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GMC Yukon AC and Heat Questions



  • I have an 02 Yukon with a host of heating and A/C problems. I don't know if they're related, so I'll start from the begining.
    I started hearing a rattling noise from the engine compartment every time I turned on the A/C, which subsided after driving. Around that time, it was blowing hot air in the rear compartment. Then I began to hear the rattling even with heat/defroster. Finally, I'm getting hot air from the front. I checked the fuses and all appear good.
    Any advice/help would be appreciated.
  • jpw5jpw5 Posts: 1
    I have a 2007 Yukon Denali that is blowing warm air on the driver's side when temperature is at 60 degrees, (as low as it goes). It will occasionally "kick in" and blow cold air. It blows the normal cold air on the passenger's side all the time. I've taken it to dealer three times now and they can't figure out the problem. The first time to the dealer, they added freon. The second time, they replaced the actuator. The third time, they said they couldn't duplicate the problem and don't know what to tell me. It's still blowing warm to very warm air. This is very frustrating since I live in Texas. It's hot! Don't have time to run to dealership when hot air kicks in. I think they should have a way to troubleshoot this problem without having to "duplicate it" as they tell me. Any suggestions?
    Thanks. Also, don't know if this matters. The battery went totally dead and was replaced approximately eight months after I took delivery of the car.
  • 2007 Yukon. Bought at Texan GMC in Humble. I have had several problems with my AC system. Like the problem you describe, I have experienced problems with the AC kicking in/out. No rhyme or reason. Please let me know if you have found a solution to your problem....dealership has proven less than helpful. Seems unreasonable to have these problems in a $40,000 vehicle.
  • I am also experiencing this same problem on my 07, with the dealerships lack of knowledge and attempt to just throw parts at it with no success. My theory is a mixing door is stuck for some reason as it will get hot when you run the temp up, but will not get cold when you run the temp down. It only is on the drivers side. I am going back to the dealership tomorrow for the third time. The next visit I may be tempted to drive it through their wall and give it back to them.
  • Within the past 3 weeks have noticed a new glitch. When running the a/c it will sometimes blow hot air out of the front as well as rear a/c vents (it has dual a/c). I reading of other peoples issues, it seems like on their vehicles it's just the drivers side that does this. On mine, its left, right and rear. I've replaced the fuse and relay in the underhood fuse box, but the same symptoms exist. I've cycled thru the temp range thinking it's maybe a piece of crud in the mixing box jamming one of the doors, but that doesn't do anything. But if I turn the vehicle off for alittle while and start it back up and turn the a/c backon it works just fine. HOWEVER, (this is the weird part) the air is 5 degrees cooler than it's ever run before. On the day I baught it it put out 55 degree air and it's been that way ever since. I just chalked it up to "just the way it is". But now, when running properly, it puts our 48 degree air. I took it to our local auto air conditioner center and they couldn't find out anything wrong. They were unable to duplicate the issue and said that 48 degrees was supposed to be the norm, and they said that it was probably a bad mixing box and when I got good and tired of it flaking out for me to come on back and they'd replace it. He said that it was a [non-permissible content removed] of an item to repair. After I left, I got to thinking, if hot air came out of the front because of a bad mixing box door issue, why was hot air coming our of the rear vents too. It has it's own mixing box. Just today if was flaking out again and I decided to see what the internet has to say about this anomoly. Other than this single issue and a replaced water pump I've had zero problems with my Yukon XL. I must be one of the lucky ones that picked one that wasn't a lemon.

    If any of you have any insight as to what migh be my problem I'm all ears (eyes).

  • You never said if the compressor is running when the hot air is blowing?? Also, there is a switch for low freon on the silver canister for the air conditioning on the right side under the hood. You can pull off the wire connector and jump it with another wire to see if it is sensing low freon and not allowing the system to work. How many miles?
  • Sounds like your compressor is gone, or at least the clutch that kicks it in and out.
  • jlflemmonsjlflemmons Posts: 2,240
    Under the hood, pull the A/C fuse and wait about 10 minutes. Put it back in and start the car, put the A/C in the 'auto' mode. It will act a bit weird for a few minutes, then it should straighten out. This is the exact same scenario I went through when replacing the battery on my '04. Pulling the fuse forces the ventilation computer into a hard reset and self learn mode. Haven't had a problem one since doing this a month ago.
  • My heat has not worked for several months now, but with cold weather coming I need to get it fixed. A/C works fine for cooling when weather is hot.

    I recently had a new water pump and t-stat installed as part of a non-related repair, but no-heat problem was not solved. Operating temps seem to be within normal parameters. Water supply line to heater core is very hot, return line is ice cold. Possible plugged inlet to heater core? Seems possible, but not probable. Somebody suggested that I look at the actuator(???). Any other suggestions?
  • Hi my name is Andrea,
    My Yukon is doing the same thing. I was wondering did you ever get your fixed and if so what was the problem. Please inform me because I have not had my Yukon for 4 months and the dealer is about to get it all.
  • rayb6rayb6 Posts: 1
    Picked up vehicle last Sunday with 300 miles on it. When I restart my 2007 Yukon xl (Not Denali), my heat only comes on after I change the heat settings a few times. The temp gauge is up to near 210 but no heat. I have to adjust the flow direction. Went to the dealer yesterday and they said it was normal. Any suggestions would be helpful.
  • jlflemmons-

    Thanks for the great tip! I recently replace my battery on my '04. Well, when heater is turn on the passenger side blows Hot air but, the driver side blows Cold air; "very cold".

    I called the dealer and they didn't have a clue but wanted to keep my GMC for a few days.

    I think your reprogramming will reset the system. . .thanks --Los Angeles, CA
  • Mine is a little different than everyone elses. when it's cold out.. say in the 20-30s it takes forever for the defrost to start blowing... either hot or cold...

    in the summer sometimes it takes mins. before the a/c will blow....

    no problems with air temp.. just the time lag for it to blow any air at all...

    anyone have a clue?
  • This sounds kind of like my problem with the 01. Due you have the auto climate control? Does the rear blower work, even if the front one does not? Let me know this, and if this is the case, I might be able to help you.
    Lyle Pfeifer
  • yes.... rear works as designed and the front is the only one that gives me problems. it has auto and i'm tried the fuse reset... maybe i'll try it again just longer.

    ok this morning it was cool 45degrees and it took awhile to come on. now it's 65 and it will turn on real quick... if it's 100 the a/c will take awhile to blow

    but rear air is normal in all aspects
  • :cry: come on now?????? nobody has any ideas?????
  • tidestertidester Posts: 10,110
    Maybe the fan is "gummed up?"

    tidester, host
    SUVs and Smart Shopper
  • not sure... it works and works well.. but, it has to finally decide to turn on and once it has been going for awhile it will turn on instantly.
  • Do you have dual air/heat?
  • There is a plug that goes into the AC/heater fan. You have to remove a cover that is held on with 3 or 4 screws and you can see the fan motor. This cover goes from the passenger side all the way to the middle of the tunnel. The plug is on the right or inside of the fan and kind of hard to get to and remove. The fan is located on the passenger side of the car, the plug, if like mine is shorting out. It is connected to a box or block, similar to the resistor block on a non auto climate control unit. Yours runs about $130.00. I replaced mine as the plug melted due to being installed wrong. Look inside the plug for bunt contacts. One of mine, the main power point was pushed all the way down and did not spring back up to allow good contact, causing a high resistance and heat build up causing the plug to melt. If you pound on the cover about 1 foot over from the passenger side wall with your hand, your fan should start. But remember, this plug is getting hot. This is at least what happened to mine. Worse case, if you need a new plug, you have to buy the harness just to get the plug, I think they said about $165.00.
    Hope this helps. Let me know, as I had this problem with a 2001.
    Lyle Pfeifer
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