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GMC Jimmy Heating and Air Conditioning Problems

drogersgolfdrogersgolf Member Posts: 2
edited September 2018 in GMC
My jimmy just started blowing cold air at idle and slower speeds, but when I get up to higher speeds (50mph) or more it blows warm or hot air. I also noticed that my 4 wheel drive don't work either, not sure if these problems are related.

Clueless and not a mechanic,

Donnie
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Comments

  • rpducros2rpducros2 Member Posts: 3
    Any problems with your A/C ... talk about it here.
  • rpducros2rpducros2 Member Posts: 3
    Ok here is my problem. Its going to sound very strange. A/C works decently at night. blows around 60F. During the day im lucky to get 65F. The strange thing is, The higher the fan speed ... the hotter it blows. the lower the fan speed the cooler it blows. I checked the compressor levels, i have everything in the green on both high and low side. All my pipes going to and from compressor/accumulator are cold and sweating. Anybody have any ideas ? Could my A/C be sucking hot air from somewhere ? IM totally stumped. Any ideas are welcomed.
  • jglongjglong Member Posts: 1
    My '03 Trailblazer constantly reads inaccurate actual outside temperature. For example, here in Oklahoma we've had 30+ days of 100 degrees or higher, but my Trailblazer never reads more than 50 degrees. Consequently, my A/C sucks.

    What do I need to replace/check?
  • repairdogrepairdog Member Posts: 948
    Never said year but yes the recirc door could be stuck or actuator bad. If you have climate control there is also a blend door - with AC problems I go to the shop after checking connectors - too many interlated problems. But also check the vac hoses under hood on drivers side for rot - the lower one Ts off )plastic one) to the AC.
  • repairdogrepairdog Member Posts: 948
    There is a temp thermistor believe up by the radiator (is on Blazers) that feeds the readout and if bad or way out of cal will screw the AC up.
  • il203il203 Member Posts: 3
    My 2000 Jimmy (97K miles) heat does not work. Only ambient temp air blows out. A/C works fine. Checked temps on all Radiator hoses and hoses going in and out through fire wall. Temps from 130 - 200 degrees. Thus, some heat should come out. Checked with vacuum gage that the all vent doors worked. No apparent problems. Pulled front dash off and can see the blender door motor pin rotates when the temperature adjuster is turned from hot to cold and back. No change in air temp though. The amount of air flow does decrease when changing temp knob from cold to hot. Thought is the blender door is stuck or broken. However, getting to the blender motor looks like a challenge. Any advice on what the problem may be and what to do next.
  • georgetowngeorgetown Member Posts: 1
    I have a problem with my Jimmy. When I turn on my ac the ac compressor turns on but there is no air coming out of the vents. Sometimes the air will blow for the first 3 minutes when I turn on the ac but it will always turn back off and I can still here the compressor on. Anybody heard of this before?
  • repairdogrepairdog Member Posts: 948
    Sorry, sounds like the classic clogged heater core so no water flowing thru it - have to flush and hope it doesn't leak or blow a hole - another Blazer defect, oh did I say that - Dex cool should be flushed evetry 3 years min and any air in the system it gels up. Search on clogged heater core and I've posted the flush several times. Good luck cause the heater core is dash out and over $500. No help after 5/75 or so by GM but if before for others they pay half if you ask for zone to review.
  • repairdogrepairdog Member Posts: 948
    Take it an AC shop and have them look at the R134 level, could be low, the pressure switch bad, or a loose connector. Not easy without AC gauges to find. If 97 and over 80-90k miles the compressors blow the front seals, another GM quality part so get a NEW compressor, not rebuilt or it will die within a year.
  • e5husmce5husmc Member Posts: 6
    Last spring the A/C was only putting out a little cool air so I bought a can of R134 w/leak detector and everything was fine. This fall after using the heater for a couple of weeks the weather got warm again, A/C isn't cold again. Put in another can of R134 w/leak detector, cleaned around hose connections and compressor, no leaks found. Stayed cool until we used the heater again. Anyone have any ideas?
    :confuse:
  • breedenbreeden Member Posts: 3
    Something is very wrong with my 98 Jimmy's climate control. It keeps going back and forth between hot and cold and it sounds like it is changing back and forth between recirculating and bringing in fresh air. Even when I turn the dial to off, it continues to make the sound like it is switching back and forth. Anybody have any ideas?
  • repairdogrepairdog Member Posts: 948
    If the auto climate system with temps on the dials then you have an additional electric blend motor that swings the heat air door to maintain the temp and it has a plastic gear that can get stripped and if your battery died recently can get lost or not know where it is so searches. Dealer can reprogram or replace and I suggest them as most other shops have not done these and it actually runs much more.
  • breedenbreeden Member Posts: 3
    Yeah, one of the battery terminals had worked lose just before it started happening. Thanks a bunch
  • bg3000bg3000 Member Posts: 1
    When I started my '95 Jimmy yesterday morning the heater fan was on and blowing, so I turned it off until the car could warm up. When I went to turn it on again the fan didn't come back on. No noise, no fan , no nothing. I checked the heater fuse and replaced it, but no luck. Any ideas?
  • repairdogrepairdog Member Posts: 948
    Probably the fan motor died - cheap part to replace from underhood and believe only 3 small bolts - all stores sell them. Also possible fan resistor mounted by AC box but thats speed control so fan should still be on at some speed.
  • mkcuraremkcurare Member Posts: 1
    My 2000 Jimmy stopped blowing air. I have heat and defrost, just no air movement. I'm not sure where the blower motor or blower motor resistor are located. On this model they seem to be hidden by a sealed black plastic shroud that must be cut open. Is the motor resistor located within that black plastic shroud or is it mounted somewhere on the firewall?

    Thanks in advance.
  • jnohrjnohr Member Posts: 2
    My 2001 Blazer just suffered the same fate. How do we get to the fan motor?
  • repairdogrepairdog Member Posts: 948
    Resistor is under that plastic cover - cut to access. The fab motor is accessed underhood on pass side.
  • mkobmkob Member Posts: 10
    I have a 99 GMC Jimmy with 122k miles, this vehicle has never had a/c problems up until 2 days ago. Our temp outside is 96 and when I went to use my a/c it blows warm air. I checked the charge and it is fine, all hoses are in great condition and fan is working. I kept running the a/c trying to figure out what the issue was and finally after 17 minutes the cool - not cold air came out. What could be the reason?
  • repairdogrepairdog Member Posts: 948
    Pressure switch problem or loose connector (check one on rear of compressor under the air intake) or the comp is leaking or clutch is failing.
  • jlflemmonsjlflemmons Member Posts: 2,242
    Cheap trick on the pressure switch. If the compressor is not turning, not just the pulley, but the whole thing, disconnect the harness from the pressure switch and jumper the contacts in the harness with a paper clip. See if the compressor comes on, is quiet, and cools. If it does, probably a bad pressure switch.

    If it is really noisy, doesn't cool, and you are sure the freon is still in there, I am afraid you may have a worn out compressor. HOWEVER, on my '99 Blazer, the same thing happened and testing showed it was down on freon. Charge was added and a leak test performed. No leak, and two months later it is still working great. The ac guy had the right attitude. Instead of "you need a new compressor", he took the logical approach. "This sucker is eight years old. Some of the freon is going to leak out sooner or later. And this particular system doesn't have that much in it to begin with."

    I like a mechanic who can think logically. :)
  • tsg3313tsg3313 Member Posts: 7
    I have a 97 jimmy that the ac is not cold. The compressor comes on every 10 seconds or so because I see the clutch engage. I added about 1/2 can of r134a and checked for leak, and found none, any ideas?

    Thanks!
  • repairdogrepairdog Member Posts: 948
    Take it to an AC shop for a test and probably the pressure switch or a loose connector.
  • mkobmkob Member Posts: 10
    Thank you for the suggestion. I found it was a combination of putting a new belt tensioner on and adding more R134. Even though I did the test for the pressure and it showed I was fully charged I guess my tester was bad. Good news it was not expensive to fix and I did it myself.
  • jlflemmonsjlflemmons Member Posts: 2,242
    I love it when it works out right. My gauge showed my system to be fully charged also. It was a little over a half pound low, if I recall correctly.

    Now it will make ice cubes!
  • moldygmoldyg Member Posts: 4
    Hi there, i have a 2000 gmc jimmy and my heat stopped working the other day and now it seems my truck seems to be running hotter then normal. And ive been hearing this gurguling noise coming from the passenger side? just wondering if its my heater core or something else? thanks fo your help
  • jlflemmonsjlflemmons Member Posts: 2,242
    How many miles on the Jimmy, and have you ever had the coolant replaced? The gurgling you hear is coming from the heater core. There is air in the cooling system and that will cause the engine to overheat.
  • moldygmoldyg Member Posts: 4
    i have about 115,000 kms on it. Since ive owned it its never had the fluid replaced...ive owned it for 3 or 4 year
  • repairdogrepairdog Member Posts: 948
    You have a clogged heater core with the sound and lack of heat OR you are very low on coolant. Dex cool becomes sludge and if not maintained actually eats the core and radiator, clogs the factory cap, and the thermostat. Get that system completely flushed and refilled changing the cap and thermostat. I would first check the system for leaks with a free use pressure tester and see if after you pump it up to 16 lbs it drops and where. 4.3 is known to get lower intake gasket leaks by 100k miles so look carefully along the lower intake to block mating surface, at the water pump, and listen for the heater core hissing with the pressure test. Again - change that Dex cool every 3 years/50,000 miles at least - don't you wonder why the GM warranty expired at 3/36!
  • gin6gin6 Member Posts: 1
    This is my first post,Son has a 1999 Blazer that I bought used 2 yrs ago.After 1 mo.had the radiator flushed twice,I kept getting that overheating smell,but the shop said it was fine.My question is,Why keep useing the Dex Cool if it keeps cloging the radiator and causing slug?I know that there is green,orange&yellow coolant on the market(Very confusing for us 50+ hotrodders).Can we use another brand? Blazer finally quit on my son so we are now tearing into the engine,( head gasket has lrg. split and corrosion between cylinder)and I am having the heads checked for cracks.When we put it back together what coolant is best? Thanks for your input.
  • moldygmoldyg Member Posts: 4
    thanks for your help...i try the rad flush
  • repairdogrepairdog Member Posts: 948
    Well thats a loaded question. Once you clean the whole thing out (and change that leaking core if it is) then there are many articles on antifreeze out there. Dex cool hates air in the system and that 5/100 change from GM was crap. GM was on like thir 5th cap design and the 4.3 was the worst due to high heater core and tiny tubes. If teh Dex was not in the right mix there is a voltage diff that occurs and speeds the metal eating. Too much info - I'd use green after a full rebuild but read up on them online. I have 4 and still use Dex and keep them full and changed every 3/50 max. Put a new waterpump on at the same time cause it will soon go and at $55 for a new one- and a Stant cap and high quality thermostat. Make sure the tubes in the radiator are clean too or you will overheat that new motor -they are abput $150.
  • mkobmkob Member Posts: 10
    I had many issues with Dex Cool, I had it clog my heater core, cause my 99 Jimmy to overheat, didn't allow vents to work and cracked my intake valve. I had it removed and reversed flushed out of the system. Sad to say it was about 1000 to do, but I strongly feel I was ripped off because I am a woman and they don't think I know what they are talking about.

    I have had the normal coolant in the vehicle for a little over a year now and have had no issues at all. I have heard the Dex Cool will eventually eat away at all the hoses and some metal parts in the engine. I have no idea why Dex Cool is still being used and why it has not be recalled.
  • tsg3313tsg3313 Member Posts: 7
    where is the pressure switch and harness? and which side do I jumper? I diconnected the harness on the compresor and when jumped blew the ac fuse

    thanks
  • jlflemmonsjlflemmons Member Posts: 2,242
    I think you figured out that was the wrong harness! You shorted out the compressor clutch circuit. Put in a new fuse and hook that back to the compressor.

    Then, just in front of the passengers side firewall is a large aluminum cylinder with freon lines going to it. There will be a thing sticking out of the side of it with a connector plugged to it. This is the pressure switch. Disconnect the harness and jumper the contacts with a paper clip or such. This will tell the compressor that there is pressure in the system and keep the compressor clutch engaged. If that compressor starts really rattling or banging, pull the jumper out and find a good A/C shop. It could still be a low freon condition, but more likely a shot compressor.
  • repairdogrepairdog Member Posts: 948
    Just a note that the GM compressors usually go by 80-90k and rebuilts are not the way to go - good shops use only new compressors for these at $50 more max. They have had problems with hose pressure switches and also possible loose pins in the rear connector on compressor, but usally the rear seal goes and new comp time.
  • jlflemmonsjlflemmons Member Posts: 2,242
    "GM compressors usually go by 80-90k "

    Great. My '99 has 78K on it. :(
  • repairdogrepairdog Member Posts: 948
    Summers coming so guess its your time. 3 of my 4 went by then and the 4th has 95k and I'm on borrowed time so can already feel that $700 or so getting sucked out of my wallet.
  • jlflemmonsjlflemmons Member Posts: 2,242
    Well, we've already had some pretty warm days here, but it cools really well and doesn't make any noise.

    Does have an odd little rattle coming from somewhere at certain engine speeds, but not a/c related. Maybe cat?
  • repairdogrepairdog Member Posts: 948
    Could be the exhaust - most good muffler shops will put it on the lift and tap along the system to find the rattle - could be baffles in the muffler (most common), cat failing internal, mount bad, even the O2 sensors (heated so an external shield and I had one rattling) or its a 99 so you have the wonderful secondary air injection system with check valves on each exh manifold that rattle when they fall apart inside and the electric pump under the radiator that comes on for 1 min each start to blow air in to prefire that cat and those heated O2 sensors! Look that up I've posted several fixes on that.
  • sshaffersshaffer Member Posts: 5
    In Jan 07 I hit a deer that sent my 02 rendevouz into shock. Since, my front end was replaced as well as the radiator.I drove the car for a 5 days taped together by the body shop. On day 5 my heater ran cold if rpms were below 2,000, warm when driving at higher speeds, eventually overheating. Thermostat was repaced 3x's, water pump replaced, heater core and engine flushed. Each time I returned because of overheating or no heat.Odd that after each repair listed above the car would run fine for about a week.My mechanic was stumped after my second return. He also did the pressure test for the head gasket and said that it did not test abnormal. No leaks are detected and my antifreeze is at normal levels. Talking to him today because I am overheating again he is leaning toward the heater core. My Rendevouz has 65,000 miles on it. It's costing me an arm and a leg! I don't think it is the heater core. Can any one help?? :sick:
  • karenscarkarenscar Member Posts: 2
    Hi sshaffer, have you had any luck with this? I am having very similar problems with my 02 Civic. I have tried all of the things you mentioned INCLUDING had head gasket replaced and still have the same symtoms. I had the radiator replaced 2 weeks ago at Round 3. Immediately after that and for about a week the fluid level was at the correct min/max range, I was getting heat when idling, and no overheating. But 'something happened!' and now the antifreeze is above normal--almost to the top of the reservoir, and also now no heat when idling. I'm just waiting for the temp spikes to start again--this is exactly the same thing that happened x2 before following Round 1), water pump/timing belt replacement and then Round 2) head gasket. So, if anyone can help with this it would be most appreciated!
  • sshaffersshaffer Member Posts: 5
    So sorry to hear about your civic. The problem has not resolved, sorry to report. My car sat in the garage Wed- Fri. Then before I took it to my mechanic I made sure that the coolant was topped off. The reservoir took just under 1 gallon and the radiator about 1-2 cups. It was running fine at that time. I took it to my mechanic about 20 min on back roads. Ran beautifully, real heat,even idling. In the past my coolant levels were fine,according to my mechanic and my husband. Well this has me suspicious. Obviously, I'm slowly losing coolant. Maybe something as simple as a loose hose. The oil is clean. No white smoke. No drips,nothing on the ground. Mechanic said that it is going somewhere. Either the engine, on the ground or out the exhaust.So.....My husband had never heard of this.
    Sat am I finally broke down and took it to the dealership. It will be looked at Monday 4/16. I'll keep you posted.
    By the by....I subsequently [ut the same scenario on the buick rendezvous site. More info coming in there.
  • als95gmcals95gmc Member Posts: 2
    I had someone replace my freeze plugs recently and since then the air conditioner won't turn on. When I switch the dial to Air the fan comes on, but the compressor is not kicking on. I had the same guy look at it. The compressor kicks on when he jumped it directly (if that makes sense) and he says the relay is OK. The fuse also checks out. Any suggestions? Is there another set of fuses somewhere? Thanks for any help.
  • repairdogrepairdog Member Posts: 948
    Possible faulty connector or loose pins in one, low pressure or pressure switch bad, compressor leaked so low pressure. Need to have test gauges to find so go to an AC shop and most do system test for free or low price before giving you an estimate.
  • als95gmcals95gmc Member Posts: 2
    Will do. Thanks.
  • 20blazer0020blazer00 Member Posts: 28
    I have a 2000 Blazer Ls.
    For some reason the a/c blows cold and then warm, it is constantly switching back and forth. I told the service manager about it today while it was getting a window switch replaced. I asked if if just needed recharged.
    He said " No, it wouldnt blow cold at all if it was low on freon. It must be a switch going out. "
    What do yall think? If it is a switch, can it be replced by yourself or have to have a shop do it? And what and where is this switch?
    Thanks
  • repairdogrepairdog Member Posts: 948
    If it has auto climate system (select a temp on the dial in degrees and it maintains it) you have an additional electric blend motor on the heater/AC box and they have a plastic gear that goes so cycles hot/cold as it can't figure out where it is. On top of the heater box and let the dealer do it. Motor about $200 plus labor.
    If a switch it could have an intermittent short or connection on the compressor or the pressure switch - AC guy can find it .
  • sbalsanosbalsano Member Posts: 5
    back in march the dealer repaired coolant leak from intake,replacing lower manifold and gasket. they also performed complete cooling system flush, 10 days later had to have it towed back because it started to blow hot from the a/c and temp gauge reading over heat.the dealer said i blew upper rad. hose,they replaced that. 6 weeks later same problem, this time i let it rest about 4 hours checked for leaks, it cooled and drove fine. i took it to another gm dealer, they could not find a thing wrong, they did pressure tests found no leaks, changed the thermostat just in case. now 10 days later same problem, i never had this before the first dealer visit. any ideas?
  • repairdogrepairdog Member Posts: 948
    Same answer as to your other dup post.
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