I'm so confused, Re: AC, blower, resistor, etc...

[takearushfan]

Hi all...
I'll give some background. My AC was doing this thing where, no matter what speed it was set on, the force the air was blowing at would vary/be intermittent. For example, you'd be driving for a few minutes with it set on high and suddenly it's still blowing but at a very low force. Let's say I'm then driving around a bit more, hit a bump in the road and it goes back to the force it was supposed to be at. Though annoying, I didn't mind because it at least worked somewhat... then it died, completely.
I got it "repaired" a month ago but all they did was get it back to functioning "somewhat" rather than being completely dead. The varying force was still an issue. Like an idiot I thought "whatever, at least it's mostly fine now". Well, now it's back to being almost completely dead again and blowing hardly at all.
If it were you, would you suspect this as the blower itself, the resistor, both or something else? I'm trying to determine which parts/parts to save up for to try to do this myself.
If something as simple as a bump can change the force, might it just be loose wiring somewhere? If so, where?
In other words, what would you try first, second, third, etc? I'm not in a place where I can afford the cost of labor. I can barely afford the parts.
Thanks for your patience. I'm sorry for the tedious post. I know nothing of cars, mechanical terms, etc

[andrewclaus]

I remember writing this reply last month:

"...the blower speed ..is controlled by the rotary switch on the dash and a resistor. If it's affected by bumps in the road, it may be a loose contact in the switch. Can you make it happen by bumping the dash with the palm of your hand? That's called "percussive troubleshooting."

...the part number for the A/C control assembly for the Matrix is 55900-02150. The switch is not available by itself."

I'd look at repairing or replacing the rotary switch. The Vibe may use a different switch than the Matrix.

[SSizler]

If the fan speed sounds the same when the air flow changes you probably have a blend door problem.
There are 2 doors, hot / cold and recirculate.
I would check the operation of the doors and actuators.
Maybe something is broken or disconnected.
Just something else to consider....

[takearushfan]

If the fan speed sounds the same when the air flow changes you probably have a blend door problem.
There are 2 doors, hot / cold and recirculate.
I would check the operation of the doors and actuators.
Maybe something is broken or disconnected.
Just something else to consider....

I had that too but that part they did repair successfully.

[joatmon]

You say that sometimes the fan blows with low force even when the knob is set to high. When the fan is off, but you're driving around, the car movement will push some air though the system, giving the impression that the fan is running at low speed. To determine if the fan is actually running but at a low speed, when the fan is in low flow mode even with the speed set to high, set the fan speed to off while driving and see if there is any change in the airflow. Or pull over and stop and see if there is any change in the airflow. If you're driving and the fan is set to high but running low and you switch the control to off and the airflow noticeably decreases, then Its a more obscure problem, maybe some freakishly unlikely issue with the fan speed control switch.

There is no way a blower resistor failure can cause the fan to run slow when the the control is set to high. Resistor failures can make the fan not run at all when set to low speeds, but when the control is set to high, the resistor is bypassed and has no effect. The resistor is not causing the symptoms you describe.

Based on user posts here, having the fan stop/start when subjected to a physical jolt is a reasonably sure sign that the blower motor itself is failing.

Looked at one autoparts chain store and a replacement blower motor is a little over $150. I know advance auto usually offers some discount for online orders. Also looked at car-part.com, a nationwide searchable database for junkyard inventories, and a used one from a wreck (near me, anyway) runs about $50. A used one may not last as long as a new one, but its an option if money is really tight.

I have never replaced the blower motor in a Vibe, but there is a decent write up on how to do it, from striker1211 in viewtopic.php?t=39183 Looks fairly straightforward, if you've got the right size tools. Didn't look, but there are probably several youtube videos on how to replace it.

[takearushfan]

You say that sometimes the fan blows with low force even when the knob is set to high. When the fan is off, but you're driving around, the car movement will push some air though the system, giving the impression that the fan is running at low speed. To determine if the fan is actually running but at a low speed, when the fan is in low flow mode even with the speed set to high, set the fan speed to off while driving and see if there is any change in the airflow. Or pull over and stop and see if there is any change in the airflow. If you're driving and the fan is set to high but running low and you switch the control to off and the airflow noticeably decreases, then Its a more obscure problem, maybe some freakishly unlikely issue with the fan speed control switch.

There is no way a blower resistor failure can cause the fan to run slow when the the control is set to high. Resistor failures can make the fan not run at all when set to low speeds, but when the control is set to high, the resistor is bypassed and has no effect. The resistor is not causing the symptoms you describe.

Based on user posts here, having the fan stop/start when subjected to a physical jolt is a reasonably sure sign that the blower motor itself is failing.

Looked at one autoparts chain store and a replacement blower motor is a little over $150. I know advance auto usually offers some discount for online orders. Also looked at car-part.com, a nationwide searchable database for junkyard inventories, and a used one from a wreck (near me, anyway) runs about $50. A used one may not last as long as a new one, but its an option if money is really tight.

I have never replaced the blower motor in a Vibe, but there is a decent write up on how to do it, from striker1211 in viewtopic.php?t=39183 Looks fairly straightforward, if you've got the right size tools. Didn't look, but there are probably several youtube videos on how to replace it.

That all makes perfect sense, thanks. Yeah, it seems it's the blower itself then, when using the step by step elimination troubleshooting like that. I'll look into the $50 range ones and try the guide out, thanks