New blower motor not functioning....must be something else..

[Eagle]

 

I disagree about pulling the dash switch, and I told you changing the resistor pack wouldn't fix it. If you have voltage at the fan connector, and the fan motors run when hot-wired, the ONLY possible cause of the problem has to be the ground. There are only two wires here -- power in, and power out. You have verified that you have power in, so the problem has to be on the power out side.

 

He said he had no voltage at the blower fuse.

 

Posts number 3 and 8. He said he has voltage at the fan connector.

 

Rohls -

 

Are you certain you have voltage at the fan connector? You should be able to read four different voltages, with the fan switch set for Low, Medium, High and Full speed. Those four voltages HAVE TO be different, because that's what controls the fan speed. Test again, and report all four voltages. Also tell us how you're testing.

 

Assuming you have voltage at the connector, try using a Scotchlock tap off the ground wire and running a new ground wire directly to the battery. See if the fan works that way.

[Rohls]

Will do! Thanks so much.

 

I will hopefully get a chance tomorrow to look at it again and report back.

Thanks everyone...!

[Rohls]

Ok, I checked a few things today,

 

With the grond wire from the MOTOR SIDE connector wired to the negative of the battery via alligator clips and the positive if the TRUCK side connector (like normal) to the positive of the motor connector...I still don't get anything. Here I was trying to rule out the grounding issue, and I think I did...right?

 

I took the voltage readings as suggested above...I plugged the negative of the meter into the black wire at the motor connector, the positive of the meter into the green wire at the connector....put the meter outside facing in to the cab. Switch the key to the acessory position (that's alright, right?) and noted the following readings...

 

on the BI-LEVEL setting:

Off=0 V

Low=11.69 V

Med=11.72 V

High=11.57 V

 

On the HEAT Setting:

 

Off=0 V

Low=12.09 V

Med=12.09 V

High=12.09 V

 

On the VENT setting:

 

Off=0 V

Low=12.07 V

Med=12.07 V

High= 12.07 V

 

I take it the motor has to have 12.4 V or higher to kick on, right? >>>>Could the battery be the issue here?<<<<<< :bowdown:

 

I have no more ideas....except for the switch itself...if I'm not getting very different voltages....could that be the culprit?

 

What do other people get for values here?

 

Thanks! . :MJ 1: .

[Eagle]

I can tell you the values for the resistors, but I don't trust my math for figuring out what the voltage should be.

 

Lo = 2.39 Ohms

M1 = 0.89 Ohms

M2 = 0.34 Ohms

Hi = 0 Ohms

 

You should definitely not be getting the same voltage for all the switch positions. The resistors drop the voltage, and it's the voltage getting to the fan that controls speed. You also should not be getting zero volts with the switch in the OFF position, because the fan speed control doesn't have an OFF. The lowest speed is still a speed -- the fan only turns off when the mode selector (Heat/Vent/Hi-Lo) is turned to OFF.

 

I just did a bit of refresher training on basic electrical theory. Amperage figures into the equation, and what I just read suggests that resistors DON'T drop the voltage in a circuit unless there is something else in the circuit that's using power. If I understood that correctly, with just the multi-tester connected but no fan in the circuit, the voltage would always be equal to the battery voltage. Which is consistent with your results.

 

I'm baffled. Your tests appear to suggest that you have power to the fan motor, ground from the fan motor, the fan motor runs when hot-wired -- but it won't run when plugged into the chassis wiring harness. We're obviously missing something here.

 

Do another test for ground. Unplug the motor. Connect your tester to the negative terminal of the body side of the fan connector, and connect the other lead from the tester directly to the negative terminal of the battery. See what the resistance reading is.

[Rohls]

I can tell you the values for the resistors, but I don't trust my math for figuring out what the voltage should be.

 

Lo = 2.39 Ohms

M1 = 0.89 Ohms

M2 = 0.34 Ohms

Hi = 0 Ohms

 

You should definitely not be getting the same voltage for all the switch positions. The resistors drop the voltage, and it's the voltage getting to the fan that controls speed. You also should not be getting zero volts with the switch in the OFF position, because the fan speed control doesn't have an OFF. The lowest speed is still a speed -- the fan only turns off when the mode selector (Heat/Vent/Hi-Lo) is turned to OFF.

 

I just did a bit of refresher training on basic electrical theory. Amperage figures into the equation, and what I just read suggests that resistors DON'T drop the voltage in a circuit unless there is something else in the circuit that's using power. If I understood that correctly, with just the multi-tester connected but no fan in the circuit, the voltage would always be equal to the battery voltage. Which is consistent with your results.

 

I'm baffled. Your tests appear to suggest that you have power to the fan motor, ground from the fan motor, the fan motor runs when hot-wired -- but it won't run when plugged into the chassis wiring harness. We're obviously missing something here.

 

Do another test for ground. Unplug the motor. Connect your tester to the negative terminal of the body side of the fan connector, and connect the other lead from the tester directly to the negative terminal of the battery. See what the resistance reading is.

 

Thanks Eagle.

 

So I just went out there again....

 

I first tested the voltage at the connector..= the same readings as before.

 

I flipped the A/C to test, heard what I imagine was the A/C compressor relay (under the passenger dash near risistir pack) click.

 

I then tested the voltage again and ALL VOLTAGE in all positions DROPPED TO 0.0XX VOLTS. Frustrating...

 

I now have little to no-voltage at the connector...

 

Could the heater control switch be bad? A/C relay effecting things...? What else in the world is in this heater circuit?!?

 

BTW, here is a pic of my heater control switch...I have no OFF selection for the heat/vent selection, only fan speed.

 

I also tested the NEGATIVE BODY-SIDE connector to BATTERY NEGATIVE and the resistance reading was 0.4 Ohms.

 

[Rohls]

The blower switch is p/o the dash HVAC assembly. I think the next step is to pull the dash bezel then the HVAC control assembly and inspect it. Make sure 12V is present on the harness connector and is mated properly, and check that the switch has continuity in each position with your ohmmeter.

Thanks all!

 

After a lot of searching and replacing parts, the connection right at the blower was intermittent! I fixed this and the blower is solid now. Thanks again!