Resistor pack
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bleu7
Member
- Mar 27, 2012
- 36
tmm217 said:
so neither of these would be able to help me measure the blower motors current?
Digital Clamp-On Multimeter
Digital Clamp Meter
No. Harbor freight doesn't have DCA meters.
The Craftsman is pretty much the best deal for a name brand DCA meter going. Already did the comparison shopping.
The Craftsman is pretty much the best deal for a name brand DCA meter going. Already did the comparison shopping.
Many, if not most, handheld meters have a 10A DC function, but it's a shunt resistor type, where you have to put one of the leads in different receptacle, and you have to cut or disconnect one of the wires you're measuring the current in, and you put the meter in series with the circuit. "Series" means "in-line" which basically means the meter replaces a short length of wire in the circuit.
Since these blower motors take more than 10A, using such meters on this circuit can burn the meter's shunt resistor. There are other ways to measure the voltage across a lower value (1 milliohm) shunt resistor, but accurate 1 milliohm resistors can be pricey. I designed a circuit that uses a 1/2 milliohm shunt resistor to measure 500 Amp pulses (10 microseconds long or so) on the high voltage side of a 600V circuit. Measuring the current was easy compared to getting the measurement answer down off the 600V level it was sitting on. Used optoisolators and a floating voltage source as a trick. Oh, and it had to be 1% accurate, but that spec is actually a breeze compared to other circuits my company designs. (0.1% accurate current source and measurement at less than 1 billionth of an amp)
Since these blower motors take more than 10A, using such meters on this circuit can burn the meter's shunt resistor. There are other ways to measure the voltage across a lower value (1 milliohm) shunt resistor, but accurate 1 milliohm resistors can be pricey. I designed a circuit that uses a 1/2 milliohm shunt resistor to measure 500 Amp pulses (10 microseconds long or so) on the high voltage side of a 600V circuit. Measuring the current was easy compared to getting the measurement answer down off the 600V level it was sitting on. Used optoisolators and a floating voltage source as a trick. Oh, and it had to be 1% accurate, but that spec is actually a breeze compared to other circuits my company designs. (0.1% accurate current source and measurement at less than 1 billionth of an amp)
bleu7
Member
- Mar 27, 2012
- 36
CaptainXL said:
understood, i suppose i should just change out, all three parts then, motor, resistor and connector, since my connector's red wire looks just as the one in that video. I was going to go buy the craftsman meter, however I might as well install all three parts.
fuses and relays all look good btw.
thanks for the replies!
bleu7
Member
- Mar 27, 2012
- 36
wesman43 said:Yep same here. I ordered a new blower motor and got a new resistor (for free) from advance yet again but this time I'm not playing with fire
Hey so i was looking at the blower motor at advance and one of the reviews says, that the motor is smaller than the one that comes off, is that normal??
wesman43
Member
- Apr 30, 2013
- 199
bleu7 said:
I mean if still fits and you can mount it, and it works, then I really don't see a problem, unless it's power is different too.
Edit: Don't buy the one advance has, it has a 2.6 out of 5 rating and people say it does not in fact line up. So I would steer clear of it. I bought the resistor pack only from them because i used the p20 code for 20% off and it had a good rating.
bleu7 said:
If the motor tests bad then yes get all three parts. If the motor is good then just get the resistor and connector. My motor tests good with the Craftsman meter I just got. Worth the money. Just saved myself the cost of buying a new motor. Will test the motor again in the winter just to be sure.
bleu7
Member
- Mar 27, 2012
- 36
CaptainXL said:
CaptainXL said:
Well I have a 40% coupons for advance auto parts, and also Rockauto has the motor from $46-$64, therefore the price of the motor would be just about the price of the meter.
Anyone recommend
TYC #700231
Four Seasons #35237
I am in no hurry to get it fix, so I wouldn't mind waiting on online delivery. Specially since the only local part available that has any feedback says it is smaller, noisier and weaker than the original, or so it says that on the reviews at advance auto parts.
Oreillys and autozone have no feedback on their parts.
bleu7 said:
Yes, but I will be using this meter to test other things as well such as starter amp draw and other battery related stuff. Its also a full multimeter (granted it aint RMS) but its better than my 20 year old RadioShack meter which has served me well. It can also test capacitors, temperature, duty cycle in Hz (pulse width modulation)
bleu7
Member
- Mar 27, 2012
- 36
CaptainXL said:
So I've decided to buy the craftsman meter, do I have to first change out the burnt out resistor and connector and once that's working test the motor or can I test the motor while the resistor and connector aren't allowing the motor to blow??
I know that may be a dumb question.
bleu7 said:
You need to get 12 volts to the motor. Weather you do that with a new resistor pack and connector or not is up to you. In other words you can take the motor out and bench test it connected directly to a battery or repair the circuit leading up to the motor. The goal is to test it with no resistance in series.
I never should have read this thread. I got in my Envoy on Friday Morning and speed 5 did not work on the blower. I thought great I just read about this issue. I know what do. The vehicle is not my daily driver. I am sure it worked when I last used it. I could hear the relay clicking when speed 5 was selected. When I got to work I went online and ordered a resistor back and picked it up on the way home. I got home and went through all the above. Check fuse 35 and the switch. measured voltage at the leads to the motor. on speed one is was 3V and it stepped up on each setting. Go to 5 and it was 12.5V. I thought it's getting full voltage why isn't the motor running must be some kind of bleed through. I took the resistor out all the connectors looked perfect. Put the new resistor in and speed 5 was back. Did a current draw test and it was drawing 18 amps on speed five. so all is well.Just an FYI. The motor drew 16 amps when the key was on the run position. When the engine was running the blower motor drew 18 amps. The extra voltage available will increase the amp draw. To get an accurate reading make sure your engine is running.
bleu7 said:
You could cut the motor connector off the old resistor pack to connect the the motor directly to a 12v battery.
bleu7
Member
- Mar 27, 2012
- 36
Team Dougherty said:
Just an FYI. The motor drew 16 amps when the key was on the run position. When the engine was running the blower motor drew 18 amps. The extra voltage available will increase the amp draw. To get an accurate reading make sure your engine is running.
You could cut the motor connector off the old resistor pack to connect the the motor directly to a 12v battery.
Take the motor off the car though right, I am not trying to blow fuses or such.
bleu7 said:
You do not need to remove the motor from the car. In fact, i think, it may not give an accurate current reading if you do as there would be no load on the motor if it is not in the duct work.
I would just cut the motor leads off of an old resistor pack, put longer wires on if need be, and connect right to a battery. There is no need for a fuse or breaker for this test.
bleu7
Member
- Mar 27, 2012
- 36
Team Dougherty said:
Well I wished I had read this before today, I changed all three parts yesterday.
Connector, Resistor & Motor.
Got my ac back up after a while of not having it and in houston that's a horrible thing to go without for even a day.
However, one thing has gone wrong, which I can't find a single thread on here or on the web. My speed 1 isn't working. All others work fine, I can not remember 100% if speed 1 worked fine right after I changed everything.
Ideas anyone? Only speed 1 doesn't work at all, doesn't even engage the motor. All others have no issue at all.
djthumper
Administrator
bleu7 said:
Are you sure the wiring is correct to the plug? You may have a bad connection on one of the wires. If everything looks fine there I would do some tests with the resistor pack and the switch.
djthumper
Administrator
You need the schematics, a meter, and a bit of experience with electrical troubleshooting. I don't think we have a tutorial that starts by assuming no experience.
Without a meter, no hope.
Without a meter, no hope.
Check the blower motor terminal first to see what voltage you get on each speed. Then work backwards toward the switch. The schematic will suggest what to check next after each measurement reveals if it's right or wrong.
djthumper
Administrator
wesman43 said:
The one in the Hayne's manual should work fine. It should look something like this one here.
View attachment 29443
Found this one before, roadie supplied it a long time ago.
