A/C Fan is "gusting"

[TXSUT]

Anyone else experience an inconsistent airflow coming from the vents? With no apparent pattern, I'll get a sudden "whoosh" of air, then it'll settle back down to normal. Seconds later, another whoosh. Happens all the time. Took it into the dealer for that and a cooling problem, which they fixed, but I still have to airflow problem.

Thanks,

Pete

[TXSUT]

Anyone else experience an inconsistent airflow coming from the vents? With no apparent pattern, I'll get a sudden "whoosh" of air, then it'll settle back down to normal. Seconds later, another whoosh. Happens all the time. Took it into the dealer for that and a cooling problem, which they fixed, but I still have to airflow problem.

Thanks,

Pete

[KenP]

If you have the a/c set to "Auto" it may be normal. The fan speed will kick up and down. It takes time to get used to it. So there may be nothing wrong. If you manually set the fan speed and it is doing it, something is wrong.

[TXSUT]

Thanks Ken, I should have specified that this is in "manual" mode.

-Pete

[LasVegas]

At the rear of your H2 behind the applique trim on the drivers side is a ventilation pressure relief valve. If it is sticking, it will appear that your a/c blower is surging. What you describe sounds like it is building excess pressue, then releasing. When that happens you'll feel/hear a whoosing. One way to diagnose is crack the two back windows about 1/4"-1/2" then drive it and see if it still does it. If it doesn't, it's the pressure relief valve. Oppps...just realized you must have a SUT. Don't know where it's located on the SUT but it's there somewhere.

[LasVegas]

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[Hummertech]

Is this happening while driving with the a/c on for a while? The reason I ask, is we have seen where after driving for a while with a/c on, the evaporator will actually form a layer of ice on it, when the ice forms, no air flow. Then it will start to melt and the airflow comes back. Solution for this is an updated deisgn a/c cycling switch.

[TXSUT]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LasVegas:
At the rear of your H2 behind the applique trim on the drivers side is a ventilation pressure relief valve. If it is sticking, it will appear that your a/c blower is surging. What you describe sounds like it is building excess pressue, then releasing. When that happens you'll feel/hear a whoosing. One way to diagnose is crack the two back windows about 1/4"-1/2" then drive it and see if it still does it. If it doesn't, it's the pressure relief valve. Oppps...just realized you must have a SUT. Don't know where it's located on the SUT but it's there somewhere. </div></BLOCKQUOTE>

For a minute there, I thought you were just yanking my chain about a pressure release valve. I was thinking, "this ain't no damn airplane." LOL! Thank you very much for the info; very helpful and makes a lot of sense given the nature of this issue.

-Pete

[TXSUT]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Hummertech:
Is this happening while driving with the a/c on for a while? The reason I ask, is we have seen where after driving for a while with a/c on, the evaporator will actually form a layer of ice on it, when the ice forms, no air flow. Then it will start to melt and the airflow comes back. Solution for this is an updated deisgn a/c cycling switch. </div></BLOCKQUOTE>

I know the dealership replaced the switch as part of the repair to address the cooling issue I had, and this problem happens right away after start-up.

Thanks for chiming in, very helpful info to have!

-Pete

[VTSTOMPER]

Does it do it with the rear window down a hair?

[LasVegas]

TXSUT...If this is happening right after startup I doubt it's the evaporator coil icing over. So I think it will have to come down to two possibilities: 1) The pressure relief valve 2) Electrical problems with the blower motor/controls. Eliminate the first possibility by simple cracking a window. Again, if that solves the problem it's the PRV.

[HUMMERcustoms.com/TAZ]

Jonahs last summer I was in Dallas and AC running. I walked around back and a friend felt cold air coming out from the right upper vent. I knew of there was supposed to be a valve on left. I have not taken it apart as it did not matter but, now curious does the 2005 have it in different location or maybe more than one. I have not felt on the left vent up high. I will check that when My Baby gets back from graphic shop Friday. I was just curious after reading these posts.
Thanks
TAZ

[LasVegas]

TAZ....it's suppose to be on the left side on '03 & I have no reason to believe it's any different on an '05. But you know how that goes. It might be on the right side of some/all of them. I've never taken mine apart so I can't confirm but it's there. I'm sure it only has one. Really don't know where it's at on a SUT.

[TXSUT]

Well, it must not be the PRV; still doing it with the window cracked. Back to the dealer...

[LasVegas]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TXSUT:
Well, it must not be the PRV; still doing it with the window cracked. Back to the dealer... </div></BLOCKQUOTE>Yes I think you're right. There's a "blower motor control processor" that may well be the problem but it's nothing you want to get into. Sorry couldn't pin it down. Hate those trips to dealers.

[TXSUT]

But thanks a ton, you've helped tremendously.