Fluctuating blower motor
 

Guys,

I'm pretty sure this topic has been covered but my search is not revealing anything. I think my search string is not adequate so if this issue has been covered in the past, please point me to it.

The blower motor in my '92 has been fluctuating. Rather than trying to explain the symptoms, I made a short video clip of it. The video will show you the fluctuating speed of the blower as well as the dimming of the lights. There is no discernible blower related squeaks or odd sounds coming from the blower area. Even if I select a fan speed manually, the symptoms still continue to occur. As you can see, the engine idle speed is very steady.

Let me know your thoughts!

Thanks.

Video link

Re: Fluctuating blower motor
 

Usually oiling the bearings works.
I use high temp turbine oil when I do it. Only once did I have to replace the fan motor in my svx and that was on the one with 220,000 k miles on it. The lower bearing can be oiled without actually removing the blower but better to just get the thing out and work on top as well.

Keith:cool:

Re: Fluctuating blower motor
 

So this is a blower bearing issue, got it. What explains the light dimming, too much current draw?

Re: Fluctuating blower motor
 

At and near idle, the pitch of the blower motor in my silver SVX actually changes with the flashing of the blinkers. The headlights pulse in time, too. In 25,000+ miles (one new battery and one reman alternator later) this car has yet to leave me walking, so I just chalk it up to another frumpy old-car oddity. In this case, it seems unlikely the blower motor bearings would be suspect.

dcb

Re: Fluctuating blower motor
 

Yeah, i agree with you. I don't think it's a mechanical issue with the blower. I took a two hour drive yesterday and the symptom went away during the drive. I'll keep investigating. I'll see if there's a code I can pull.

Re: Fluctuating blower motor
 

I've always figured it to be a problem with electrical resource allocation when the alternator's putting out its least. I've had zero electrical troubles from this car (one alternator failure aside) and its Econo-Jolt Deeluxe battery is almost 4 years old. So this is definitely Small Stuff. But I wouldn't mind knowing why it does this.

dcb

Re: Fluctuating blower motor
 

I recall threads on other topics referring to an insufficient ground. Could that be it? I also notice a very slight fluctuation in the blower motor near idle. I was hesitant to post a topic on it because I knew it would invite the old "it is probably a blown headgasket" response. After all, if a slowly responding 14 year old O2 sensor points to a bad headgasket then why not a fluctuating blower?

Re: Fluctuating blower motor
 

Could simply be an alternator problem... Does it fluctuate when you are driving steadily down the road. The "bearings in the blower are bronze bushings that are made to absorb oil from a wick, not roller or ball bearings. When the wick runs out of oil, there could be a problem of fluctuating blower rpm because of the extra heat causing the bearing to grip the rotor shaft. Normally it would not make additional sounds unless the wear was so excessive that the rotor actually was dragging.
Driving steady and observing the same think would give you a better clue. Idling rpm with would probable make the alternator more suspect.

Good luck,
Keith:cool:

Re: Fluctuating blower motor
 

Hi Tony... Does that reply mean that we are communicating again:confused: Actually, I think I have enjoyed the "peaceful co-existence" better.

I think you might be on to something, Tony! In your case, the fluctuating could be a normal functioning of the system, depending on the accessory you are using. Maybe your only problem is your "blown head gasket. :D

Oops, forgot about the "squeaky door" hinge, that you can't work out where to put the oil!

Keith:cool:

Re: Fluctuating blower motor
 

I have some more data points from driving the car out of town for work in the last couple of days.

- setting the speed on low or med has no effect on the blower oscillation (better word that fluctuations, I think). Still oscillates.

- setting the speed on high, the blower is a steady high speed. However, you can still make out the dimming of the HVAC indicator lights.

- start car, setting on ECON, drive for about five min on hwy, results in the system correcting itself. But this seems to be a hit and miss.

- setting on VENT, speed on LOW/MED - same oscillations.

Also, my batt voltage is spot on during engine ON so I'm ruling out the ALT.

Yes the blower does fluctuate while driving steadily down the road. Adding more load to the ALT doesn't seem to effect the symptom.

This is not a blower bushing issue because if it was I'd think there should be a difference in pitch of the blower sound. Still, I'll pull the amps during operation to see if it's pulling higher amps than normal. I'll also drop some 3 in 1 oil just to rule it out for sure.

Ground? Could be a possibility. A bad ground can cause all sorts of headaches and a PITA to troubleshoot.

Can someone tell me how to pull the HVAC code pls?

Re: Fluctuating blower motor
 

Click HERE

And the complete climate control diagnostics from the FSM can be found HERE. The self-diagnostic procedure explained on pages 9-10.


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Re: Fluctuating blower motor
 

Awesome, thanks.

update
 

Just an update from the drive to work this morning, about 25 mins

ECON, 71 deg - blower functioned perfectly for the entire drive.

When adjusting the temp dial up or down, the system oscillates, light flickers then tries to hold steady. I took a video of this with a diff camera and it's not uploading so I'll do it when I get home this eve.

This leads me to believe that an electrical issue of some sort is at play here. I'll pull the codes, if any and report back.

thanks.

conclusion!
 

well, my problem of fluctuating blower motor has been resolved. Along with this problem, I was having an intermittent A/C operation. The system had a mind of its own and decided to come on and cool down the car as I pulled into my driveway :mad:

The main HVAC control panel was pulled out slightly while still hooked up and it turns out that there is a problem with this unit. While driving, I'd turn on the a/c and nothing happens. Then I fiddled with the control unit and the a/c would come on. It behaved like a loose connection inside this control unit. The two connectors were fine as well as the pins.

After replacing this unit from a '96, all is well. The A/C works fine, the blower works as needed. No more codes telling me that the Intake motor is not working.

The problem is that the '96 control unit fascia has a different color/tone than my '92. Not a big deal but an OCD like myself is having an issue with that :rolleyes:

Removal of this unit is a minor PITA. The FSM says to take off all kinds of stuff. I chose to to remove the plastic pieces in front of the stereo, upper center (large) vent, removed the three screws (upward direction) of the instrument panel trim, and removed the three button defrost/hazard switch panel. The control unit comes out sideways rather than straight out. Just do all this on a warm day so nothing snaps or breaks! :tard:

Cheers.

Re: Fluctuating blower motor
 

Glad it worked out well!!

Keith:cool: