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Ac Not Working

Tage

By Tage
in Ask A GM Technician

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Tage Enthusiast

Tage

Posted
Posted

I bought a 2003 Yukon XL Denali and the AC is not working. I thought this would be a no brainer for a fix as the compressor was making some god aweful noises with the belt connected (so I removed it). Yesterday I put a brand new compressor and belt in and filled it up with approximately 28oz of freon. When I turn the AC on, the compressor/clutch does not engage and the little picture of the snowflake on the display has a line through it which I'm assuming is saying, "hey dummy, there's no AC!".

 

There was a few fuses in the side of the dash on the driver side door as well as a few fuses under the hood. All of those fuses were good. I also found an AC relay which I swapped with the horn relay. The horn still works but still no AC. I haven't checked the plug to make sure voltage is going to the compressor yet as I wanted to ask here making sure I'm not missing something simply like, "you have to use a OBD-II scan tool to enable the AC" or something along those lines.

 

NOTE: I did not replace the expansion valve thing or dryer. While not optimal I wouldn't think those items would keep the AC compressor from at least kicking on. Maybe severe blockage causing the freon to not flow and compressor to not engage???

minibike132 Senior Enthusiast

minibike132

Posted
Posted

Before we get all technical, what is the temperature there. The A\C is inhibited below a certian temp. I don't remember the inhibit temp off hand.

2000DV4.8 Senior Enthusiast

2000DV4.8

Posted
Posted
Before we get all technical, what is the temperature there. The A\C is inhibited below a certian temp. I don't remember the inhibit temp off hand.

 

 

Durn it, ya beat me to it... :rant:

Tage Enthusiast

Tage

Posted
  • Author
Posted

It was in the 70's yesterday when I tried it. My other Yukon with working AC never has that little line through the snowflake, even in the dead of winter and I turn the AC on. Although in Phoenix, AZ it rarely goes below freezing. I suppose I forget that most the country is experiencing winter right now...

 

A few days ago it was 85 degrees and this vehicle is the family hauler so the wife and kids are going to be pissed if this isn't fixed in the next day or two. Hopefully, it's something simple I can do, otherwise I'll be taking it to a shop (or dealership) this week.

bobcat5544 Enthusiast

bobcat5544

Posted
Posted

1st. After you replaced the compresor did you have the ac system vaccumed down or did you just add freon after you replaced the compressor?

 

2nd, If the compressor you replace had a internal failure and you did not replace the expansion then you have metal clogging up the expansion valve. you will need to replace expansion valve, the dryer, and flush the rest of the system to get all the metal out.

Tage Enthusiast

Tage

Posted
  • Author
Posted

I went ultra ghetto on my install. I just slapped the new compressor on and filled it up with freon. I know that you're "suppose" to vacuum it down but I wanted to at least see if the compressor would kick on which it didn't.

 

I didn't even think that with an internal compressor failure there could be bits of metal in the system causing blockage. This is starting to get outside of my area of expertise and confidence level so it sounds like a trip to an AC shop is in my near future...

 

Thx for the advice!

  • 2 months later...
yukonsurf New Member

yukonsurf

Posted
Posted

Have the same issue. Intermittently ac gets cold...usually on the lower fan speeds, then just goes away when it wants to. Replaced the Low -pressure switch with a new one....same damn thing cost me $55. Any suggestions? 04 Yukon 50k miles all original a/c components. WTF?

 

Also, the control unit back lights are out. Anyone know which color wire is for the backlights, I think it is a loose connection on the pin in rear of the unit as it flickers on and of when jostled.

 

Thanks!

hubbycap Senior Enthusiast

hubbycap

Posted
Posted
Have the same issue. Intermittently ac gets cold...usually on the lower fan speeds, then just goes away when it wants to. Replaced the Low -pressure switch with a new one....same damn thing cost me $55. Any suggestions? 04 Yukon 50k miles all original a/c components. WTF?

 

Also, the control unit back lights are out. Anyone know which color wire is for the backlights, I think it is a loose connection on the pin in rear of the unit as it flickers on and of when jostled.

 

Thanks!

 

If it cools real good then goes away . . . maybe compressor clutch.

thebosss83 New Member

thebosss83

Posted
Posted

My A/C wont kick in until I get moving, i.e. 15mph +. When I start the car and let it idle, no matter how long, the A/C will not cool down and blow cold. Any ideas? 2004 GMC Yukon XL Denali w/ 80k

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