Hello, all
Have a 99 Eddir Bauer Expy with 220K miles & EATC. A/C blower not working, even on "high" to bypass the speed sensor.
I have power to the blower motor, and the speed sensor switch inside the engine compartment.
I replaced the blower motor and checked the blower motor relay in the engine compartment. I can hear a "click" if I put the EATC blower switch on high, as if it's calling for power.
All the plugs look clean, no corrosion and no sign of burnout.
I'm stumped. Any ideas?
The a/c itself is working, as the rear fan is busy pumping out cold air. It's Florida and we are getting to the hot season.
Any help is appreciated.

 

You mention you have power to the blower motor, do you mean with the EATC turned on and calling for the fan there is power to the pink/white wire at the blower motor? What were you using for ground?

The electronic blower motor speed controller actually controls the ground to the blower motor, so you can have power (directly from the blower motor relay) but if there's no ground (orange/black wire at blower motor) through the controller, the blower motor won't run. Have you confirmed that that ground for the speed controller is good (black wire)?

-Rod

 

I just used a voltmeter, set it to 200ma DC and was getting 190 indicated when eatc was on, then 30 when it was off. I replaced the eatc module attached to the blower motor a few years ago (I had the no fan unless on high symptom then). I am getting no fan at all now. As mentioned in the original post, I can hear a click from the EATC module in the blower motor when turning it on or adjusting fan speed wheel. I came across another relay box under the air filter module, and some other posts indicate that there may be a relay in there, but others say not if you have EATC.
As always, I appreciate the help

 

Okay, so you're getting current to the EATC, but you didn't check to see if you actually have power to the blower motor. That could be your next step, use a known good ground and check for voltage (~12.5Vdc or more) at the pink/white wire. If good voltage, then move your black meter probe to the orange/black wire and confirm you have a small or no voltage reading with any of the fan speed settings. If you have voltage on the pink/white wire but no ground, the problem is with the speed controller circuit. If there is no voltage on the pink/white wire with a known good ground, then the feed to the blower is the problem.

-Rod

 

i worked on a 2004 Chevy truck that burnt the ground connection on the fender wall and blower had voltage, but no ground path... to back up shorods idea...

 

Tried the pink/white had 10.2 vDC (vehicle not running), and 12.3 VDC while truck was cranked. I'm stumped. To recap: New blower motor, voltage seems good at EATC Module, Voltage good to blower motor. Compressor working, rear cabin fan good, but blower doesn't run.
As always, all the help is greatly appreciated
G

 

Did you measure that voltage across both wires to the blower, or were you using a known chassis ground? You'll want to test across both wires to the blower. Even for the engine not running, 10.2 volts is quite low. It sounds like there may be some resistance in that circuit, possibly due to corrosion somewhere. I'd suggest you try measuring across both wires to the blower, then try using a test light (which will load the circuit some), and you could also try powering the blower directly from the battery to make sure the blower will in fact run. It sure sounds to me like you have high resistance in the circuit to the blower motor.

I haven't heard if you've confirmed that you definitely have a good ground as mentioned in posts #2, 4, and 5 above.

Also, the current readings you listed in post #3 above don't really make sense to me, are those the current draw from the EATC or the blower motor circuit? If to the blower motor, that current draw is WAAAAY too small. The blower motor will require several amps, not just a few hundred milliamps.

-Rod

 

I checked again this morning. 12.7 v at pink/white, 0 at black/orange wire. I pulled blower motor and direct wired to battery & chassis ground and it spun right up. Where do I go from here?

 

checked pink/white with engine running, 14.7volts, no change when we change fan speed from switch on dash, either max a/c or auto a/c and changing fan speeds. 0 volts on black/orange when we do the same thing

 

I assume you mean by across both wires was put both voltmeter contact points into the pink/white and orange/black on the plug that connects to the blower motor plug? I'm fairy handy, but not experienced checking voltages and grounds. I just checked across both wires to blower, engine running, fan on medium, a/c set to "auto". voltmeter was at 20vdc, got a reading of .03 not a typo decimal zero three.

 

Correct, I meant testing with your meter across both wires to the blower motor. In your prior post it sounds like you connected the black lead of the meter to a chassis ground and the red lead of the meter to the pink/white, then moved the red lead to the orange/black.

Now that you've measured with the red lead in the pink/white and the black lead in the orange/black, you are getting a reading of 0.03 Vdc which indicates the problem is in the ground circuit. With the automatic climate control, the solid state blower motor controller limits the current via the ground circuit. Your most recent test would suggest the problem is either with the solid state blower motor controller or possibly the connection at the motor controller. The solid state motor controller is NOT the same thing as the EATC/DATC controller where you select the temperature and fan speeds. The motor controller will be mounted in the plenum near the blower motor.

-Rod

 

The block unit bolted into the blower housing itself? I replaced that a few years ago, and I was under the impression that when that unit goes bad, you get the "no fan unless on high" issue, as the high fan speed setting bypasses the EATC assembly in the blower motor housing. I put the voltmeter on the plug that goes into the EATC unit on the blower and got the following: 0 volts when the probes were on the large red wire and connected to any of the three, smaller wires on that plug. Connect the probes to the Black wire, I got the following: 12.3v, 12.8v and 13.09volts when attasched to the three smaller wires, I think they are white, red/white and orange/white

 

With the manual climate controls there is a separate relay for high speed. However, with the EATC all blower motor speeds are controlled through the blower motor speed controller. Per the wire functions, it would appear there is a separate circuit in the controller for high speed.

The blower motor speed controller is located under the hood near the blower motor. It will have 5 wires to it, black (ground), tan/orange (speed controller feedback), white/pink (high blower relay), brown/orange (speed controller output), and orange/black (motor input).

-Rod

 

I checked those wires, not because I know what to look for, but just to see what's up with those and to tell you what I found. On the EATC module plug, there are two thick wires, (one black), and three thin wires. The only time I got voltage was when I bridged the gaps with the voltmeter probes across the black and to the three, thinner wires. I dont remember the color combinations, but what you described sounds right, I'm just at a loss what to do now.
As always, all help is appreciated

G

 

One thing you could try is to unplug the blower motor controller connector, then jumper from the Orange/black wire to the Black wire in the connector. With the EATC set to run the blower, you should get full blower speed this way. If this works, you know the blower motor and the wiring between it and the motor controller to ground is fine. Once you've determined this you're basically down to determining if the issue is the blower motor controller (most likely) or the EATC and its signal to the blower motor controller.

I'm not totally clear on the operation of the signals to the blower motor controller. I'm not sure if the EATC provides a PWM signal to the blower motor controller or if it provides a varying voltage to the motor controller and the motor controller then generates a PWM signal to the blower motor. If the signal from the EATC is supposed to be a PWM signal, you'll really need an oscilloscope to determine if the signal from the EATC is correct.

Once you determine the blower motor and ground to the speed controller are good, you might want to disconnect the motor controller again, connect the black lead of your multimeter to a known good ground, then connect the red meter lead to the white/pink wire at the connector. Turn the fan speed on the EATC to the highest speed and see if you get a voltage reading on your meter. Turn the blower motor speed down and see if the voltage on the white/pink wire goes away. If you do not see voltage on this wire when in the high speed setting, then connect the red meter lead to the red terminal of the battery and connect the black meter lead to the pink/white wire. Repeat the checks with the setting on high fan speed versus a lower speed setting. If you now get a reading on high speed only, then you can be pretty confident that the EATC is working properly and the issue resides with the motor speed controller.

-Rod