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#1062545 - 06/27/19 03:29 PM Blower motor speed  
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SSLance Offline
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So now that my car is much better suited for being daily driven, I need to get my AC up to speed. The compressor works great but the blower motor only work on HIGH and is at best at medium speed there.

What do I chase first to try to get multiple speeds from the blower motor and hopefully much more airflow when on high?

The vacuum operated doors and all seem to be operating as they should, all functions of the heater controls work. The only issue is the blower motor itself.


Lance
1985 Monte Carlo SS Street Car
#1062547 - 06/27/19 03:56 PM Re: Blower motor speed [Re: SSLance]  
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Travis Jones Offline
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Lance,

Have you checked the resistance on your blower motor control board?

https://www.amazon.com/Dorman-973-4...;qid=1561650866&s=gateway&sr=8-1

These wear out over time, typically the lower speeds go out and then only high works. It's mounted high on the AC/Heater box.

Might toss in a new blower motor and fan while you're in there.
https://www.amazon.com/ACDelco-15-8...p;vehicleName=1986+Chevrolet+Monte+Carlo


86 SS 6.0L LQ4, TBSS GEN IV intake, 92mm TB, 30lb injectors, Summit Stage 3 NA Cam, Stainless long tube headers, Stainless 3in exhaust, Microsquirt ECU, FABbot AR5 5-speed, Torsen LSD, QA1 Lvl 3 Suspension Kit, UMI Front & Rear Braces. Check out my build blog on Summit Racing's OnAll Cylinders https://www.onallcylinders.com/author/travis-jones/
#1062548 - 06/27/19 04:01 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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I haven't done anything to chase it down yet, but that looks like a good place to start.

Thanks


Lance
1985 Monte Carlo SS Street Car
#1062560 - 06/28/19 01:20 AM Re: Blower motor speed [Re: SSLance]  
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86ttop Offline
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The blower resister and just an FYI, when I replaced my heater core, I also replaced the blower motor and cleaned out the box the evap/heater core are in. You might be able to do the same just by taking the blower motor out. Have you checked this possible problem too: www.montecarloss.com/SS_FAQ_16.html#4 Good luck!


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#1062654 - 07/07/19 12:03 AM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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I need a favor please... Can someone with a working blower fan check to see how the operating voltage of the battery changes when the blower fan is switched on?

For example, on my car currently it'll be idling at 14,1v and turning the fan on high drops it down to 13.1v. That is way more of a drop than my dual engine cooling fans create...


Lance
1985 Monte Carlo SS Street Car
#1062655 - 07/07/19 03:05 AM Re: Blower motor speed [Re: SSLance]  
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mmc427ss Offline
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As noted in one of your previous voltage posts 1 vdc drop with just the blower motor running is way to much. The 86 is apart right now so can't help you with voltage readings while running. Maybe Weds.

Make sure the ground to the blower is good, this would effect speed, slower, may drop voltage. Check the Purple 12+ connection to the motor. Could give you an ohm reading for the motor but not till Sun when I see the car again. Measure blower motor housing ground to the motor + input. This would tell you if the armature or brushes are OK. That could cause excessive amps, drop voltage. Have replaced many blower motors, bushes gone, armature burned, bushings junk. Ohms reading a good indicator brushes/armature/commutator. The blower motor in my car has twice the mileage as yours, still original, as is the resistor, and relay, but the wiring/connection have all been "serviced".
Bearing (bushings) in the motor dry out, wear out, can cause high current draw, voltage drop.

Things to check with a VOM.
Blower resistor ohm readings. Wires disconnected,
A (Brown wire connect there) to C (Tan) 1.5 ohm
C (Tan) to D (Lite Blue) .7 + or_-. 5 ohm
D (Lite blue) to B (Dark blue) .2 + or - 1 ohm

Blower relay terminals:
A (Purple) runs to the blower motor 12+
B (BLK) is ground for the relay coil
C (Dark blue) is coming from the resistor's B terminal and the output of the resister dependent of the blower switch speed, Lo, M1, M2. On this wire is where you see three different voltages to the blower.
D (Red) this voltage is feed directly off a Fusible link, hot all the time.
E (Brown) this is the feed directly to the relay from the High selection on the switch, It activated the coil in the relay which puts power from D over to the A terminal. When a slow speed is selected no power comes from switch to the coil in the relay. The contacts in the coil now are closed, C connected to A, so the power to the motor is provided through the resistor. Four speeds is the result of how this old circuit works.

E (brown) to B (black) should show a resistance, but can't find ohm reading, guess about 10 ohm. This is the coil for the relay.


Yes maybe the blower motor is tired. The resistor can be visually checked, but checking ohms can determine good. Saw on Rock they had a close out of the Delco resistors, bought one to have if I need it. Relay can go bad, just a coil that is activated only on High, contacts can get used up but would think that would show up most of the times when you can't get high speed to work.

Check your fusible links.
Still think your voltage drop problem is an alt issue.
Bob

#1062656 - 07/07/19 05:05 PM Re: Blower motor speed [Re: SSLance]  
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AkronAero Offline
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Bob - I forgot about the resistors - I changed them out when we got the car - only worked on high speed. So thanks again.

Lance - I don't have digital VOM but looking at my analogue Radio Shack Micronta from 45 years ago (used it to build my Heathkit receiver... hahaha):
I see it resting on 13 volts whether I have the blower/fan or the dual radiator fans on or off as measured across the battery or from the alternator to ground.
Alternator is 140 Amp single wire.
My new Speedhut dash voltage shows about 1 volt higher (probably more correct). I will need to look into this so thanks.
If I turn on the headlights on high at idle the voltage drops about 1 volt.

Anything else I can check?

Gordon

#1062658 - 07/07/19 08:34 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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Thanks Gordon, that's perfect. New resistor will be here Tuesday.


Lance
1985 Monte Carlo SS Street Car
#1062662 - 07/08/19 12:20 AM Re: Blower motor speed [Re: SSLance]  
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mmc427ss Offline
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Checked blower motor today, got 1.2 ohms between ground and spade + terminal on motor.
Bob

#1063056 - 08/08/19 07:55 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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Okay, step 3... Who can help diagnose if this is the issue?

[Linked Image]

I do have a DOM but I am not an expert at running it. I know how to check for volts with it but anything past that will require detailed instructions... laugh

[Linked Image]

Looking at the switch, it is NOT what I expected it to be.

[Linked Image]

[Linked Image]

[Linked Image]

It looks like to me this switch just tells the 12v which path to take, does that sound correct? If it works on high, then one has to assume that power is getting to the switch. I just have to figure out why it is not going out when the switch is in the lower speed positions. I'm tempted to take it apart and clean it up...there was some oily substance on several of the slide connectors but I'm having a hard time believing that would prevent current from flowing through where it was supposed to go.

Any ideas?


Lance
1985 Monte Carlo SS Street Car
#1063057 - 08/08/19 08:03 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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So on the connector, the bottom wire (brown) has 10.8v on it when grounded to shifter and when grounded to the 2nd from bottom (orange).

The top two wires don't do anything, act as a ground, turn blower on, or have any power on them.

[Linked Image]


Lance
1985 Monte Carlo SS Street Car
#1063058 - 08/08/19 08:16 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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Checking continuity of the switch reveals this.

[Linked Image]

No continuity between any tabs in Low
Continuity between top and bottom tab in Med Low
Continuity between top and 2nd from top tab in Med High
Continuity between top and 3rd from top tab in High

Blower fan only comes on when switch is on High


Lance
1985 Monte Carlo SS Street Car
#1063059 - 08/08/19 08:18 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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That tells me the switch is working properly, correct?


Lance
1985 Monte Carlo SS Street Car
#1063060 - 08/08/19 08:26 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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Peoria, AZ
Sorry I'm posting blow by blow but it's the only way I can remember... laugh

So now I'm at the blower motor itself. Switch installed, key on, switch on HIGH...blower motor runs without the resistor board connector even being plugged in. One of the 4 tabs on connector has voltage on it.

When I plug the connector into the brand new resistor board, nothing changes. No matter what I do, blower motor won't run with switch in any other position other than HIGH. On Med High, two of the tabs on connector have voltage on them though. Didnt' check but I'm assuming in other positions other tabs will have power.


Lance
1985 Monte Carlo SS Street Car
#1063091 - 08/10/19 09:51 PM Re: Blower motor speed [Re: SSLance]  
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SSLance Offline
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So, with a big assist from Bob sending me the wire diagram and test procedures...I narrowed it down to the blower relay. $15 later and a few screws...BAM 4 speeds from the fan once again and the draw is now only a few tenths of a volt when on high, two birds...one stone.


Lance
1985 Monte Carlo SS Street Car
#1063094 - 08/11/19 12:59 AM Re: Blower motor speed [Re: SSLance]  
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mmc427ss Offline
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BINGO. Will be nice to crank that A/C on, windows up all the while laying on the throttle in the sunny SW.

Took my grandson for a long drive last evening in the 86. Amazing how the kids don't mind the cold. The almost original R12 system will freeze your toes off.
Happy motoring.
Bob

#1063099 - 08/11/19 01:38 AM Re: Blower motor speed [Re: SSLance]  
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86ttop Offline
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thumbs Bob and Lance!!


Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs

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