Heater fan motor not working 1994 class a HR

[Geocritter]

I’m having problems getting my heater fan motor to work in my 1994 Class A Holiday Rambler with a Ford F53 chassis. The following two pictures are of what I believe is the plug in connection for the heater motor.


I’m guessing this is the plug in for the heater fan motor. It has a 4 wires, a black wire (ground?), a yellow wire, a green wire and an orange wire. I’m guessing the black wire is ground and the other wires are for the various fan speeds.


Here’s the wire connection after I pulled it off. Sorry about the fuzzy photo but there’s not much to see.

Over a year ago I replaced the heater core in the unit. However, I’d also just completed a long tedious engine replacement project and it was mid-June in San Marcos TX. Because of the onset of the relentless Texas summer heat I didn’t finish the heater project. Now it’s over a year later, I’ve wandered north to Yorkville, IL outside of Chicago and am facing a 1,850 mile drive south to Arizona via Denver at the end of November. Unfortunately, the heater motor’s not working. I’m not worried about being cold myself, I pack a snowmobile suit, but I am worried about icy windows and would really like the defrost to work.

What I’ve done so far is I pulled the plug out (in photo 2) and with two alligator clips hooked to a 10amp 12 volt battery charger (one negative clip and one positive) I tried to get the fan motor to spin by attaching the negative clip to the black (what I assume is ground) connection that the wires in photo 2 plug in to and then touching the positive clip to the other connections one at a time. All I get is a light humming sound and the dial on the battery charger pegs at 10amps. Is my test even valid? I’m certain I remember the fan working in the past. At this point I’ll be happy if I can just run the fan straight off the battery with a two wires and a toggle switch.

Help me Obi wan you’re my only hope…

Steve

[subford]

No your test is not valid.
That plug is the resister pack for fan speeds and does not go to the motor.

Note that the high speed does not use that plug or the resisters.

If you have a Evans then this should be how it is wired:


OR

Mayb it is this one:

/

[Geocritter]

The top diagram looks correct. So somehow I have to figure out how to access the orange and black wires going to the blower motor so I can bypass everything else and hook up my toggle switch. Unlike many folks here personal comfort while relocating the Behemoth is not a huge priority of mine. After all it's not as if its my daily driver.


Steve

[charliej]

Try spinning the fan by hand with the power on. My AC fan just hummed, and once I got it going it works fine now. Maybe corrosion on the brushed.

[Geocritter]

The problem is the fan motor is inside a large plastic housing that's inside the front of my RV behind the grill. To get to it the entire front which includes grill and headlights has to come off. Not a huge job but I'd like to avoid it if possible. I wish it hadn't been so damned hot, humid and generally miserable that June when I installed the heater core after replacing the RV's engine.


As it is I'll keep tinkering until a stumble on to a solution. I have a pretty good brain when it comes to problem solving and thinking outside the box, I was simply hoping to shortcut some of that.


To those who responded, thank you for your help and suggestions.


Steve

[George Schweikle]

Assuming you determine the blower/fan is defective, you can access it without disassembling the front of the motorhome. The large fan motor housing is probably molded from "thermoplastic" material which can be re-melted (as opposed to "Thermoset" which can not be re-melted). The blower motor can be accessed by cutting (melting) a large hole in the housing using the flat blade that comes with every electric soldering iron. Once you have replaced the fan / blower, the access piece can be re-attached with good tape. Duct tape, or better yet HVAC aluminized tape. This scheme may be seen as crude by some , but it worked on my Safari Trek for heater core replacement and saved lots of almost impossible disassembly .

While there is a possibility the housing might be fiberglass, a light touch with a soldering iron will quickly indicate what material it is. If it melts, it's thermoplastic and the scheme listed above is possible if there is room to cut a sufficiently large hole.

Edit: Should have asked this first. Are you sure the blower/fan is inside the large housing?. On my Chevy chassis, the heater core was inside the housing on the outside of the firewall, but the blower/fan was on the passenger side; inside the motorhome and easily accessible.

Originally Posted by Geocritter

The problem is the fan motor is inside a large plastic housing that's inside the front of my RV behind the grill. To get to it the entire front which includes grill and headlights has to come off. Not a huge job but I'd like to avoid it if possible. I wish it hadn't been so damned hot, humid and generally miserable that June when I installed the heater core after replacing the RV's engine.


As it is I'll keep tinkering until a stumble on to a solution. I have a pretty good brain when it comes to problem solving and thinking outside the box, I was simply hoping to shortcut some of that.


To those who responded, thank you for your help and suggestions.


Steve

[subford]

It appears the the motor would be accessible from in side the RV:


The motor should look like this:


Does your controls look like this?

/

[98FPA]

On my 98 Pace Arrow, my problem was a relay. I have the Denso system so obviously could be a different setup. I could access my heater motor from inside the MH by removing the panel in front of the passenger seat. Here is a pic of my motor, it's the relay in upper right hand corner with the arrow shown on it.

[subford]

Originally Posted by 98FPA

On my 98 Pace Arrow, my problem was a relay. I have the Denso system so obviously could be a different setup. I could access my heater motor from inside the MH by removing the panel in front of the passenger seat. Here is a pic of my motor, it's the relay in upper right hand corner with the arrow shown on it.

The Denso system wiring diagram is the second (bottom) wiring diagram that I posted above.

[Geocritter]

Thanks to y'all for setting me on the right path. I thought for certain I remembered the heater blower being inside the outside plastic housing. Man was I wrong! Amazing what a year can do to your memory! The fan motor is inside the RV under the dash on the passenger side. Tomorrow I'm going to pull out the passenger seat (for easier access) and dig in and see what I can do to have a working defrost system in my RV.


Steve