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GMC Safari/Chevy Astro Heating / Cooling



  • I'd still say its vaccum. I used to slam my hand on the dash and it'd work, then fail...But, do also check your electrical switches with a meter. They could be faulty.
  • westalwestal Posts: 4
    Recently replaced heater core because it blew out and leaked all over!! Had great heat before change of heater core, but now with new one no heat at idle. Took it into repair shop, they changed out the heater core again, changed out water pump, and still no damn heat at idle. But at high revs awesome heat. Tried to burp system to get air out. But there doesn't seem to be any air in there?!!? Any suggestions on what to do this is getting really frustrating in this -50 weather we have been having in Saskatchewan.
  • duecekdduecekd Posts: 19
    I am not a mechanic, but my 1st thought is the thermostat not working correctly. When you 1st start the van, watch your temp gauge. It should rise (mine gets to about 250F) then you'll see it drop noticeably. This is when the thermostat opens, which circulates the radiator fluid through engine and heater core. If you don't see it do this, it could be stuck open, in which the fluid doesn't stay hot unless it is running hard. For a quick fix, sometimes you can tap on the thermostat housing (don't beat it to death, you could break the metal) and it will break loose and work for awhile. But if this is the case, it needs to be replaced in any instance.
    That's my opinion, if anyone with more mechanic knowledge can correct or add to it, please help this brother out, HE'S FREEZING!!!
  • westalwestal Posts: 4
    Okay yes the thermostat was stuck open when i took it apart, so i replaced it. Now i can see on the temp gauge when it opens and closes again. I am pretty sure i have an air lock in the system, blows room temp at idle and nice and hot as soon as you get going a little bit. Been trying to burp the system but i just cant get the damn air lock out. Any suggestions its a 2002 GMC Safari.
  • duecekdduecekd Posts: 19
    When the van is idling, does the blower still blow out the lower vents, or does it just die. Or does it come out the lower vents and the defroster at the same time? I have read posts from other guys who had a problem with the blower not working at idle, but works when van is rolling. This is a vacuum problem. Check the vacuum line from the back of the manifold to the black vacuum ball located on the passenger side in the wheel well looking from the front. That vacuum ball I believe is supposed to keep up the vacuum pressure at idle. There could be a small hole in the hose, or a cracked stem on the ball or that other little black check valve looking thing on that line. Apparently these vans are notorious for brittle vacuum hoses that get cooked by the engine heat when the hose runs over the top. If you find a bad hose, I have replaced them with fuel line from the parts store. Just make sure the inside diameter is the same. Take a piece of the bad hose with you. Good Luck!
  • westalwestal Posts: 4
    Hey, no i replaced all those hoses the first time i started working on my van to make sure if wasnt the problem. It still blows hard on whatever setting i have it on, just cools down to room temp and as soon as i start driving it gets hot again. Thinking it is an air lock just cant get it out. Any more info would be great. Thanks
  • duecekdduecekd Posts: 19
    The only thing left that I can think of is to start the motor with the radiator cap off. The fluid will just sit there as you carefully look into radiator hole. Have someone Rev motor until thermostat opens. You should visibly see the fluid circulate in the radiator once the valve is open. If you see this, that to me would mean that it is circulating throughout the whole engine, including the heater core. I do know there is a damper door somewhere near the heater core inside the van on the passenger side. When you change the settings on the dash from defrost to heat, can you hear that door move? Mine makes a distinct noise when I change settings. I know I'm just grabbing at straws at this point, but I'm out of suggestions, and believe me, I know what it's like to be stuck on a problem, especially when your freezing!! Good luck!
  • fixer5fixer5 Posts: 5
    hi this is josef my chevy astro 97 blow out air but not hot enough rear fen blow only colt air position swich on dash boart works only high speed thenks josef
  • After checking everything else, I changed the bower motor and that fixed it. Wasn't that bad to install.
  • We`ve owned my wifes 97` astro van since 1998,
    after a few yrs of use , I started noticing a gurgling sound coming from the heater-core area but never looked into it since there were no puddles or leaks present, then we experienced the problems with no air/ac coming thru front-vents(but heated air came thru floor-vents at the time) but stayed like this for a coupe of years til` I found this site,
    I replaced all of the vacuuum hoses which did get the air/ac vent`s blowing cold air again... but now have no heat(I did feel heat at floor prior to replacing hoses), so I tested/replaced the thermostat w/new hoping this would correct problem(old one was ok) but still have no heat & did notice that temp gauge needle started fluctuating after new thermo(it goes well above the midway point to almost overheating(which it never did before)... then lowers itself...then goes back up again.. but it seems to eventually settle in between 1/4 & half on temp gauge which is somewhat higher than normal),
    when I turn the control knob to Mid-High Heat-setting I can hear a kind of clicking sound coming from the heat-core area & what I think is the air-mixture vent-door opening or not opening, the clicking/tapping sound is unfamiliar, I`m no mechanic but am somewhat mechanical, to anyone with similar problems....
    would the problem be in the Heater-core/air-mixture door areas somewhere?
    is the heater core or valve door easy to replace/get to?
    I have yet to check the core hoses for heat but this will be doing this if not today tomorrow, &/or will check for water circulation with radiator cap off to see if core may be plugged. Thank`s for any info or advice!
  • Update: yesterday I checked the 2 water hoses that run from the heater-core case to the 4-way metal valve under the air-conditioner evap cannister & find that the 2 hoses going to the core are cold & do not feel like there is water running thru them, the other hoses(water pump & intake manifold) to this valve are hot so I can only assume that this valve is plugged & not letting water flow to core?
    is there a way of checking this valve?
    will running engine like this overheat or damage motor?
    any help is greatly appreciated...thank`s!
  • just in case anyone is interested,
    I changed out the 4-way heater control valve which did get the heater & AC working again but, the temp gauge shows the motor to be over-heating, climbing well above 210 & gradually climbing,
    I checked the heater core for plugging prior to replacing heat-valve & water seemed to flow freely when added to low or high lines when using garden hose, new thermostat prior to this,
    one thing I did notice that the hose from the thermostat-to-radiator does not get as hot as quickly like it did prior to replacing heat-valve, the water pump(if I remember right) was replaced a few years back due to failure but no problems since w/overheating..
    could the water pump already be malfunctioning?
    I`m running into one problem after another with the cooling system since I started swapping out the vacuum lines to get ac & vents working...
    could use some advice or info if anybody has had similar issues.
  • can anyone tell me where is located resistor for chevy astro van 1997 thenks
  • tstormtstorm Posts: 10
    Yes the resistor on your Astro van is under the hood on the left side against the firewall. You will have to take out your wiper fluid / coolant resivour to get to it. There is a wiring harness that conects to it with five or six different colored wires. You unclip the harness and there are two bolts on either side of the resistor. If your having problems with blower motor speeds chances are the harness is melted. I think the blower motor does not work efficently and draws too much power causing the harness to melt. I replaced the blower motor, the resistor and the harness just to make sure the problem was resovled and I didn't burn up another harness or resistor. Of course you can get all three parts at the dealer but to save money I bought the resistor and blower motor at a local auto parts store. I could only find the resistor at Autozone, unless you go to a junk yard the harness will have to be bought at the dealer. The harness comes with a splicing kit. You will need to cut off the old harness and crimp the new harness on. You have to melt the plastic around the connections and electrical tape when done.
  • thenks you for advise { resistor} it is helpfull :)
  • des10des10 Posts: 1
    Hi, I have a 1998 Chevy Astro Van AWD, and the heat and ac is stuck on defrost. Also my rear heat stopped working shortly afterwards and just blows cold air. Please help me out.
  • tstormtstorm Posts: 10
    As far as your heat being stuck on defrost I'd guess that you have a problem with your vacume lines. They typically get old and crumble especially where they come close to the heat of the engine. Replace or repair the vacume lines and that should fix your control problem. Not sure about the rear heat thing but vacume lines could be the problem there too.
  • I have two 95 awd astros. They both give me the same problems. At 10 degrees f they take a half hour to get to operating temp. I replaced the thermostats with 195f and did not help. The older astros that I've had I never had these problems, but they did not have the oil coolers. Could I bypass the oil cooler for the winter to help them warm up quicker?
  • edcnyedcny Posts: 1
    The blower motor is under the hood on the pass side. You have to remove the wiper and radiator bottles and also the head light, then take out the 7 bolts that hold the blower motor in.
    Lastly you have to remove the squirrel cage (using an allen wrench) before the motor will come out.
  • sdrorisdrori Posts: 4
    My vacuum lines are dead. The ball is broken and I have no idea where to start? Is there a place where I can find a diagram of the vacuum lines and also where can I buy new lines to replace the old ones? What happens in my car (94 safari 4.3l) is that the heating and cooling goes to the defrost position when I accelerate and I have no cruise control. The ball is there but not connected to anything. Any help would be appreciated.
  • breezibreezi Posts: 1
    I have a 95 Astro I bought last year, high milage, in January heater blower would work sometimes but most of the time not. From what im getting from this sight that could be the vacuum lines.Would that not being fixed lead into other problems? Yesterday headin back to work on lunch van started to make noises then a burning smell. I got it back to the work lot and there it sits.I have never seen it over heat and although it was smouldering something it never lost any fluids. Seems to be coming from the pulley's. One person took a quick look and suggested that it is the A/C compressor?
    I'm really hoping for a less expensive answer if there is one. Found this sight last night and want to say thanks to all that help with the good advise!
  • tstormtstorm Posts: 10
    Sounds like you have two problems. The blower motor not working is not the vacuum lines. When the vacuum lines crack you can't control where the air goes but the motor still blows air... usually only out of the defroster. I'd say that your blower motor is dying and or the resistor/wiring harness is burnt.

    I have had a car in the past that had the A/C compressor freeze up so that is possible... I've not had your second problem with with my Safari... I did have to replace a blown serpentine belt at around 80,000 miles tho...
  • rab23465rab23465 Posts: 9
    The heater produces heat and also cool air when in the AC mode. Problem is the fan/blower only works in the first two positions. When I turn the control to the high setting there is no response. If I leave the control setting there the fan will come on every once in a while but not stay on steady. Everything works fine in the low and medium settings. The rear heater and AC fan works fine. Cany anyone suggest what may be a solution to my problem.
  • duecekdduecekd Posts: 19
    I have had a '92 and now a '95 GMC Safari and this happened to both. On mine it was the fan relay switch located on the firewall inside the engine compartment above the blower housing on the passenger side. Go to your favorite parts store and have them show you which of the 2 relays mounted side by side it is. And it's cheap and easy to replace. The one I got for the '95 was a little larger in size than the original, so it didn't want to mount in the exact same spot, but with a little American ingenuity, I worked it out. They may be able to test your relay, and if that's not it, my next suspect would be the blower resistors. Again, they are located in the same area, I think mounted to the blower housing. You can test them with an ohmmeter, or if they're really bad, it will be quite obvious, since they will be charcoal. Again, ask the guys at the parts store. That's what they get paid for. Hope this helps, and good luck.
  • 4damndogs4damndogs Posts: 1
    hi i have a 1998 astro awd with f&r air and heat. today i had the air on high setting, and the blower motor started making a humming sound. i know i have or had a mouse in the interior of the van but i dont think that would cause the blower motor to hum. is it on its way out or is there a way to tighten up the blower motor up. also the rear air does not blow, the rear heat blows (cold) so i know it is not the motor, i think it is the switch because i pulled the switch away from the dash and and if you juggle and twist it around enough it comes on. any ideas on eather one of the problems would be greatly appricated, i don't want to have to take it to the mechanic for things i can do my self. thank you in advance
  • beaubobeaubo Posts: 2
    02 Astro. Has about 75000 miles on it. After a car wash the fan stopped working unless you opened the hood and tapped on the blow motor housing or slammed the door really hard. What could this be? Is it the resitor? How do I get to anything in there? I'll keep searching but it's getting really hot outside and I don't want to put the new baby girl in the hot van at all! Help!!!!
  • tstormtstorm Posts: 10
    The resistor is behind the radiator overflow and the windshield wiper fluid resivour. It sounds like you may have a bad connection, maybe try cleaning the connection at the resistor and at the blower motor. The blower motor is hard to get to... it has a plastic cover over it which needs to be cut.
  • beaubobeaubo Posts: 2
    I'll give that a try myself as I believe a mechanic did this for me some time ago. Maybe they didn't. Best to do it yourself!
  • I hope this will help ,I am surprised with all the "techs' here no one has a heater vacuum diagram for a Safari to share out well heres my diagram for all to use
    gmc safari vacuum diagram
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