plunger = out. (Air bypasses the heater core and goes directly to the floor of the vehicle). This is the only time that the bottom vent on the heater box rotates. The vent will rotate to move the vents to a horizontal position.
Article by Kevin Merkley posted January 13, 2004
Mopar Heater Regulator Advice
by
Butch Edison
Update: Butch Edison provides additional helpful information.
Several years ago, I rebuilt the heater in my 1964 Plymouth with some great help from Kevin Merkley up in Thunder Bay, Canada. I used a new core and a rebuilt regulator. Anyway, the heater has never produced heat like my original car did back in 1964. That thing would literally cook you out. I'd looked under the dash more than once and could see the regulator on the heater opening and closing as I worked the heat control lever, so figured it was okay (lesson to be learned here!)
I'd like to drive my car more in the fall, winter, and spring so determined I had to figure this out.I mean, how hard could it be? Well, I found out :)
First, I drained the radiator, unhooked both hoses from the heater and pushed compressed air through the unit. Worked okay, but that's not a true flow test, so....
Next, I hooked up both hoses back to the heater. I unhooked the block-end heater hose that returns coolant to the motor from the heater core, and stuck it in the radiator fill neck. I put a stopper in the discharge port of the block so nothing could get out of the motor. Refilled the radiator and started the car with the heater control valve lever on the dash all the way open (down in my case). Well, there was only a trickle of coolant coming from the heater back to the motor.
I "assumed" something was wrong with the regulator or the core. You can't back flush these units as that action tries to close the regulator. It shouldn't have needed it anyway, but felt I was running out of options, so....you know it's coming, took the heater unit out of the car completely. I couldn't find anything wrong! I even took the unit to Jeff Carter at JC Automotive in Lynwood, WA. He tested it and said all was good. He told me to carefully check the throw on the regulator once it was back in the car, to be sure it was completely open.
Another several hours reinstalling the heater, hooking it all up, fill the radiator and start the car. THIS TIME, I did not hook up the cable that runs from the dash lever to the regulator under the dash. I mocked it up and held the regulator cable where it would rest when hooked up to the regulator bracket and GUESS WHAT? The wire that slides back and forth within the cable would not open the regulator fully. It was about 3/4" short. It would barely open the valve. I manually opened the regulator valve to full flow and the heater started working correctly immediately.
So, what was the issue? The problem was that the remanufactured regulator I used was configured differently than the one that came out of the car. The remanufactured unit had a "stop" on it, a perpendicular metal tab that stopped the cable while allowing the controller wire to move back and forth. I broke off the little piece of pot metal, manually opened the regulator valve on the heater completely, then clipped the cable to the regulator. The heater now works PERFECTLY!
I should have taken pictures along the way, but did not, so this little missive is just meant to pop on a mental light bulb if you decide to replace the regulator on your Mopar heater. Check the throw on the regulator FIRST, not LAST! It might save you hours and hours of frustration.
Advice by Butch Edison posted 12-31-2016
Contact information: krmerkley at yahoo.com | waedison at comcast.net