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Pontiac Montana Heating / Cooling Problems



  • richardp2richardp2 Posts: 4
    I am having somewhat the same problem with my 1998 Montana. It just started a few days ago not blowing any air of any temp out of the A/C vents. I read another blog here and am thinking a vacuum hose maybe loose or broken that controls the linkage of the blower. I can hear the blower fan blowing it just doesn't come out of the vents properly. If the vacuum trick works I will write back.
  • fixcarfixcar Posts: 1
    I have a 2000 Montana that I purchased from a neighbor two years ago. It runs great now, but I am not looking forward to winter, as the so called "heater", puts out such a little amount. Everything in the climate system has been checked/replaced (including the thermostat)and still no heat! I am thinking that there might be an aftermarket electric type auxiliary heater available? These were available years ago, but I think there were fire related problems, so they took them off the market? Are there any new realistic ideas of how to get more heat? What was GM thinking; making a car with no heater?
  • Help! My 2002 Montana will not put out any warm/hot air. With the temp control at full cold the air moves just fine. The engine runs just fine and at normal temperature. When I turn the temp to hot the air flow goes to nothing and I hear the fan running just fine. Is there a door directing air over the heater coil? Where is it and how do I get to it to see if it is working? Thank you for your help!!!
  • mailmail Posts: 10
    Hi Mrall, your posting was Really helpful for me. I was wondering if you had to drain coolant from the engine in some way in order the change the thermostat? I can't seem to find any information on that and I was really impressed that you were able to replace it with only having to take off the air filter and tubing to the throttle body ! Thanks again !!! K
  • We replaced the thermostat in our 2001 Montana. Now it seems even worse! The temp goes up very fast when your driving and you have to turn the car off and release pressure/steam from the bleeder vavle by the thermostat. Is it possible to put the thermostat in wrong? Any suggestions you might have would be greatly appreciated! :confuse:
  • 24randyo24randyo Posts: 6
    I have a 1998 Trans Sport Montana. Was having the same problem, it kept losing all of it's refridgerant, over about a two week period, and blowing warm air. Had it recharged with dye, still couldn't see a leak, but it still leaked out in two weeks. When recharged with dye a second time, the mechanic finally found that one of the pipes in the cooling manifold in front of the engine had been rubbing against a part of the transmission and rubbed a hole. The hole was against the transmission and the dye was undetectable as it leaked out because it was such a slow leak. He changed the manifold ($80.00 part, 1 hour labour) and it has worked ever since.
  • I'm having the same problem. i have replaced the thermostat and still no heat. I have the same year of van and would like to get this problem fixed as it is quite cold here in canada. Can anyone suggest any ideals or fixes to this problem.
  • Mine is a 98 Trans Sport Montana. I live in Canada as well, and have had very little heat when it gets below freezing. I was driving on the highway in December, with very little heat, and my temp guage went way up. I pulled over, shut it off, checked the coolant in the reservoir, seemed OK. I thought it might just be the thermostat. Started it up, temp was back down, drove down the highway a couple miles, and it was right back up again. This time, it didn't want to run very well. Had it towed to a garage, found that one cylinder was full of anti-freeze. Once he tore it apart, found that one cylinder head was cracked. It had never been using anti-freeze in the past, and had never been overheated that I know of, so somehow this head must have cracked as I was driving. It was $1500.00 Canadian to do the repairs (which I have found out since was a pretty goood deal). I thought that this may have solved the lack of warm air problem, but it didn't... it hasn't changed at all. Apparently, the no heat and the cracked heads or blown head gaskets are very common for this type of GM engine (3.4 litre V6). All I can say is, you are either lucky or you're not when it comes to this kind of thing with any vehicle. Always pay attention to your coolant level, and don't just look in the reservoir, take the rad cap off and check there too!
  • kenniekennie Posts: 38
    I have been dealing with the same heat problems. VENT AIR FLOW: If you are having trouble with AIR FLOW from the vents, I had the same problem and it was fixed after the dealership traced one of the vacuum hoses (about 2-3 mm black wire) that runs over the top left hand (pass side) of the engine and found two cracks, one on top of the engine and the other down behind the battery/fuse box. Back to the heat problem now... van heats up to operating temperature but occasionally goes 1-3 ticks higher but does not overheat but when sitting at idle (say at a light) the heat coming from the vents quickly turns from semi-warm to cool. I've had the coolant system flushed (not the heater core thou - they charge separately for that) but no change in heat. I'm tempted to have the core flushed but will hold off until I look at other things first. When I step on the accelerator I get better heat - revving the engine gets good heat (temporarily) until the engine returns to idle. I'm suspect of two things (again i'm no expert), a restriction of some sort is keeping fluid from either getting to the heater core (air lock somewhere) or a heater core blockage/partial blockage. Since I don't know how the heater core is designed i'm not sure what the likely hood of an airlock/blockage. The other thing i'm considering looking at is the auxilary coolant pump installed on 2000+ vans and manually installed on earlier vans in canada (because its cold here). The aux pump is located around the coolant tank (RHS) and is attached to a temperature switch in front of the engine rad. I'm not sure what i'm going to do next but probably fool around with it before taking it to the dealership... $125/hour adds up really fast and want to use a little grey matter and try a few things first. Your comments/suggestions are always welcomed. I think i'm going to try to lift up the front of the vehicle and try to burp the system as discussed on other feeds then possibly pinch off the aux pump, remove and test with a bucket of water to see what it is actually pumping and when (at what temperatures) it is pumping. Went to the dealership and asked about this pump and they said they have never heard of it going.... but then again FORD dealerships won't admit their springs break (when 1000's of people it has happened to) and the GM won't admit to glasket failures in their montana's... oh so many examples. Anyway keep the ideas flowing everyone. Maybe there is someone out there who has removed and tested a aux pump.. what am I going to see/expect? Cheers.
  • kenniekennie Posts: 38
    2000 Pontiac Montana heating problems in the winter time...


    I was delighted this weekend to find an unexpected solution over the weekend that may help some readers that have higher mileage Montana vans. My previous post outlines the problems I have been faced around heat in the van when it gets cold outside (being from Alberta). Through the process of elimination I thought and read about the various components of the heating systems that enables heat in the cabin. Fixing the vent was the first step as the air flow was definitely not producing what was needed. The next was the coolant replacement that needed to be done anyway so doing the flush was practical to do. All the hoses appeared hot just from inspection the thermostat was doing it's job in keeping the engine a fairly constant operating temperature regardless of the weather. So it came down to some sort of blockage or air pocket. I eliminated the air lock with the "professional" coolant flush. 2000+ Pontiac Montana vans have a factory installed Auxiliary Coolant Pump (previous years had them installed by the dealer). These pumps enable greater flow of hot coolant to the heater core needed for cold Canadian winters. I was told that these never fail by two separate dealers. In addition, i've looked high and low for information on these pumps but there does not seem to be any.

    So here is what I found... first the pump should only work on temperatures lower than 'around' 0 degrees controlled by a temperature switch near the front of the radiator behind the bumper. Even though it appears to be running and the hoses are hot, this does not guarantee that it is working. After removing and disassembling it, it turns out that the motor actually spins a magnet that in turn spins an internal propeller to move fluid. If the propeller damaged or seized the motor will still spin giving the impression that it is working. Also, if the motor is not running (temperatures above 0 degrees), then a small amount of fluid can still get through thus the hoses remain hot. With the pump not working the symptoms of little or no heat unless the engine is revving makes perfect sense to taking a closer look at the aux pump.

    Anyway, when I removed it (if you have the skill) and carefully took it apart (only if you have the skill) it is possible (not guaranteed) you may find that it is seized. Using some common sense, I remove it from the engine (without draining coolant - use a bucket to hold up and drain the hoses out a bit), tested it and then proceeded to disassemble/clean/re-assemble/re-test it and put back on the vehicle (put the pump on the outlet side then fill the pump and other hose with fluid/water unit at the top then immediately put on the other side quickly so that minimum air gets in). I've got heat now just like I did before.

    I'm trying to teach my son that using your head and moving through things carefully and thoughtfully you can troubleshoot many thing that even a dealership would not catch right away because we have the free time and they don't. If this information helps solve your problem and you don't need to take your vehicle to the expensive dealership then please help me with supporting the Multiple Sclerosis Society of Canada in which I support whole heartedly each year at the link which you can paste in your internet browser - it is the MS Society of Canada Site for which I have a annual team that raises money for those with this terrible illness and I will show him how being mechanically inclined in life helps others:

    All for now... and good luck !
  • jdoddjdodd Posts: 1
    I have a 1999 Montana. The rear fan shut off the other day and wouldn't come on untill I hit the back driver side panel. I am think a bad connection but want to know what all you guys did to fix this.
  • I am looking to buy a 2001 Montana from a private owner. How can I test to make sure that the AC is working. He said that AC will only work when the outside temperature is above 10 degree C. Is this true?
  • kenniekennie Posts: 38
    That seems really strange to me... the air works in the winter time b/c it greatly decreases the time it takes to de/fog the windows when it is turned on. Also, did you know that on some vehicles the air comes on (regardless if the ac button is in) when you put the vehicle vents on defrost? I'm pretty sure that happens to my montana b/c I started it up once (with AC off) and on defrost and felt the ac pipes and they were ice cold. When buying a montana watch out for transmission problems (hard shifting - take it for a long run to make damn certain it is not hard shifting)... also ask if the van is loosing coolant... if it is you could have a upper or lower head gasket leak which may have been seeping coolant into the engine and the bearings will fail needing new engine.... this is VERY COMMON on the montana... I would call the service center to see what work has been done to ensure that coolant levels are stable. Read many feeds on this !!!! ... choose a montana VERY carefullly !!!! Heat in winter is not great in these vehicles too. Good luck.
  • kenniekennie Posts: 38
    Well, it has been about 6 months since my last post regarding my 2000 pontiac montana with heat issues. Today I fixed it - it ended up being a blocked heater core (front one, the one in the rear was ok). Over the past 2 years heat in the front of the van has been minimal, although I was able to improve it by cleaning the auxilary pump (see previous posts) and by attempting to get air out of the heater cores (previous posts) - these two things improved the heat in both the front and rear cores but the front core simply produced less and less heat until the last month it was blowing cold all the time except for maybe once a week it would blow a little warm and then right back to cold again.
    My diagonostic started with the fact of my previous posts - air locks, aux pump restricting flow (yes - this was happening and fixed it). The rear heater was working very well and producing full heat. I inspected and diagrammed the coolant flow of the van as follows: out of the back right of the engine, into the auxilary pump, out of the aux pump (out of the side of it) to a T-split (one going to bottom of front heater core the other goes to the left and down the firewall under the van to the rear heater core. The return pipes from both heater cores come together into a 3-input T (just above the previous input-T) which leads into the cross pipe which feeds to heat the throttle body and then crosses right in front of the engine (metal black pipe) into the coolant pump (big one run by the motor belt on the left of the engine).
    From this diagram I could conclude that the rear and front heater cores are directly connected to one another in a complely separate system - out of the engine and back to the coolant pump. Therefore, the only reason that there is heat in the back and no-heat in the front core is that either the heater core doors are not opening property or the heater core or T section is plugged.
    I opened as much as I could under the dash to see if the doors are opening properly using the heater switch on the dash...once things are removed and you turn the switch from warm to cold you can see an indicator on the left side of the heater box that slowly turns with the turn of the switch. THere are markings on it to show its maximum and miniumum and mine appeared to match up so I know it was turning - plus I could hear and feel changes happening when I turned the switch - air flow change and temp change (slight). Therefore I ruled out vent's not opening propertly - not absolutely but a pretty good idea they were working. The temp vent is not controlled by vacuume like the other switches are so I was not concerned with that... vacuume controls recirculate and fresh air for example.
    One think I noticed is that when there was heat, if I left the air flow on 1 out of 5 the air was warm.. the more I turned up the blower the colder the air got.. therefore I concluded that the front heater core was not keeping up to the air flow therefore leads me to believe coolant flow to it was hamperred to some extent.
    Front the schematics I determined above, I decided I wanted to flush the heater core rather than remove it because it was going to cost $800+ to do, not including the dealership wanting to diagnostics. The typical way is to remove the hoses from the heater core which is almost impossible - just take a look to see if you can see them ... I looked from below and above and even taking things off it was almost be implossible although rotating the engine forward (not that hard) it would make it easier but still - a frikin crappy job.
    So this is what I did... emptied the rad (from the bottom plug - be careful not to break it) into clean containers since I wanted to re-use any clean fluid. Next, I disconnected the output end of the auxilary pump (making sure not to spill any fluid) and put the pump end pointing into the coolant reservoir. Next disconnected the small hose from the coolant pump (big one) going to the head of the engine (disconnect top of hose not bottom) and then removed the pipe screw on the left side and lifted the pipe out (carefully) and put a piece of hard plastic with a bag on top jimmied between the pipe bottom and the pump hole. What you have now is a loop of input and output to the 2 heater cores. The aux pump end sitting in the resivoir leads directly into the engine and is placed here so that any pressure/air in the engine pushes fluid into the resevoir and not the ground !!!
    Next I wanted to get out any fluid in the heater cores and lines so I hooked up a low presure air compressor to blow air into the outlet (left side hose connected to cross pipe (on left) which pushed fluid out the aux pump hose (hose hanging that was disconnected off the side of the aux pump) - hook up a clear hose to this using precausion that you DO NOT GET ANYTHING INTO THE SYSTEM - no plasic, dirt, rubber, tools, ends, etc.) and run into an empty ccontainer for recycyling. When I ran air though emptied into the container and all kinds of crap came out ... pushing air in this direction is opposite to flow so anything stuck would be pushed out.
    After I got all the fluid out I could, then I hooked up a hose (instead of air) to one side and attached another milk jug to the other end (right side). I put the water on low and ran until the water coming out was clear - it took 2 milk jugs and the second jug I used higher water presure - but not full.
    Now the cores are clear of coolant so I hooked up HOT WATER from the house and turned the presure up slowly until it was fully flowing and left it run for about 10 minutes and letting it drain down the driveway. I am no expert but if you are having any resistance at all DO NOT PUT MORE PRESURE than that is coming out the other end !!!!
    I then disconnected the water and went back to air to push out the water I put into the cores. Once clean I hooked everything up and cleaned out the coolant resevoir (recycled all the crap I got out of it into a container I could take into recycling) and hocked everything up, made sure the drain plug was back in, filled the system, removed air from the system let heat up and to ensure the entire system was filled properly with no air pockets.
    WAMO.... i've got FULL heat in the van again after 2 years or more of slowly decreasing heat due to blockage. Since the back core was producting heat before it was correct for me to assume the from was blocked.
    I would like to comment that I had the van into the dealership twice and both times they blamed my in cabin air filters, vacuume line problems (which they claimed they fixed) and an engine overheat problem that they claim I need to look at... this is not the case.. the engine does not overheat and does not loose coolant and a pressure test was done twice and there are no problems here.
    Anyway, I wanted to pass on what I have done... this summer i've also replaced spark plugs (not for the faint of heart) and completely cleaned out the throttle body.
    It's been a go
  • kenniekennie Posts: 38
    Continued from my previous post.....

    It's been a good year... finally I won't freeze this winter.
    Please please please please be environmental conscience when you are doing such work... I did not drop a single drop of coolant that I could capture to take into the recycling center - it takes very little more effort to be responsible in this manor... please take the time to work carefully and understand what you are doing, the potential concequences and if you do not understand EXACTLY what is happening using these instructions without making assumptions then PLEASE DO NOT USE ANY PART OF THE ABOVE. I AM NOT A PROFESSIONAL BUT I DO HAVE GOOD DIAGNOSTICS AND TROUBLESHOOTING SKILLS THAT HELPS ME UNDERSTAND WHAT I AM DOING. I AM NOT RESPONSIBLE FOR THE ABOVE INFORMATION - USE AT YOUR OWN RISK.
    Take care... Kennie
  • Hello Kennie,

    I've a Montana 2000 and got the same problem that yours. I did what you've said and it worked for my van too. So, I canceled my appointment with the dealership and save a lots of money. As suggested from you, I made a donation ($25) to the Canadian Society for Multiple Sclerosis (CSMS).

    So, we are probably three satisfied persons now: you for the usefulness of sharing infos and influencing someone to give a donation; the CSMS for a $25 donation; and me for having probably saved a couple of hundred dollars.


  • kenniekennie Posts: 38
    Hi Carfixer4u,

    Just wanted to send a sincere thank you for your donation. You are the first person to donate and it will be a good story to share with my family tonight and especially my son. I certainly feel greteful that I was able to help in some way - even though i'm not an expert in this area. Much much appreciated but not at all expected. Take care and good luck with your van.

    An unfortunate story with my van as of late... the head gasket blew and cost me $2000 to fix at a engine rebuild shop (was going to be $2600+ at the dealership). When they took things appart the gasket was so bad that it corroded the heads and 3/1000th needed to be taken off the heads to make them true to put back on. The dexcool becomes acidic and eats away at the poor quality of gasket GM used at that time - that is why you hear so many vans having this problem but mostly the manifold gaskets, not so much the head gasket. Lucky I was not on vacation somewhere. Best to keep an eye on the oil color and the coolant color to ensure you catch it early if it should happen to you. The proceedure for cleaning the heater core I described had nothing to do with the head gasket failing... it was just time for it and I think the problem was coming for a long time from what they told me.. he could tell the multiple locations of leak on both front/rear head banks.

  • we own a 09 montana sv6 we bought in sept of 08 in nov of 08 we come to find out that our van has no heat at a idle it can run for hours and never clear frost off the windshield now living in sask this does create a problem for one why have comand start if the vehicle dont warm up that is a $300 dollar option thats a waste of money now they have done all kinda of things to this van proping the van on one end in the air for several hours (thinking theres a airlock) to now putting foam pipe insulation on the heating line which last weekend driving in the slush on the hiway it all got ripped off (imagine that ) now after a year and a couple of months of fighting with gm the problem is still not fixed and i was told thats just the way the van is now ive tried several times to trade this reject van off but apparently montana vans are not worth nothing anymore and gm does not seem to care they have my money and with threats of stopping payment there responce was it wont bother us it will just ruen your credit rating and if you turn the van in then its called a volintary repo so its your loss so here we go through another winter going to hockey games hauling our kids around a praire winter with no heat in our van if in sept of 08 id have known this brand new van had no heat i would have not bought it will i buy another gm product that im not sure of by the way i have been treated after all i have been very paicent (till now ) if i do buy another one it wont be in the summer thats for sure it will be in the heart of the winter for sure but for now i guess to warm it up at -40 i will fire it up and throw a brick on the peddle to clear the window off i guess my options have run out
    p.s if anone has plans of how to mount a wood burning stove in one of these van please drop me a line
  • mailmail Posts: 10
    Just wanted to provide a few comments which may or may not help. Reading my post regarding heat (the one that describes the process to flush your own heater core) would provide a fair amount of information regarding heat in these vehicles. The van being so new I am immediately going to suspect one item (if your van has rear heater core) is that the auxilary pump is impeeding the floor of coolant to your heater cores in some way, or one of your t-values between the output of the engine coolant and into the aux pump and back to the black crossover pipe (that crosses across the front of our motor along the spark plugs) is somehow blocked. I can't see how your heater core is plugged but flushing it and actually watching what volume of coolant you can get through it would certainly help eliminate anything to do with the path of circulation. If you are not getting coolant out of your motor it would immediately overheat. So if you are not getting ANY heat in the van (front or back) then other things could be that your heater core doors are stuck closes bypassing your heater core completely... since this door is MOTOR driven (not vacuum driven like the other heater controls) it is possible that the motor is burned out to the closed position OR the flaps (valves or doors) are stuck. Are you getting any air flow throu the vents? When you turn the heater from cold to hot do you actually hear a change in air flow inside the dash?... look at my other posts for more info... if I can help in some way I will. I am sorry that if you have tried and investigated all this already... don't know how far you have gone with the dealership but my experience is that you can not trust their diagnosis... I had my van in 3 times they always seem to have another reason why I was not getting heat. Finnally I had to test, troubleshoot and fix myself as you may have read in earlier posts.... which is quite frustrating. Your van may not be an extended van with rear heater core like mine so the short version maybe a little different... and mine was 2000, yours is 2008 so again, maybe it is different but the way GM saves money it is likely exactly the same systems.
  • After a short trip today, i noticed a rattle sound coming from the engine compartment. Upon arriving home, I opened the hood and found the rattle appeared to come from the compressor. If I turn on the air, the noise stops. Any ideas ? Could it be a clutch on the compressor with bad bearings ?
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