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GMC Yukon AC and Heat Questions

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  • I just bought a 2004 Tahoe for my wife, we could start her car and let it idle forever with no heat. Anti-freeze level appeared correct in resavoir, added 1- 1/2 gallons of anti-freeze and Bingo, now heat will drive you out of car........
    Thanx for the tip..........
  • arriearrie Posts: 312
    So,

    You have a leak!

    You probably have the porous cylinder head cast problem that lets engine coolant to leak internally inside the engine.

    I would get BAR's radiator leak fix and pour it in the coolant expansion reservoir. You really need to do something and this is the cheapest fix that I know that at least worked for me.

    Arrie
  • arriearrie Posts: 312
    Little SCARY info for all readers with possible coolant leak.

    A couple of days ago I went to check on the coolant level on my '04 Tahoe engine. I have posted before that after using Bar's radiator fix I stopped loosing coolant as when I look at level in the reservoir it has not gone down.

    THIS WAS ALL WRONG! I STILL HAVE LOST COOLANT BUT LEVEL DID NOT GO DOWN IN THE RESERVOIR !!!!!!!!!!!!!!!!!

    What I did was that while engine was running I opened the cap of the coolant reservoir and the level went down by 1 1/2" immediately when I broke the seal of the cap.

    I did not have any steam come out from engine to the reservoir so I was not overheating or nothing like that but the engine definitely was not full of coolant in all cooling channels.

    THIS IS VERY SCARY AS WITHOUT OPENING THE CAP OF THE COOLANT RESERVOIR YOU CANNOT SEE YOU ARE LOOSING COOLANT!

    What probably causes this is a very poor design of the reservoir and its connection in cooling system. It probably is that too small tubing from the reservoir does not allow coolant level in the reservoir go down because the reservoir is sealed, i.e. cannot get air in for the coolant to flow out. The valve in the cap does not let air to flow in the reservoir, only excessive pressure out from it.

    MY SUGGESTION TO ALL READERS WITH SIMILAR ENGINES (5.3 L) AROUND '03 - '06 YEAR MODEL DO THE CHECK, I.E. OPEN THE RESERVOIR CAP (BEING VERY CAREFUL) WHILE ENGINE IS IDLING AND SEE IF LEVEL DROPS DOWN.

    I think I will disable the valve in the reservoir cap, i.e. make it so that reservoir can breath freely in and out. Perhaps there is a check valve that could be installed on the cap that would let air freely in but outgoing pressure would still need to work thru the valve in the cap.

    Arrie
  • ok, the blower still works,but the vent selection knob will not change where the air flows and the a/c snowflake light button does not turn on the a/c.when you hit the button to turn on a/c it feels like the vent just pulling in outside air.The recycle but also does not come on to recycle the cabin air.I have checked all fuses ,they are all good.all levels of the blower switch works,just not the position select switch or the buttons.please help!
  • (1) Two months ago, the front AC only blew on "5", not 1 through 4. The rear AC works fine. Is it a switch issue!?

    (2) Went out to the truck today and the AC blower was running when the truck was off, keys in hand?!?!

    (3) I took out a 10 amp AC fuse and killed the front AC. Rear still works great.

    What are your comments with regard to these three issues?
  • 2000 tahoe 5.7 old body style. Blower fan just quit the other day. Have checked fan by straight wiring to 12 volts, it works. Replaced resistor and relay behind glovebox. Checked all fuses. Don't know where to turn now.
  • jking5jking5 Posts: 2
    When the AC on my 2004 Yukon XL is running, sometimes the heat comes on...just on one side, while cool AC continues to blow from the other side? Any suggestions besides taking it to the dealer's. Warranty has run out and can't afford their rates.
  • arriearrie Posts: 312
    I have posted about this before a couple of times. I had the same problem with my '04 tahoe and I fixed it by disconnecting the A/C control unit wire harnesses.

    Easy job to do. Take the bezel out and unscrew the 4 screws. You need to hold the clips on both sides to pull the controller out. Disconnect harnesses at the same time and then replace all.

    Worked for me.

    Arrie
  • Thanks for the help. Pretty straight forward job except for disconnecting wiring harnesses. Not a lot of room to work with. Blower is working fine at the moment.
  • nana15nana15 Posts: 1
    I have a 97 yukon, the rear cool air stopped working and the front does not seem to blow that cold. I have had coolant put in and it checks fine.The rear just blows hot air,it is ac only in the back. Can someone help?
  • Problem:

    My rear A/C blows really cold regularly and the front blows cool for only a couple of days after a couple cans of 134A.

    Question:

    Is there a leak? Are my valves clogged? Or does something need to be replaced?

    Any advice would be greatly appreciated!

    Thanks,

    Coach
  • All I can say is A-W-E-S-O-M-E!!!!!!!!!!!! My son has a 2004 GMC Yukon and first it had a short in it that was draining the battery. I got that fixed. Then the speedometer cluster went out. $600 at GM to fix it, but I found a guy on E-Bay that fixed it for $64. (Brian's Speedometer Shop-Muldrow, OK) Now the AC was blowing hot air out the driver's side and cold air on the passenger's side. I just went out and took it apart and unplugged the harnesses on the back of the AC control and it works GREAT! Thank you very much! :)
  • jking5jking5 Posts: 2
    Is this something so simple a layman can do it? I'm not sure I'd know what a harness is?
  • here's the problem.
    my a/c work's fine until it gets hot out side and the inside of the suv gets hot.
    Then the a/c wont get cold. It works on not so hot day's.
    help me. Im going to the Mojave desert next week.
  • arriearrie Posts: 312
    From what you say it sounds like your A/C system refrigerant charge is low.

    To check for this you would need to have refrigerant pressure checked. Normally this is easy by running the engine with A/C on MAX cool and check the pressure in the low side service port but as your truck is 1994 model it could be more complicated as you might still have the old R12 refrigerant system. I'm not sure if pressure gauges etc. are available for that system to buy without a permit.

    If you have the R12 system you should have it converted to 134a system, which you can service yourself.

    If you have the 134a system get a pressure gauge from a parts store. Check pressure and if low charge system but first add oil charge as it is an old system. You might also want to add a charge with O-ring conditioner as if you are low in charge then you must have a leak somewhere.

    Add refrigerant until pressure is at required level.

    Arrie
  • I am new here; I have been reading up on climate control issues after battery reconnect. I have tried removing Neg batt terminal to reset; would next like to try to reset module by pulling fuses. There are several that refer to front, both under hood, and on side of dashboard. Does anyone know the exact fuse that I should pull to attempt this reset. My system is blowing heat only, and I have no control over where the heat exits. Rear air is just fine.
  • Yesterday I purchase and had installed 4 new tires, had an alignment,and a complete brake job done on my 2005 z71 suburban; it was like driving a new vehicle. Shortly after I hit the road from NTB I put on the air conditioning and noticed that I had cool air conditioned air on the driver side and heat from the passenger side. Does anyone have any advice? Could the air pressure sensors in the wheels effect the electrical system and confuse climate control? Are there any components that the service tech could have messed with?
  • jbastjbast Posts: 1
    mcdaddy,

    I was wondering if this fix is still working for you. I'm about to buy an '04 yukon in phoenix and a/c is super critical. I experienced this prob on a test drive yesterday. was gone after a restart but won't always be able to pull over. If good, can you give me some clues on harness/colors so I pull the right one??...

    thanks,

    Joe
  • Finally solved my a/c problem; tried a several things, like removing battery terminals and holding them together to drain residual voltage from processor, etc. Ended up that after removing neg terminal and putting it back in place, I turned on key, BUT DID NOT START THE YUKON. Waited a couple of minutes to let it re-program itself, then started it up. At that point, all is well. Hope this helps!!
  • tidestertidester Posts: 10,110
    I am glad that worked out for you and thanks for sharing.

    One minor point, however, you did not remove the battery terminals. You removed the battery cables. That's just so no one tries something dangerous. :)

    tidester, host
    SUVs and Smart Shopper
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