a/c noise

lego96 · July 17, 2005

I took my 05 silverado 1500 ls off the lot today.

a/c makes a raspy sound like you can hear the liquid rattling in the condenser under the dash. Any thoughts on the problem?

Thanks

GM-Tech · July 17, 2005

Actually, the condenser is in front of the radiator. It's the evaporator that's under the dash, but I know what you mean.

Normal. Here's some info on it...

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03-05 Chevrolet/GMC/Cadillac All Full Size Trucks and Utilities Hiss Noise from Dash with AC On - kw HVAC idle blower compressor line hose #PIT3344 - (Jan 4, 2005).

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:

Customers may comment of a hiss noise coming from the dash area with the A/C on. The noise can come and go or change intensity depending on A/C system loads (outside temp, engine RPMs, humidity, etc.)

Recommendation/Instructions:

The noise is normally only heard while stopped with blower on low and radio off. The noise is coming from the A/C orifice tube and is normal. No repairs should be made.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Models:

(03-05 Chevrolet All Full Size Trucks and Utilities) and (03-05 GMC All Full Size Trucks and Utilities) and (03-04 Cadillac All Full Size Utilities)

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

polarisboy · September 27, 2005

I think I might have a similar problem with my 05 HD2500. Whenever the compressor cycles, either in A/C or defrost, I can hear this "purring" sound, much like fluid flowing through the evaporator core, as described previously.

Additionally, my truck exhibits a whistling sound through the dash vents when in the A/C mode, when the compressor cycles. This is addressed by ASI bulletin

04-01-38-014. Why no one is addressing this is beyond me.

GM-Tech, the data you gave in your response lists "Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed."

What are the steps? Are they defined in the bulletin and you just didn't list them?

I am VERY interested in attempting to fix my truck. I have worked with Customer Service with no success. They don't care about fixing it. Frankly, the whislting noise drives me crazy. But it only occurs when the ambient temp is 80 or more, and is worse with higher engine speed and outside temps.

Can you PLEASE HELP??

GM-Tech · September 27, 2005

Additionally, my truck exhibits a whistling sound through the dash vents when in the A/C mode, when the compressor cycles. This is addressed by ASI bulletin
04-01-38-014. Why no one is addressing this is beyond me.

No one is addressing it because this bulletin says, "there is no fix at this time. Record the customer info so the customer can be notified when a fix becomes available" or a statement to that effect.

GM-Tech, the data you gave in your response lists "Please follow this diagnosis process thoroughly and complete each step.

PI's (preliminary information) bulletins all have this text. It's a standard statement at the end of all PI's. They all say that, whether there are steps or it's information only with no actual repair information.

Incidentally, my Colorado does the same thing. There's a fix for those and it's to replace the evaporator. It doesn't bother me and I'm not tearing the whole dash out to fix a slight whistle that occurs for about 1 second every once in a while.

GM-Tech · September 27, 2005

Here's some new info, just came out last week...

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Hiss Noise from Dash with AC On - keywords air blower compressor conditioner hose HVAC idle #PIT3344A - (Sep 21, 2005)

2003-2006 Cadillac Escalade, Escalade ESV, Escalade EXT

2003-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe

2003-2006 GMC Sierra, Sierra Denali, Yukon, Yukon Denali, Yukon XL, Yukon Denali XL

except if equipped with RPO LB7 or LLY

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Customers may comment of a hiss noise coming from the dash area with the AC on. The noise can come and go or change intensity depending on AC system loads (outside temp, engine RPMs, humidity, etc.). The noise is normally only heard while stopped with blower on low and radio off.

Recommendation/Instructions:

The noise is coming from the AC orifice tube. To correct this concern change the tube assembly between the condenser and the front of dash or evaporator. The new tube assembly to add is as follows:

Part Number

Description

15785056

All Full Size Trucks and Utilities without rear auxiliary A/C

15785057

All Full Size 1500 Utilities with rear auxiliary A/C

15785055

All Full Size 2500 Utilities with rear auxiliary A/C

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

polarisboy · September 28, 2005

Incidentally, my Colorado does the same thing. There's a fix for those and it's to replace the evaporator. It doesn't bother me and I'm not tearing the whole dash out to fix a slight whistle that occurs for about 1 second every once in a while.

<{POST_SNAPBACK}>

I wish my truck only did it for 1 second every once in awhile. It does it for 2-3 seconds every time the compressor cycles!

Thanks for the info, I'll take it with me to the dealer and see if they will at least try it on my truck.

Thanks,

Mark

GM-Tech · September 28, 2005

I wish my truck only did it for 1 second every once in awhile. It does it for 2-3 seconds every time the compressor cycles!

Thanks for the info, I'll take it with me to the dealer and see if they will at least try it on my truck.

The fix posted is not for the whistiling.

lego96 · October 6, 2005

The repair shop at Mac Haik chevrolet in houston says this fix will ruin the cooling efficiency and will never be the same. They recommend to skip the fix and live with it.