What purpose does it serve and can it be side-stepped?

[Ken]

Everyone knows what this is, right?

Well, if you don't know, it's the thing that controls your blower speed in your heating/air conditioning system. It usually resides on top of the blower housing. Each of the coil-like devices controls the different fan speeds, i.e., low/medium/high, although exactly how I couldn't tell you.

Which is what brings me to the subject of this post: How does the thing work, and is it absolutely necessary for the blower fan to operate properly? The reason I ask is that I have to modify the set-up I have installed because we forgot to take this piece into consideration when modifying the old housing. (I eliminated the air conditioning in my Corvette.) Any tips will be appreciated.

 

[KOPBET]

Ken,

Reference the diagram below. The three coils you see make up a series resistor with seperate taps for each fan speed except "high". For low speed, all of the resistors are in series causing maximum resistance and highest voltage drop leading to the fan motor. Each higher speed selection selects a tap with less resistance, hence smaller voltage drop before the fan and more voltage to the fan motor. The high speed switch selection energizes the fan relay (and bypasses the resistors you have before you) which provides 12v directly to the fan motor. If you don't put the assy. back in, the lower speeds will not work but "high" will. You could possibly fashion something to take the place of the resistor coils. Clear as mud now?

 

[Ken]

That certainly helps. Thanks!

_ken

 

[ErnieN85]

Ken, there is another thing to be aware of the air flow cools the resistors with out being in the air stream they would probably burn out quickly.

 

[Ken]

Thanks Ernie, I'm aware of that.

 

[SPANISHVETTS]

Ken,
You could control the fan speed electronically with an IC. The IC would produce less heat than the resistors and therefore not need to be cooled. ICs are also cheep!!

How many fan speeds do you need and how much amperage does the fan draw? I will be happy to look up the part #s you need and sketch a wiring diagram.

 

[Ken]

My main concern Spanish, is that I have a fan for the windshield (defroster). Not that I have ice to worry about here in SoCal, but it do get fogged-up. :L

I haven't a clue as to what the blower motor draws in the way of amperage.

_ken

 

[Grizzly]

How much current?

Check the fuse box................
That will get you close. If you don't need AC then you just want to clear the windshield quickly, right? A simple on/off for high speed.

 

[Ken]

A/C?? This car ain't got no stinking A/C!

 

[SPANISHVETTS]

Here is a link to an IC regulator that will handle 10 amps. It is also available in a 20 amp version. http://www.mskennedy.com/pdf/5012rh.pdf Almost any electronic supply house will have this in stock. You would be better off getting Vigman, Jeff or anybody else who has an account with a wholesaler to pick it up for you. Electronic parts are marked up 60% or try to get an equivalent part from Radio Shack.

Do you still have the factory heater control panel? If so the original switch can be used, if not you could have a constantly variable fan speed.

I am suffering from an arthritis attack today. 400 Dutch sailors came to the track last night…the only problem was that most of my help took the day off which forced me to hand start the karts more or less 400 times. I am so full of anti inflammatories and pain pills that this post might be a little fuzzy but I think it is correct for the most part.

 

[KOPBET]

A simple on/off for high speed.

That he already has. The fan relay handles this and is seperate from the resistors above.

 

[Grizzly]

That he already has. The fan relay handles this and is seperate from the resistors above.

I doubt it, a relay still needs a switch.

By the way Ken I wouldn't like stinking AC either. Probably take it to Coit and have the ducts cleaned out.

 

[Moonunit 451]

That he already has. The fan relay handles this and is seperate from the resistors above.

Ok, a little variation on the theme here. When I put my car back together the only thing that didn't work is the high speed fan and I want my stinkin' air conditioningand I want it to blow COLD and HARD. Is this the switch or the relay? Where is the relay :confused

 

[ErnieN85]

It's the relay it's either bad or simply unpluged. the relay is controled by the high switch position contact and needs to be in place for the slower speeds to work so it's probably pluged in the relay itself is on a bracket just under the blower motor in the right fender take a look under there you'll see it. check for voltage on the orange wire with the car on and the blower switch on high. if there is voltage on that wir e it's trying to turn on the relay. and time for a new relay if not it's the switch or wire from the switch to the relay although it could be just the relay socket dirty!

 

[KOPBET]

I doubt it, a relay still needs a switch.
.

Uhh, isn't the fan switch still in the dash?

 

[Moonunit 451]

Earnie,

Thanks a lot. It would seem there is a small amount of voltage going through there so I guess I'll try a new relay. Do you know if that's available aftermarket and what years the part applies to by chance? It's all pretty clean. I through a little more dielectric gunk in there, even tried a little of the bigger

routine to no avail

 

[ErnieN85]

it should be available almost any where I bought my last one (for my truck) at NAPA

 

[Moonunit 451]

Thanks Eriie, got destracted driving.

 

[Moonunit 451]

Relay didn't work, any other suggestions :confused

 

[ErnieN85]

Well check the power to the relay ther is a big wire which goes to the main power feed through a fusible link from the relay. that feeds the blower on high then the relay triger from the switch in the dash and a ground to the frame? all in all four wires one to the blower, one to the battery, one to groung and one to the switch use a test light to verify them a meter will show voltage wit a bad connection some times but a bulb won't light. so first check fot he power to the relay as its hot all the time then make sure the ground isn't off, it might be a bad plug (relay socket)