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Chevrolet Blazer Heating and Air Conditioning



  • duntovduntov Posts: 133
    Never go to a dealership to get service or repairs on a vehicle that is out of warranty. Dealerships have their hands full with warranty work on the new cars they sell and they discourage work on cars that are out of warranty. The dealership will give a car owner that has a car out of warranty a "courtesy bid" which will be far above and beyond the average independent auto repair shop labor cost. Today the dealerships make more money off warranty work than from new car sales.

    1998-2002 Chevrolet Blazer (full size) A/C - Heater Solenoid Valve
    AC Delco #15-72182
    GM- #16171742
    MSRP: $120.57
    Dealer Cost: $62.70
  • jlflemmonsjlflemmons Posts: 2,242
    Something else to watch for is the disintigration of the rubber vacuum lines running from the intake manifold to the vacuum canister and that area. They will croak after about 6-8 years and when they do, the AC blows out the floor.
  • cach22cach22 Posts: 12
    '98 Blazer LS
    4 door
    130,000+ miles
    I do NOT have automatic temperature control.
    The A/C blows only hot air. The vents DO get warmer if I turn the temp dial to heat. I do not hear the compressor clutch engaging nor do I see/hear the accompanying load increase on the engine. I have checked the low side pressure and it actually reads high (in the red on the cheapo gauge that comes with the cheapo recharge kit).

    How do you check the compressor to see if it is bad or not?
    Or, is there something else that may be causing this?

    I replaced most of the A/C system a couple of years ago with the help of a mechanic friend. The compressor shelled and contaminated the system with bits of metal. We flushed, replaced parts and had the whole thing working great. About 3 months later I parked it... for about nine months. It was when I started driving it again that the A/C no longer worked.
  • dfhltddfhltd Posts: 11
    First check the compressor is not frozen by seeing if you can turn the shaftthat engages the clutch. If you can't get leverage to do that then heres another idea. There is a wire that goes to the clutch. Disconnect that and supply 12 volts directly to the compressor clutch to see if it engages and the compressor will turn. Don't let it run very long! Just long enough to prove the compressor is turning.

    Assuming that it will turn then the problem lies elsewhere. The wire you disconnected is the signal to engage the clutch and the electricity isn't getting through. This is because there are a couple of safety sensors checking for pressures in range. The fact that the low side is out of range indicates the low side sensor is not allowing the signal through. The high side may have a sensor too. In any event these are safety devices to prevent the compressor frombuilding up too much pressure and exploding the pipes and connectors. This is what happens when air gets in the system. The compresor will keep compressing the air until something bursts. Normally the coolant will be compressed from a gas to a liquid and pressure will remain normal. But you probably have lots of air in the system. Coolant leaks out generally through the seals where the hoses connect to the compressor and dryer etc. They have little O rings and special seals which may have cracks or are installed incorrectly. I got some seals from the auto part store that looked right but wern't. this part is really tricky and could be your problem. Anyway you have to get all the air out of the system before you recharge. You can't just add more coolant. That won't work. Then when you get it running again there is a test that can detect leaks which you should do around any thing that has seals in it. Good Luck

  • cach22cach22 Posts: 12

    How easily should the shaft turn? I tried to turn it and it did not budge. I actually scraped some metal filings off trying to get it to spin. Do I remove the belt to try this? Or is it safe to say that it is frozen up? I priced a new compressor and I must say I am not looking forward to replacing this thing.

    I have yet to try applying any voltage directly to it. I have to rig something up. Plus I need to wait until it stops raining.


  • dfhltddfhltd Posts: 11
    It's frozen. It should turn pretty easy. The clutch drive plate is on the front and easy to get to. It's disengaged from the drive pully. Normally the electricity pulls the drive plate and pulley toghether. You don't need to remove anything.

    As far as the compressor it ony two bolts on top holding it on. You can get them off in 2 minutes. Disconnect the hoses and take off the drive belt. You can drive it that way until the new parts arrive. The AC belt doesn't drive anything else I don't think. You can try again to turn the compressor but it sounds like its frozen.

    When you charge the system you need to put quite a bit of ester oil in the new compressor. You can buy at the local auto store.Without it it's like running an engine w/o oil. It will seize.

    You need to flush the drier and evaporator and condesser to get any metal filings out that may have come from the compressor when it siezed. Figure out which way the coolant flows in the system and then blow through the dryer, condenser and evap in the opposite direction. Use AC flush and clean that you can buy at the auto store too. I think I used a hose and funnel to get as much flush as I could and then an air compressor to blast it through. I don't know if this is the approved way but it worked.

    I bought a new compressor with a new clutch online for $160 - $200. I assembeled evertything and took it into a automeotive AC shop and had the system evacuated and filled with coolant for about $85. They can check to see if the pressure is right and the seals arn't leaking as part of the service.

  • rjmacrjmac Posts: 1
    I can't take the sloshing noise under the dash any more. Before it really gets hot and musty smelling I would like to blow the line out with air (did this on a minivan years ago, worked great). PROBLEM I can't locate this line. I now have the wheel liner out and still can't see it! Any one got advice. Last fall the local garage had it on their lift and they couldn't find it either.
  • dfhltddfhltd Posts: 11
    I don't know if there even is a dripline but the sloshing doesn't have to do with that. If there is a drip line it has to be located under the evaporator which is bolted to the engine side of the firewall in the middle. I'm guessing there is a hole or something that lets condensation just drip out the bottom on the ground. The cover comes off so you could loook insdie and see if there is a hole in the bottom under the evaporator core. There may not even be a hole.

    The sloshing noise probably is the heater. I noticed that the heater core is pretty high and the hoses leading to it are longer than they need to be so they arch up. If there is air inn the system it will goe to the highest spot which is the heater core and hoses. Re route the hosesso they are lower than the heater. Make them shorter if necessary. Then find a way to bleed the air out of the system. Once there is no air in the system the noise will go away.
  • phillip64phillip64 Posts: 1
    Issue: I have no heat regardless of temperature control setting with the exception of when I set to full clockwise, and then gets hot as heck. AC works all too well and will freeze you out of vehicle. Again no adjustment with temperature control just cold as heck unless I turn temperature control fully clockwise, then heat takes over and it gets too hot in vehicle. Just a slight adjustment counterclockwise and all bets are off, no heat. Vehicle is equipped with auto climate control, just does not seem to work. Any and all advice welcomed. Thanks
  • My air and heater both work but in differant settings. Air only works on far right of dial and heater on only works on center settings. Air/heat only blows out dash at you and alittle at windshield no matter what the setting on the dial. All fan settings work fine. Is it just a bad dial? Any ideas on this? Thanks
  • jlflemmonsjlflemmons Posts: 2,242
    Check the vacuum lines running from the intake manifold over to a tee near the brake vacuum booster and on to the vacuum resevoir in the left front fender. Very common for these to rot and leak with age, and will cause the symptoms you have described.

    Good luck
  • Guys my WIFE'S 2002 blazer has no heat .. i pulled the return heater hose and NOTHING.. one side is hot and the other nothing( its a little wet but no running water)... ???? can I use a air line to maybe blow the core out??? or is it to late and i have to replace it......????
  • jlflemmonsjlflemmons Posts: 2,242
    Backwash it using a garden hose, just don't crank the pressure up too high. Get garden hose repair fittings and install them on heater hoses a couple of feet long. One will be larger than the other. Hook the supply side hose to the "exit" tube on the core, and the drain side to the other. I *think* the smaller one is the supply side, but not sure.

    Gently turn on the water and watch for crud to come through the drain side. Once it starts flowing freely, let it run until the water coming through is clear.

    Put everything back together and get the system flushed and refilled with fresh Dexcool. Do not try to switch to standard antifreez unless the whole cooling system is flushed until the drain water is drinkable! (just kidding, but it needs to be completely flushed) Those two types of antifreeze will not play together, and even a little bit will cause problems.

    With a little luck, the corrosion will not have eaten through the heater core.
  • Issue: no heat. A/C works fine, blower works fine, but it seems when I turn the temp control knob, it turns too easily. I understand there is a baffle that the knob controls to reroute from A/C to heat, but not sure where it is or how to get to it. My thermostat is fine, but going to replace it anyway, along with a new radiator cap. Have not completed a coolant flush, am scheduling that in the next couple of weeks. I also heard it might be some sort of relay switch, located under the hood near the firewall? Any assistance?
  • dfhltddfhltd Posts: 11
    The first thing you should do is go to the dealer and get them to copy the diagrams from the parts catelog. There are acouple of them that show different views. Also get the pages which list the parts and description that go with the diagrams.
    this will help you find the baffels or doors (3) that control airflow and the parts that control them. Check the hoses at the firewall going in and out of the heater to see if they are hot.
  • Hello I have a 1997 Blazer. The heat didnt work when I got it. I direct wired the blower to the batt and the motor was fine. I replaced the switch that operates the fan speed and it worked for a week. Now it only works sometimes. If I hook a direct connection to the fan fan it always goes on. Also I noticed that the heater doors dont appear to be working I can only get defrost and some heat out of the bottom. are these electric or vaccum? I live in upstate NY ( 14 degrees here today )so I really need the heat and defrost any suggestions?

    Thank You
  • Hello I have a 1997 blazer. I took it to get it inspected but because I installed a new battery and only drove 40 Miles it mech. said it wouldnt read it yet. I have since put on 140 miles and 2 days ago the check engine went on and stayed on for the afternoon. The next day it was off and hasent been on since. I brought it back for th einspection and again it read " computer not ready to read) Can anyone tell me why or what I can do. I need an inspection. Please note I took it to a friend of mine who has one of these hand held computer checks and he said it didint show any errors that I should be fine. This was BEFORE my return to the shop for inspection.
  • I have plenty of heat. The problem is it only blows out of the vents no matter what position the switch is in. I replaced the control panel but the problem remains.
  • jlflemmonsjlflemmons Posts: 2,242
    Check the vacuum lines from the intake manifold, to the tee near the brake booster, to the vacuum resevoir in the drivers fender behind the underhood fuse box. These lines rot and since the controls are vacuum operated, they won't work.

  • My girlfriend owns a 1998 Chevrolet Blazer....She was told recently by a mechanic that if you don't use your A/C much, it could actually harm your engine. Is this true at all ?

    I would appreciate some help on this. Thanks so much.
  • tidestertidester Posts: 10,059
    I've never heard that before and don't know how it's possible but maybe someone else can offer some insight.

    tidester, host
    SUVs and Smart Shopper
  • dfhltddfhltd Posts: 11
    Whoever told your girlfriend that is nuts. AC takes power from the engine just like the alternator, the power steering and the transmission and wheels. The AC is no different. That's what the engine is there for. Engines in cars made without AC do just fine. There is no way that not taking energy from the engine is going to hurt it.
  • steverstever Posts: 52,572
    In the old days, you were supposed to run the AC a few minutes a month all year round. As I recall, this was to keep the seals flexible (in the compressor I guess).

    Nowadays the AC will kick on when you run the defroster to dehumidify the air, so you shouldn't find anything in your manual about running the AC. And I don't see why never running the AC would hurt anything.
  • jlflemmonsjlflemmons Posts: 2,242
    Has nothing to do with harming the engine. But you should run the ac or defroster at least once a month for a minute or so to keep the seals lubricated and the oil moving across the moving parts of the compressor.
  • dulinaadulinaa Posts: 10
    Try looking straight down the firewall from where the a/c lines enter it. Do you have any condensation on the ground at all? Is the front floor carpet wet? There isn't much room for any kind of sloshing around. I have had heater cores with trapped air make that sound, especially the chevy trucks. And on my in-laws Jeep Cherokee, that drain was plugged bad, but it was inside the square tube subframe that extends from the firewall, couldn't get to it to blow shop air up to clear it.
  • dulinaadulinaa Posts: 10
    It will not harm your engine, BUT it can ruin you a/c by not running often. Its got the Use it or lose it policy. Your a/c system has lubrication oil mixed with and circulated by the refrigerant. The seals can dry up and crack, especially the front shaft seal on the a/c compressor, causing all the refrigerant to leak out.
  • steverstever Posts: 52,572
    I just downloaded a '98 Blazer owner's manual and I don't see anything in there from GM advising owners to run their AC at any time. It may have been an issue in the old days but I don't think it must be a problem now; otherwise the manual would say something.

    How To Find Your Car Owner's Manual Online
  • jlflemmonsjlflemmons Posts: 2,242
    Running the compressor is an issue in any automotive system. It may not be mentioned as most folks will use there defroster/defogger during the winter, and thus run the compressor.

    It may not be as big an issue with R134A, but was definitely an R12 issue. Most systems now days use very, very little refrigerant. As an example, the S10 series Blazer/pickup uses less than 28oz of R134A!
  • steverstever Posts: 52,572
    edited June 2010
    I think the long term trend in cars is to lessen required maintenance as much as possible. So my feeling is that the engineers have improved the seals so that there is little risk of failure by not using the AC. Plus as you say, the AC comes on with the defrost.

    Then again, I suppose the manufacturers know that most people trade cars every 3 to 5 years and so they don't mention maintenance for marketing reasons, since many (most?) of us don't want to maintain things. But both my cars are over 10 years old and I just use the AC or defrost as needed, not on some "monthly" schedule.
  • I own an 04 Blazer LT with 4WD and the heat was blowing cold. The mechanic received a code indicating the thermostat needed to be replaced. They also replaced and winterized the antifreeze, etc. That was on Thursday. On Sunday it was again blowing cold.

    I felt it was a partially clogged heater core but they replaced the thermostat which seemed to resolve the issue for about 2-3 days.

    Any suggestions and should the dealer do the repair free of charge for not fixing it initially?
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