Heat and A/C not blowing air

Hi Dwayne,

If the blower does not come on in any speed then the first thing is the resistor but you said you replaced this. If this is the case, then we need to check for 12 volts at the blower motor. If you have 12 volts there then most likely it is the blower motor.

The easiest way to test is to just jump power to the motor and see if it kicks on. The blower motor has two wires as you will see in the wiring diagram and you want to just jump a 12 volt feed to the supply wire. If it doesn't come on then you need a new blower motor.

Let me know what you find on this wire and we can go from there.

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

So if you tested power on the highlighted wire at the blower motor itself and you had 12 volts, then it is either the resistor or the blower motor itself. To determine which it is, test the other wire at the blower motor in each fan speed. You should see the power increase as you switch through the fan speeds. If you don't have power at all then it is your resistor. If you do have voltage on the other wire, then the blower motor is the issue.

Due to you already changing the resistor and the blower does not work on any setting, I would assume the blower motor is the more likely issue.

Okay. Please go to the blower motor and turn the vehicle on, turn the blower on each setting and tell me what the voltage is at the blower motor on each wire. They should be a dark blue wire, and a dark blue with yellow.

On the Dark Blue at the blower:
Lo speed -
Mid 1 speed -
Mid 2 speed -
High speed -

On the Dark Blue with yellow:
Lo Speed -
Mid 1 Speed -
Mid 2 speed -
High speed -

Lets get these and go from there. We need to make sure we have proper voltage in each setting. If not, we can go backwards in the system. I imagine you have a wiring issue if the blower does not come on at all and the motor and resistor have been changed. However, at this point we need to go systematically or we will surely get lost and just throw more parts at it.

I included the wiring diagram with some drawings on it that explain the power flow. My red line is 12 volt supply. The blue is the power that varies from the control module through the resistor to the blower motor.

Thanks

Okay. I suspect you have an issue with the TIPM not supplying power but we need to prove out the rest of the system.

Do you know how to jump power to the blower motor? Basically, you want to take battery voltage and supply it to your DB wire just long enough to test the different fan speeds. If you let this run for more than a minute or two, it can burn up your motor because it is not a protected circuit.

If you put the fan on speed setting one, then turn the ignition on, jump your 12 volts to the DB wire and the fan should come on low. Then check each fan speed. If each works properly then you just confirmed that your motor, resistor, and AC/heat module are functioning.

This means you have a voltage supply issue. So it is either the supply module (TIPM) or the wiring in between. At this point, you will want to take the wiring and measure resistance from the TIPM to the blower motor. You do this by disconnecting the circuit at both ends, set your meter to ohms and probe the circuit from both ends. You should have less than 0.5 ohms. If you have a wiring issue, I suspect this will be open or infinite resistance. Let me know the results of this and what that resistance reading is.

Well, you run a jumper wire from the battery to the motor and jump it to your DB wire.

However, if you are not familiar with this, then I would suggest asking around to see if anyone you know is familiar with this. This is moderate to high electrical diagnosis and it is easy to get confused.

I work with many techs that do not understand this type of stuff either so it is not the easiest thing to do.

I suspect your TIPM is the issue but I do not want to tell you to get that part without performing these tests because it could also be a wiring issue.

Just to confirm, when you tested the two wires and found 0 volts on both, the vehicle was running and the fan was on correct?

You can get jumper wires from an auto parts store. However, I would strongly suggest seeing if anyone that you know is familiar with this. There are many ways to do this but the easiest is to back probe the connector at the wiper motor with a T pin and then use a jumper wire with alligator clips and run it to the battery and touch the other alligator clip to the positive battery post.

If you have not done this then not only could you damage the connector but if you don't make good contact then we will get a result that leads us down the wrong path.