Problem With Defroster/air Conditioner?

Z71Silverado · October 26, 2011

Hey. I know driving with the air on decreases horsepower but does driving with the defroster on also decrease horsepower? i thinki will have an eventual problem. when the air conditioner is on there is a noise that sounds like a snake hissing when it's running, the same noise also happens when i turned the defroster on. There is a huge difference in get up and go with either the air or defrost on. is that normal? what could be making that noise? the air compressor?

dewfpo · October 26, 2011

Yes it's normal. In DEFROST mode the air conditioning compressor comes on to dehumidify the air and clear the windshield faster.

DEWFPO

Z71Silverado · October 26, 2011

Is there a way to set up the truck so that the compressor doesn't kick on with the defroster? I only use the defroster when it's cold so I see no reason for compressor to kick on.

txab · October 26, 2011

By running the compressor you're accomplishing at least 2 things:

1. Removing moisture from the air which aids in defrosting.

2. Allows seals in the AC system to be lubricated by the circulation of refrigerant and oil

Z71Silverado · October 26, 2011

Well what do you guys think the hissing sound is? it only happens when i turn the air or defrost on.

Patch6713 · October 26, 2011

Well what do you guys think the hissing sound is? it only happens when i turn the air or defrost on.

I also have had the same noise. I don't think it is coming from the compressor, I think it is coming from the drier? near the firewall.

Z71Silverado · October 26, 2011

Well what do you guys think the hissing sound is? it only happens when i turn the air or defrost on.

I also have had the same noise. I don't think it is coming from the compressor, I think it is coming from the drier? near the firewall.

what was the problem? and what did you do to fix it?

Z71Silverado · October 26, 2011

Patch6713 · October 26, 2011

Well what do you guys think the hissing sound is? it only happens when i turn the air or defrost on.

I also have had the same noise. I don't think it is coming from the compressor, I think it is coming from the drier? near the firewall.

what was the problem? and what did you do to fix it?

I haven't done anything yet. Been waiting to see if anybody else has been having the same problem and seeing what they do. Since the A/C and heat still work and since my local mechanic (doesn't do A/C work but I believe knows his stuff) said there is nothing there that can do any damage he said to leave it. Since it hasn't bothered me lately I haven't really looked anymore into getting it fixed. However, in my case it got worse when I had my snowplow on and since we are getting into that season I might end up being bothered by it enough to get it worked on.

mxeightyeight · October 26, 2011

My truck has made that hissing noise from day 1. It will only do it on lower fan settings like 1 or 2. I don't really worry about it. My father-in-law has a 2001 and his does not make that noise. Strange.

1990ss · October 27, 2011

I have the same noise on my '06. My '00, '01, or '02 didn't do it though.

u118224 · October 27, 2011

I also have the hissing noise on my '04 Suburban. It's been that way since I bought it.

mxeightyeight · October 29, 2011

Anybody have any idea as to what that noise is or where it is coming from? Not concerned about it but just one of those things I would like to know. Thanks