heater fan force

[tahoe healey]

I am curious how much force should come from the heater fan. I seem to not get much either to the feet or wind screen. I am running neg ground by the PO and I don't know if the heater is ground sensitive. Should it have had the polarity reversed? It also appears that the defrost/foot-well director (on the big pipe) should be after the heater rather that between the fan and heater. I have never seen inside the heater so I don't know what goes on in there.

 

[glemon]

Ifc you don't feed the squirrel the output gets pretty week.

Most of these old heaters put out warm air but not much of it.

I read of a "fix" that as I recal involved running a higher amperage or guage wire to the blower from the fusebox--but others have said that if your system is working and wired properly this won't make any difference.

 

[mikespain]

If the car has been changed to negative earth from positive, then the fan will be running backwards,thrashing the air instead of pushing it ,try changing the wires COMING FROM the fan,ie what is now connected to the earth lead -connect to live wire and connect the wire that is connected the live wire to earth(ground)

 

[Keoke]

That is not necessary TH. The motor is noi polarity sensitive. Utilizing a higher amperage motor may help or move to the bottom of the hill.---Fwiw--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[Dave Russell]

Mike & Keoke could both be technically correct.
A lot of small motors were "series wound". The armature & field windings are internally connected in series. When the polarity applied to one winding is reversed, the polarity of the other is automatically reversed also, so the motor runs the same direction with either external connection. IE. The original Healey fan motors.

Most newer design fan motors, such as electric radiator fan motors, have a permanent magnet field instead of a field winding. These motors ARE polarity sensitive & will run either direction if the connections are reversed.

It's a little hard to know which specific type of motor is installed in an older car. Modern replacements for "old design" series wound motors have been known to have had the design converted to permanent magnet types. Permanent magnet motors are cheaper to build & possibly more reliable.

There are also brushless permanent magnet motors which replace the brushes with electronic switching. These more complex & expensive motors are not likely to be found on low cost applications.

Since it won't damage either type of motor to have it's connections reversed, it's easy to try both connections to see if a change gives the desired rotation direction.
D

 

[Johnny]

I've never been cold in a Healey. Who needs a fan?

 

[shorn]

When I purchased my Healey, there was very little air flow from the heater with or without the fan, although you could hear the fan motor run. Upon investigation, the incoming air duct to the fan motor was plugged with 13 pine or fir cones. Some industrious squirrel was using the duct for winter storage. True story.

 

[John Loftus]

I have never seen inside the heater so I don't know what goes on in there.

Hey T.H.,

I'll try to describe the Heater and Fresh Air routing on the 3000's. The heater fan sends pressurized air through the air duct to the right side of the heater box where there is a air flow control gate. With this open (control panel right knob pushed in), the air flows into the heater box where there is a heater core which is a small radiator circulating hot water. The amount of water flowing through the core is controlled by a valve which is adjusted by sliding the middle knob left to right (MIN to MAX). After the air is warmed by the heater core it goes to the outlets. Some air goes up through the small dia. ducts on the top of the heater box to the demister vents on the dash pad and some goes out the back of the heater box to travel left and right through the sheet metal plenum and out the screened openings and the hinged shutters that face down towards the foot wells.

The fresh air system is controlled with the left control knob (pulled out is fully open). This opens the air flow control gate at the front of the left air duct and lets fresh air flow into the plenum where it can flow out of the screened opening and hinged shutters into the footwells.

So if you want max heat you keep both knobs pushed in (fresh air closed and heat blower air open). If you want more air to the demisters you close the foot well shutters.

That said, the original heater blower motor is not very strong compared to modern cars.

Cheers,
John

 

[tahoe healey]

Thanks all. I'll try reversing the ground. All the ducts are new (5-6 years). I'm more concerned with the defroster. But doesn't the fitting of the deflector seem strange prior to the heater?
Thanks Mr. K but I think I will stay up here when I hear the summer temps in the flat lands of California. With global warming and all, you guys ain't seen nothing yet. I remember the asphalt melting under my shoes 15 years ago when 100 degree temps were considered hot.

 

[John Loftus]

But doesn't the fitting of the deflector seem strange prior to the heater?

What are you calling a deflector?

 

[tahoe healey]

The push/pull dash knob operating the cable on the right. It moves a contraption in the big duct just before the heater unit.

 

[John Loftus]

o.k. that's what I referred to as the 'air flow control gate' above or I think the official name is the 'air valve'. Since the air can flow in multiple directions as it exits the heater box (to the demisters and to the plenum) it was probably the easiest/cheapist/simplist way to do it. If you are having problems getting air to the demisters you can close the hinged shutters in the foot wells but you may have leaks from the heater box to the demisters. There are rubber elbows that fit into holes in the top of the heater box which can leak if they are old. Then there are paper ducts that go to the demister area that could be leaking. Then there is another set of rubber elbows that connect the paper duct to the bottom of the demister area and are held in place with a metal plate. Finally, any gaps between the super structure and the underside of the shroud needs to be sealed around the edges or you won't get much flow out the demisters. Unfortunately, this is not easy to seal in-situ but should be addressed when the shroud is replaced during a restoration.

Cheers,
John

p.s. the Moss catalog has a good exploded view showing the parts. You may be able to reach up and feel if there are any major leaks in the demister hoses during operation. Might be tougher with the BJ8 center console in the way?

 

[Keoke]

Hi John, TH is probably calling the control flap up under the dash which controlls the flow of air to the heater box a "Deflector"--Keoke-?