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AC Cold but not Blowing - Air Trickle When Driving

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Old 05-12-2022 | 06:23 PM
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Arrow AC Cold but not Blowing - Air Trickle When Driving

Long time listener, first time caller. 2008 Chevy HHR 2.4L.


Problem: AC won't blow. If I choose the AC button for using outside air, you can feel cold air barely coming out of the vents. If I crack the windows, or open them halfway, cold air creeps through the vents at about the force of the AC working on it's lowest setting. No sound, nothing running.


Related Issues: Thermostat was sticking a year ago, I replaced it. Months back, AC control knob was acting up. AC would either blow full blast, or not at all. Setting the knob to low meant full blast, twisting the knob to any setting past that, and it wouldn't blow at all (neither the heater). Now twisting the knob does nothing. Relative did some work on the steering column last year, "info" button works toggling options, cruise control stopped working. The car isn't running hot. The Check Engine Light hasn't come on since last year.


Weather is humid and in the 100's this week, expecting storms for a few days. Hoping to fix this quick.
Old 05-12-2022 | 06:50 PM
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Bad fan,bad switch for the fan not blowing.
Center stop light bulbs for the cruise control.
Old 05-12-2022 | 08:52 PM
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Sounds like the blower resistor is blown. That may be modular I'm not sure but that is what it is.
Need to check his work on the column head.
Old 05-13-2022 | 08:06 AM
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If the resister is bad the fan blows but only on high, because there is a direct path to ground.
Old 05-13-2022 | 11:04 AM
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Does the fan circuit use a resistor block or is it modular? The modules will fail like that. Resistor block failure will result in hi speed only.
Old 05-13-2022 | 03:20 PM
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Originally Posted by greg8453
Does the fan circuit use a resistor block or is it modular? The modules will fail like that. Resistor block failure will result in hi speed only.
I'm not sure. I was looking on Youtube for videos on how to replace certain parts, but only saw a 2006 being fixed.

Little side note, we have an identical 2008 Chevy HHR that was totaled out about two years ago. Unless I really need a new part, I just try to pull parts from that one.

In one video, a guy replaces a resistor block to deal with the AC only blowing at max speed. So I may go ahead and start there. If it's a resistor block, I imagine I can just swap it out with the other one.
Old 05-13-2022 | 03:45 PM
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Yours should be very much like this.
Old 05-13-2022 | 05:31 PM
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But you said it wasn't blowing at all? That is a huge difference from blowing on high only. It is a resister pack, the switch chooses the path to ground un resisted is the default. All years are the same in this.

Why not test the switch with a test lamp, cheaper than throwing parts around? The motor with a jumper wire? Just be advised; the brown wire is always hot the orange wire goes to ground by way of the switch.
test the motor: key on test the brown wire for voltage then short the Orange wire to ground, if it does not run replace motor if there is no voltage check relay #30 (BCM)and fuse #4 (underhood).
if it does run test the switch for continuity in all positions except off.

I suspect the switch because the AC compressor won't run if the fan is turned off, the BCM gets that signal from the green wire on the switch


Old 05-13-2022 | 09:59 PM
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Originally Posted by greg8453
Yours should be very much like this.
https://www.youtube.com/watch?v=ETIvRO0hYP0
I'll check it, thanks.
Old 05-13-2022 | 10:19 PM
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Originally Posted by donbrew
But you said it wasn't blowing at all? That is a huge difference from blowing on high only. It is a resister pack, the switch chooses the path to ground un resisted is the default. All years are the same in this.

Why not test the switch with a test lamp, cheaper than throwing parts around? The motor with a jumper wire? Just be advised; the brown wire is always hot the orange wire goes to ground by way of the switch.
test the motor: key on test the brown wire for voltage then short the Orange wire to ground, if it does not run replace motor if there is no voltage check relay #30 (BCM)and fuse #4 (underhood).
if it does run test the switch for continuity in all positions except off.

I suspect the switch because the AC compressor won't run if the fan is turned off, the BCM gets that signal from the green wire on the switch
Well the first problem that showed up months back, was that it would only blow on high. The weather was such that I wasn't using the heat or AC anyway. So of course, it stops blowing altogether once the temp hits 105. But I mentioned the issue with the AC only blowing at high before it ultimately shut off, in case that helps anyone diagnose the root of the problem based on what happened first.

I let someone use my multimeter and haven't gotten it back. I do have a non-contact voltage tester pen (12V-1000V/48V-1000V). But I've only used that to diagnose issues with AC outlets in our home. I don't know enough about electrical diagnostics to know if it would even work for a vehicle. Is the test lamp the deal that looks like a screwdriver but with a probe?




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