Automotive Air Conditioning Information Forum (Archives)

sonikdreem on Thu July 22, 2010 11:19 AM

Year: 2002
Make: GMC
Model: Sierra c/k 1500
Engine Size: 5.3

I know nothing about mechanics...just need some advice. I cannot afford to not get this fixed correctly the first time.

My truck was making a knocking last year when the ac was on recirc (lower passenger side, sounded like a fan blade hitting something...in time with the rpm), but the ac was blowing cold though not as hard as it did when I bought it. The kocking would appear mostly when I accelerated. This got progressevely worse but never affected the way the ac was blowing. It did start to cause the engine to drag when the noise occurred. Then the noise started to happen even at idle and even when the ac was set to fresh air vent. My parents paid a friend to work on it. He recharged the ac, replaced a small part (not sure what it was)...kept saying he thought he knew what it was, but oh it must be something else...kept charging my parents and never fixed it. Winter came and I didn't need ac anymore. This summer came and finally the ac just stopped blowing cold and the knocking is gone....no draw on the engines power anymore...but the air is blowing.

What is going on? I need AC

Peter

HVargas on Thu July 22, 2010 11:23 AM

Sounds like the system is too low to engage. Check and see if the compressor kicks on when you are turning on the A/C in the truck. If you don't really have any mechanic knowledge, your best bet may be to take it to a professional and have them reclaim what refrigerant is left and pull the orifice tube. I would venture a guess that it is pretty full of debris based on the knocking noise.

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Cussboy on Thu July 22, 2010 2:41 PM

My Suburban (1994) had similar knocking sound under the dash, passenger side, and it was the motorized diverter door motor for Recirculation or Vent, the grear went bad. I had it replaced.

Edited: Thu July 22, 2010 at 2:41 PM by Cussboy