Running power to heater motor - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
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post #1 of 9 (permalink) Old Mar 22nd, 01, 05:45 PM Thread Starter
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Joe
 
Join Date: Jan 2001
Location: Benicia CA
Posts: 1,294
Question

Ok guys, don't laugh at me!
My 69 was originally an AC car. The AC was removed, the suitcase cut down and fibreglassed over to make a flat surface to mount the ignition box and coil on. The guy did a pretty good job. I thought it was original at first.

The heater and defroster functions work well when the car is moving, but the fan motor has no wiring to it. The AC harness has been cut off under the dash.
The AC switches are intact behind the heater control panel on the dash. I thought the AC resistor was mounted on top of the air box, but was mistaken.

I have jumpered the heater motor and it works fine. I'd like to get the heater motor working from the heater switch.
I am comfortable making a harness, using the wiring diagram as a guide, but have a few questions.

1) Can I use a non AC resistor and wire the fan as a 3 speed? I realize I would lose a position on the switch, but these seem to be cheap and available. I would bypass the "Lo Blo" switch completely.

2) Where is the fan relay located? (It may still be there somewhere)

3) The power to the relay comes from the horn relay with a fusible link. I don't have a horn, so am unsure where to look for this relay. (I'll be doing this too)

4) There are two terminals on the motor; one long, one short. I think the long one is positive. Is this correct?

5) Can I run the ground from the motor to the frame or firewall, or is it grounded back through the switch, like the wiper motor switch? The wiring diagram seems to have it grounded to the dash.

I plan on using the correct colors and gauge for the harness.
Am I missing anything?

I know this is a long post, sorry. I just want to wire it correctly, even though it sounds funky.

Thanks in advance for your help and patience,
Joe

------------------
69 396 w/SS Trim, B&M TH400, 3.55 12 Bolt Posi, Blue w/White Z28 Stripes, Chrome Rally Wheels
[email protected]
69 Pics http://albums.photopoint.com/j/Album...559&a=11674961

[This message has been edited by Joe G (edited 03-22-2001).]

[This message has been edited by Joe G (edited 03-22-2001).]
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post #2 of 9 (permalink) Old Mar 23rd, 01, 05:24 PM
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Mark
 
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Location: Shrewsbury, MA, USA
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1) Non AC resistor is a three terminal resistor assembly mounted on the top of a non A/C inner heater duct assembly. It controls the two lowest speeds on a non A/C system, and the high speed setting is hardwired through the non A/C fan switch itself. You should be able to wire up a harness without too much trouble. You do have to be careful where you mount the resistor though. It has to be mounted in an area of the ductwork that can not have the air flow shut off to it, or the resistor coils will melt. An A/C inner box has two air flow paths in it, one that bypasses the heater core and sends the air up into the upper duct directly (A/C mode), and one the sends air in a loop through the heater core before distibuting it to the upper duct (heat mode). Best place is directly behind the air distribution assembly (the part that connects the lower plenum to the upper plenum with the two circular louvers in it). There are a ton of levers and damper controls in this area so you need to be careful where it goes.

You could always put it in the outer section of ductwork in the engine compartment. That would probably simplify finding a location with constant air flow.

2) The fan relay was located on the top of the A/C suitcase in the engine compartment just in front of the original blower motor resistor. If the resistor is gone, then so is the relay.

3) The horn relay is on the radiator core support, on the drivers side about 4 inches away from the radiator and 6" down from the top of the core support. It is also where the alternator is tied into the cars electrical system. The power to the relay came from the fan speed switch. Placing the switch in High sent 12 V to the relay which energized the coil. The contacts associated with the relay are connected on one side to the fan motor, and the other side is connected to the horn relay through a 25 amp inline fuse holder.

4) One terminal is power from either the blower motor resistor or fan relay, the other is ground. The one with the circular plastic insulator is the positive one, the one rivited right to the metal flange is the ground. A ground is needed because the A/C engine compartment duct is fiberglass, a non A/C one is metal so the motor is grounded through the duct itself.

5) Ground is ground, you can attach the ground wire anywhere you want. The original ground is right next to the big grommet in the firewall to the right of the suitcase that had all the A/C wiring in it. It is a screw with a serrated ring tongue terminal under it at about 5 oclock relative to the grommet hole.


------------------
Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11
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post #3 of 9 (permalink) Old Mar 23rd, 01, 06:39 PM Thread Starter
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Joe
 
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Location: Benicia CA
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Cool

Hey Mark, you found me again!
I found the horn relay and the lead with the in-line fuse. It's still there so some of my work is done.

I appreciate the detailed answer; it will make wiring this thing a lot easier.

It's great to have knowledgeable people like yourself willing to give advice.
Thanks again
Joe

------------------
69 396 w/SS Trim, B&M TH400, 3.55 12 Bolt Posi, Blue w/White Z28 Stripes, Chrome Rally Wheels
[email protected]
69 Pics http://albums.photopoint.com/j/Album...559&a=11674961
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post #4 of 9 (permalink) Old Mar 31st, 01, 08:14 AM Thread Starter
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Joe
 
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Location: Benicia CA
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Question

Another question.

The wiring diagrams show that cars W/O Ac did not have a relay for the heater. Since I have a non AC resistor, can I just wire the switch, relay and motor as if it were non-AC? Turns out the wiring form the horn relay is gone after all.

It looks like the relay was to activate the AC system as well as the heater motor.
I'm thinking I really don't need a relay in the system?
Thanks for the help.

Joe

------------------
69 396 w/SS Trim, B&M TH400, 3.55 12 Bolt Posi, Blue w/White Z28 Stripes, Chrome Rally Wheels
[email protected]
69 Pics http://albums.photopoint.com/j/Album...559&a=11674961
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post #5 of 9 (permalink) Old Apr 4th, 01, 11:37 PM Thread Starter
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Joe
 
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Cool

Any suggestions?
Joe

------------------
69 396 w/SS Trim, B&M TH400, 3.55 12 Bolt Posi, Blue w/White Z28 Stripes, Chrome Rally Wheels
[email protected]
69 Pics http://albums.photopoint.com/j/Album...559&a=11674961
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post #6 of 9 (permalink) Old Apr 5th, 01, 07:40 AM
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Mark
 
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The A/C blower motor is diffeent than the non A/C motor. I believe it is wound differently and operates at a higher speed than a non A/C blower, and thus draws more current. The relay on the suitcase only operates the fan motor, and originally provided power to the fan thru a 25 amp fuse in an inline fuse holder on the firewall. The power to pick up the clutch on the compressor comes from under the dash with the power to pickup the coil in the relay, and the power for the three lower fan speed.

Don't think you can run the A/C fan in high speed directly through the fan switch. It will probably blow the Fuse for the Heater circuit.

You may be able to find a relay that is rated for 20-25 amps (like a headlight or fog light relay) and use it like the original installation, and run the three lower speeds thru the switch on the dash.


------------------
Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11
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post #7 of 9 (permalink) Old Apr 6th, 01, 12:05 AM Thread Starter
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Joe
 
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Cool

Thanks for the reply, Mark

I'll get a relay. I'll be using a non AC resistor (hope it works) so will only have 3 speeds total. I'll be mounting the resistor in the air supply to the heater/defroster box (if that is the right term).

I have run the heater motor direct through the switch and let it run for ~ 5 minutes and none of the wires felt warm or anything. That's why I was thinking I didn't really need the relay.

I used 12 gauge wire which is larger than what is used on the non AC motors. Is this large enough for the AC motor? The assembly manual diagram shows a 10 to the relay and motor but it also send some power to other things (it looks like).

Thanks again. I appreciate your advice.
Joe

------------------
69 396 w/SS Trim, B&M TH400, 3.55 12 Bolt Posi, Blue w/White Z28 Stripes, Chrome Rally Wheels
[email protected]
69 Pics http://albums.photopoint.com/j/Album...559&a=11674961
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post #8 of 9 (permalink) Old Apr 6th, 01, 02:26 AM
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Mark
 
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12 gauge wire is rated for 20 amps, 10 gauge would be rated for 25 amps. As long as you install a fuse with the appropriate rating you won't have a problem. Just remember that the wire on the battery side of the fuse also has to be the same size all the way back to the horn relay. Don't stick a 10 gauge wire and 25 amp fuse off of a 16 gauge feeder wire, or you'll smoke the 16 gauge wire. Thats why GM originally fed it directly off of the horn relay instead of bringing it out of the heater circuit under the dash. You can get a replacement harness that has the fuse holder in it from any of the Camaro parts vendors for about $9, or go down to Walmart and buy an inline fuse holder for about $2 and a roll of number 10 wire for $3.

I doubt that the contacts in the switch in the dash are rated for the full speed current draw of the fan. They will eventually get pits in them from the arc formed as they open and will either fail open (no power thru switch) of weld themselves together. Another reason for the relay.




------------------
Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11
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post #9 of 9 (permalink) Old Apr 7th, 01, 12:26 AM Thread Starter
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Joe
 
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Location: Benicia CA
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Talking

Thanks Mark.
That all makes sense. I thought I could save a little work, but as usual, not.
Looks like a new relay, a bit of #10 wire, and some more time on my head under the dash is in order.

Wish I hadn't done such a "professional" job of running the #12 wire to the motor; harness tape, clips, grommet in the firewall, etc. Guess I should get the advice, then do the work, not the other way around!

Got the non AC resitor today (along with the new radiator, fan, shroud, etc) so I'm spending the weekend in the garage!
May be back on the road Sunday.

Thanks again for your advice
Joe

------------------
69 396 w/SS Trim, B&M TH400, 3.55 12 Bolt Posi, Blue w/White Z28 Stripes, Chrome Rally Wheels
[email protected]
69 Pics http://albums.photopoint.com/j/Album...559&a=11674961
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