Blower fan not working / vaccuum line maybe?

[cfern87]

Hey all. new Lumina owner here.

My fan switch is not producing any air out of the front vents. The rear fan works (just fixed that relay).
I've checked the fan itself by removing it from the firewall and it is spinning, so I know it's not the switch, fuses, the fan, etc.
As I'm reading around I'm thinking it could be a vaccuum line issue (maybe?), but I don't know much about how the vaccuum line plays with other components or what to do about it.

I need to charge the AC as well, but obviously can't do it until the fan issue is resolved.

So, I ultimately have two questions:

1. Had anyone else experienced this issue or have a knowledge bomb to drop on what it might be?
2. How can I test and check the vaccuum lines (and how do I know where they are)?

thanks in advance!

[Tech II]

Van or car?

[cfern87]

APV
1996 chevy lumina APV

[Tech II]

Is your fan switch creating four different speeds?

Do you have air flow somewhere, like the defrost?

[cfern87]

The rear fan works on all 4 speeds. the front fan does not.

I do know the AC was vaccuumed out to be ready to be charged.
The car also seems to stall when there's a fast decline in rpms, thats why im thinking vaccuum line.

Don't know why the front fan wouldn't push air even though the motor is running otherwise.

[Schurkey]

Originally Posted by cfern87

The rear fan works on all 4 speeds. the front fan does not...


...Don't know why the front fan wouldn't push air even though the motor is running otherwise.

You aren't making sense. You say the fan doesn't run, then you say it does.

I have the sense that the FAN RUNS, and it probably has all of it's fan speeds--but it doesn't blow air out the vents you choose. The air is coming out somewhere else--the defrost duct at the base of the windshield, but perhaps just somewhere inside the dash structure because a duct has gotten disconnected.

You need to be more specific about whether the problem is the fan running, or air movement at the various outlets. The fix for one is not the same as the fix for the other.

[cfern87]

The fan does run.
The air does not come out of ANY of the front vents.
The rear fan runs and air comes out of the rear vents.


When i turn the front fan on, I do not hear it at all, as I do with the rear. I do not feel any air moving.

I do no know where to begin when it comes to checking the ducts. I do know that the fact that is on the firewall turns quickly (i.e. the front fan), but the fact that there is no air coming out of any of the vents at all is confusing to me - if there was a disconnected duct wouldn't I still feel airflow somewhere?

[Schurkey]

Disconnected duct could allow air to blow around in/behind the dash area, you might not feel any air movement.

Could be blockage in the air intake for the HVAC system. My in-laws had a rambunctious squirrel that filled the air intake of their Park Avenue with nuts 'n' seeds. No air flow.

When I pulled my K1500 apart, there was a bunch of pine needles and other debris clogging the A/C evaporator air passages. I had more air flow when I dug all the crap out of the evaporator (and heater core) fins.

Any way you look at it, though, I'd expect you'd still hear the fan turning. That's the first thing I'd investigate.

[cfern87]

I do know that the fan on the firewall does spin - is that the A/C Evap fan?
I took it off the firewall, started the van, and turned the fan on. Saw it spinning. It's quiet.
When it's in the firewall, I do not hear it.

I am thinking the next step is to pull apart the dash and look for blockages/disconnects, however I don't know where to start. This is a daily driver and if I can do the job in a day that would be ideal.

Without knowing this car or taking apart the dash, I don't have confidence that that can happen.

Any tips?

[Schurkey]

Originally Posted by cfern87

I do know that the fan on the firewall does spin - is that the A/C Evap fan?

Heater, Ventilation, A/C. (HVAC)

Originally Posted by cfern87

I took it off the firewall, started the van, and turned the fan on. Saw it spinning. It's quiet.
When it's in the firewall, I do not hear it.

Suspicious. The thing should hum, and the rotation/turbulence of the air coming off the squirrel cage should be noisy.

I'm therefore curious if the fan is spinning fast enough. I would test the voltage AT THE FAN MOTOR or as close to the motor as you can get. On high speed, you should have 12+ volts. Lower speeds will have less voltage. You should have zero or nearly zero volts on the ground/metal fan motor housing.

[cfern87]

Suspicious. The thing should hum, and the rotation/turbulence of the air coming off the squirrel cage should be noisy.

I'm therefore curious if the fan is spinning fast enough. I would test the voltage AT THE FAN MOTOR or as close to the motor as you can get. On high speed, you should have 12+ volts. Lower speeds will have less voltage. You should have zero or nearly zero volts on the ground/metal fan motor housing.

It definitely turns. Is the squirrel cage the finned cylinder attached to the fan motor itself?

I did test the voltage at the fan. I forget what setting I had it at, but I do remember that I did get ~+12V on an analog multimeter upon testing. That's why I took it off; if I'm getting voltage, then I had to see if the fan was spinning.

I will run another test - one at each speed - and let you know what I get. I will do this with a digital multimeter.

[Schurkey]

Originally Posted by cfern87

It definitely turns. Is the squirrel cage the finned cylinder attached to the fan motor itself?

I did test the voltage at the fan. I forget what setting I had it at, but I do remember that I did get ~+12V on an analog multimeter upon testing. That's why I took it off; if I'm getting voltage, then I had to see if the fan was spinning.

I will run another test - one at each speed - and let you know what I get. I will do this with a digital multimeter.

Digital or analog makes no difference if the meter is accurate.

You MUST test the voltage with the motor RUNNING. Testing at all the selectable speeds is a good idea.

Don't forget to test the ground voltage at high speed. Less is better--zero is ideal, one volt is too much.

[cfern87]

I tested the voltage with my digital multimeter.

Unplugged the plug from the fan on the firewall and plugged my leads into each side terminal and started the van.

With the fan on the lowest setting and selecting "bi-lev," I got a voltage of 13.88 and when I switched to high it went to 14.00 and remained steady there.
Didn't seem to jump much until I went from the middle to the high setting.

My GND voltage (leaving the negative lead in the plug and touching the positive lead to the battery, I got consistently less than 0.1v, usually somewhere around 0.05.

[Schurkey]

Figure out a way to tap into the fan + wire WITHOUT DISCONNECTING IT from the fan. The easy but poor way is to pierce the insulation with the pointy tip of the voltmeter probe. Or install a jumper wire at a connection, so that the fan still works but you can pierce the jumper wire instead of the vehicle harness.

Put the voltmeter + wire on the power tap. Put the voltmeter - lead on the - battery post.

Run the engine so the alternator charges. Observe 'n' record the voltage on the meter while THE FAN IS RUNNING through it's various speeds.

Then put the + probe on a grounded part of the fan motor, WITH THE FAN RUNNING while you test for voltage.

In both cases the - lead is on the - battery post.

[cfern87]

Okay, I was able to tap into it by using a needle and alligator clip. I verified that I was getting voltage to that connection and that it was making a proper connection by using a continuity meter before any of these tests. I used the positive wire and battery terminal for the voltage tests.


The motor has 4 settings per the slider switch in the dash.
I used the "bi-lev" setting selector setting
All tests were made with the motor running.

1: 14.6v
2: went between 14.5-14.7
3: 14.5v
4: 14.6v

These are all prettymuch the same.
I verified that the voltage was 0 when selecting "off" on the series of buttons on the dash as well just to idiot check.


Ground voltage with the fan on (same method, except into the ground wire) gave between 0.05v and 0.11v with the positive lead of the meter connected to the negative wire on the fan and the negative lead of the meter touching the negative pole of the battery.