Ok, today I went and pick up a new blower motor because my other one was shot. To make a long story short I put it in and it didn't work. So I went back under the hood and wiggled the wires to see if that would fix it. It didn't so I thought maybe my switch is bad. So I got a volt meter and there was around 7.8 volts at the first three positions and nothing at the 4th (fastest) position. My question is, what should the volts be at and what determines the speed of the motor. I tried to figure this out my self and I went to my dads truck to see what his fan was running at. His varied from 12.3 at the lowest position to 12.5 at the highest. I wouldn't think that .2 volts would make the fan turn at a different RPM. Also I heard a clicking noise coming from a relay or a seloniod near the fan, everytime we changed speeds on the motor it would click. So I guess I couldn't answer my own question with my dads truck. So can you guys please help me!! Any other ideas on how to diagnose/fix my problem would be great.

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yellow 86 Camaro
LG4 700R4
Pioneer head unit
Kenwood speakers
Infinity Beta Digital 300 amp
2 Infinity Perfect 12s

 

The most common failure of that system in these cars is a certain connector in the wire that feeds switched battery to the entire A/C control head. When the connector burns up, nothing electrical in the A/C system will work, which includes the blower and the A/C compressor. If you pull the control head out of the dash and follow the brown wire back away from the head into the dash, about a foot away from the control head you'll find where that wire from the A/C harness plugs into the main dash harness. That connector has burned up (like to ashes) in more than half of the maybe 15 or 18 cars using that system that I have owned or my family has owned in the last 20 years.

Get rid of that stupid factory POS, and put a couple of the BIG YELLOW insulated slide terminals in there.

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"So many Mustangs, so little time..."

 

RB83L69- I don't think its that because my AC compressor is working. I think it might be a relay that is out.

 

There's only one relay; the high-speed relay, you can follow it from the purple wire off your blower motor's resistors.

Oh those are what control the speed of the blower motor. The resistors are "upside down", located on top of the heater/evaporator box. Look to the driver's side of your blower motor; you'll see a 4-pin gray connector. Unplug it, and the blower motor resistors are under there, held in by 9/32" screws.

Like RB mentioned before tho, the blower resistors have nothing to do with the motor's highest speed- that runs off the relay. So either you've got a bad main connection somewhere, or both your blower resistors and high-speed-relay hookup is dead.

And that's possible; right now I have a bad "3rd speed" connection and a bad "high speed" relay.

You should try hooking that blower motor up directly to power; see if it spins. 7.8 volts should move it a bit, I think.

The hookup for the high-speed function is at the relay... I forget the wire colors so I can't be of that much help. I can tell ya tho that the red wire against the firewall, by itself, is the "source" for the high-speed power. It runs down to a fusable link on the starter motor... and goes into the relay.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

well I put in a new relay today and that didn't help at all. My volts even dropped a little down to 6.9. I guess my switch could be bad. What are these resistors you are talking about?

 

Matt,

There is a resistor array bolted into the top of the HVAC housing under the hood. The resistor array has two small hex-head screwa and a four-terminal connector plugged on to it.



Remove the connector and the two screws, then lift the resistor array out of the ductwork. Meter between all of the connectors to check for continuity. The connections can degrade, or the resistors themselves can fail if the motor gets stuck with power applied.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

[This message has been edited by Vader (edited January 03, 2001).]

 

what does it mean to measure continuity and how do you do it? sorry about all these questions, I'm still learning.

 

Leave it to Vader, a Picture says a thousand words

As for continuity, Use a Multimeter. Set it to the setting that makes the Thing Beep when you touch the Two leads. Then connect it to either side of the resistor and see if it beeps




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

well, I've checked my resitors and they are fine. I just touch the ends of the coils and they all beeped. I didn't check the contacts though. Could they still be bad? What else could be wrong. I've got a new motor, and new relay and the resistors are fine. I guess the next thing is a new switch.

 

Sometimes corrosion gets into the connections, but you said you have voltage at the motor (your first message), right?

I don't think you'd have a bad switch if you saw voltage... you could check that red wire I mentioned. It's by itself on the firewall, held high with a single screw. That comes off a fusable link from the starter motor. If you probe that connection you should see 12 volts. If you do, then put your blower motor on "high" and follow that wire as it goes thru the relay into the blower. This would just fix your "high speed", though.

Have you tried hooking the blower motor directly up to 12 volts? Maybe you got another crap motor!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!