That would be slick!

 

Update on the NAPA heater control rheostat... I hooked up one of my Porsche resistors (see post on p. 1 of this thread) in series with the NAPA switch. Perfect! High speed is reduced about 40% but it's still quite a blast, more than I'll likely need. I never ran it at full speed anyway, it was way too much. More important, the turn-down is really nice, goes all the way down to say 5% without the **** getting too hot.

The Porsche resistor is 12.5 ohms. I'm going to see where it runs with two in series and no NAPA control; if that works well I may convert to two-speed operation with a DPDT switch.

If you are interested in doing it this way, the Porsche 944 Turbo models came with two of these resistors mounted on an aluminum heat sink made to screw to the firewall with a safe space all around them. I got the turbo type for less than $15 off eBay. They are not really a "Porsche" part, 90% of a 944 is VW/Audi off-the-shelf Bosch crap, which keeps prices reasonable. There is one right now for $22 B-I-N.

Porsche 944 951 Radiator Fan Resistor Set - eBay (item 330419762079 end time Dec-27-10 10:39:26 PST)

 

That's great that it fixed the over heat on your switch.

Just to be sure, this is a heater that has already had the 6 volt motor replaced with a 12 volt motor, right.

There's another thread about reducers for 6 volt heater motors on 12 volt systems. Different ball of wax!

I'm also looking at the 12 volt Magic Aire Motor Woody found - I wonder if after installing that to get rid of the 6 volt motor your set up would help with the switches there too?

 

I have a Siemens 12v PM354. It could be that with the fan blades in my heater, it draws more current than the NAPA control can handle. If that is the case with the MagicAire replacement motor, then this could help there too.

 

Agreed! The pieces of the "Magic Aire" puzzle are geting fewer and the picture clearer. Excellent!

I know folks asking about 12 volt systems and 6 volt motors, who were reading here, and I just wanted to make sure that apples and oranges didn't get mixed!

 

hey guy's ..took my beast out last night and saw a glow under the dash and found the resister red orange ..so with your thread I now understand what to look at ..and check ...just to let you know you are appreciated for shareing the things you have learned ..mostly the hard way it seems...now how do I get more heat out this thing ..and how does the defrost work ..or does it ??I have flipped the leaver on the fan houseing and still scraping ice off the window...both sides...

 

I'm not familiar with the later units; is yours a fresh air heater? How hot is the air coming out of it? Could be the heater core is fouled, Ford had a lot of problems with that.

 

the air is luke-warm..not hot like my other trucks..the fan is running flat out I think it's still a 6 volt unit because of the multipul layers of paint..not sure about the fresh air part ..the valve on the supply side of the heater won't move the shaft is frozen in place..I am hopeing to replace it with a full flow fitting and install a new style controll valve it's damm cold here right now ..it's at minus 3 or somethin' snow on the ground ..

 

Here's the control valve I use, I got it at a swap meet but it's pretty universal:

Ford P/N C3UZ18495A
(Motorcraft YG133)

Fits: 1961/72 F100/1100. Some big trucks thru 1991.

Info courtesy NumberDummy

 

stuck my finger in the vent side of the heater houseing ..the flapper(?)for air controll is laying on the bottom of the houseing ..it's not connected to the leaver anymore so now I know why the defrost won't work .. and under 5 layers of paint it is a 6 volt fan..so should I replace it with stock....or look at maybe installing an air conditioning unit "vintage air" perhaps...what do you think?? comfort in summer or heat only?

 

I noticed this thread got resurrected. So I'll go ahead and give an update. I went ahead and installed the 6 volt version of the original switch Ross spoke about in the first post. So far so good. But I've not been brave enough to leave it turned way down very long at all. I usually just turn it on at full speed and then turn it off when it gets too warm. The 6 volt fan is not that strong which is good.

 

Here I go again resurrecting an old thread

So I have been seriously considering a couple few heater switches (mine came 1 speed, on/off toggle that says radio shack on it). And this thread helped me decide against 1 clearly. It's in the same vein as this thread so I'll add here and try to keep it all on the same topic.

Anyone who is using any of these switches please tell us what you think of them, how much they cut down the fan speed, etc - any details you can please. (These are ordered in my preference - so if #1 is terrible speak up and save me the headache if you would).

1)PWM mentioned above
rick - did you go ahead with this one or no?

MX033 - DC PWM Motor Speed Controller 15 Amp - Assembled & Tested

2)Wells SW8075
this one says 4 position, but only has 2 terminals (lead and load)... so I am wondering if they claim it is 3 speed...

Wells Manufacturing/12 Volts 3 Ohm four position universal blower and heater fan switch with two screw terminals (SW8075) | Blower/Heater Fan Switch | AutoZone.com

3) Ron Francis HS1

Ron Francis Wiring HS1 - Ron Francis Wiring Standard Heater Switches - Overview - SummitRacing.com

4) any other (LMC has a couple and one looks identical to the wells), mac's have the one that looks identical to this napa what started this thread..


For my application (converted to 12v, but still have 6v fan) I am open to either a 12v (mounted ahead of the resistor), or 6v (mounted after resistor).

My cage is great, my motor turns like a champ with either the 2a trickle charger or straight through the resistor no switch. Heater gets it hot very quickly, so I assume it would get very stuff if I try to go on/off only.

Thanks much guys

 

Both the Ron Francis and AZ switches have big resistors in the switch housing. I just don't like that. BobbyTNM posted here somewhere about using the GM-style wire resistor block that mounts in the side of the heater/A/C box so the heat is not in the switch and is force cooled; I like that, but I'd also like to know if the solid state ever worked out (and $$$).

 

Johnstone Supply used to have a three speed motor that you used with a 3pst switch. I believe thats what I'm using in my F100s.

 

Ross is correct, the two referenced switches have wirewound resistors mounted directly on them. The Wells switch probably has 2 resistors (it looks like 1 center-tapped resistor, same thing) to give 4 speeds:

• Low - 2 resistors in series
• Medium Low - 1 resistor
• Medium High - 2 resistors in parallel
• High - both resistors shunted.

There are only 2 terminals because all of the switching is done "on-board", so you need only a hot wire to one terminal & the motor lead to the other.

The Ron Francis switch has only 1 resistor as it is 2 position, Hi/Lo (resistor shunted/resistor in circuit).

The resistors look pretty small on both of these, which is not good when it comes to dissipating heat.

When the time comes for me to update my heater, I will use a speed control similar to, or the same as, your option 1. The only concern I have would be running the motor at VERY low speeds. There does not appear to be much (or any) filtering of the pulsed DC that is made available to the motor; the inductance of the motor itself is relied upon to smooth the pulses. This can result in cogging of the motor at very low speeds. I would remedy this by putting some resistance in series with the control potentiometer to limit the speed turndown.