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Pontiac Montana Heating / Cooling Problems



  • 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 ?
  • spike99spike99 Posts: 239

    As a suggestion, take your GM vehicle to your trusted auto shop and ask them to confirm your vehicle's "sound making" part. Sometimes, sound travels across attached items - which makes it hard to confirm the "core root" of the problem.

    Assuming the noise is from a "worn out" AC clutch, I'd get it fixed ASAP. We had a 2001 Sunfire that blew its AC clutch. While getting repaired, the auto tech showed me 3 other broken (worn out) GM AC clutches in their garbage can. Thus, proving that GM AC clutches are under built. Getting the vehicle's AC clutch fixed ensures "better" main belt alignment. Thus, lowering its risk of blowing a main belt. Especially if you travel in locations that lack road-side auto shops. Also... If replacing AC clutch, do get its main belt inspected / replaced (if needed) as well. Many auto techs like to replace both at the same time. Especially on older GM vehicles. Thus, do proactively "budget" for both critial item replacements.

    Hope this helps...

  • thanks for your feedback.
    i read somewhere to spray some wd 40 on the clutch.
    i did so and the sound / rattle was gone.

    problem appears to be solved, should i still be concerned ?
    it's winter now, won't need the ac for 6 months.
  • Last week, the heater stopped blowing in my 1998 Pontiac Transport van when I start it using the (ProStart) remote control starter. The van starts fine with the remote, but the headlights and heater don't work until I actually go in the van and turn the key to on. The heater is left turned on the mddle blower setting all the time, so it isn't a problem that it got turned off previously. Any ideas what would cause this? Thanks for any help!
  • What did you use to access the lower thermostat housing bolt ?
    It is down behind the exhaust manifold pipe on my V6 3.4l.
  • kenniekennie Posts: 38
    If you are not taking off the black crosspipe (that connects just over the thermostat into the throttle body) then it's a [non-permissible content removed]. I can't remember now but I think I took off the throttle body (because I was going to clean it anyway and replace the gasket - for fun) so it made it easier for me. Some places on the internet say that you can
    get a wrench in there... but I can't see how, it would be quite hard to do and I tried and couldn't. Even with the throttle body off and the cross pipe pulled out of the way its not a fun housing to get back on... Hope this helps !
  • mbettsmbetts Posts: 1
    I know it is cold outside (0 F),but after driving 30 min. it isn't getting very warm inside cabin .I ran van with heat on & it got a little warm & then the windows began to frost, so I turned it to defrost & it worked & then we were cold, so I had to keep going back & forth---we recently traveled 1000 miles to higher elevation & have returned,& noticed this problem.Any ideas before heading to a shop & hopefully not getting ripped off?? Oh, we have kept up with scheduled care & it has 109,000 miles on it.Thanks for the help
  • kenniekennie Posts: 38
    If you read through my previous posts/solutions my bet is that your heater core is blocked. If you have rear heat and it works but the front does not produce heat then it is almost certain that is what is wrong. If you don't have rear heat to test then a heater core flush is the only way to know forsure... you may have a manifold gasket leak getting air into the coolant resulting in low coolant and thus low volume flow through the heater core... i'm no expert but these are my observations owning the van myself (2000) with rear heat. Good luck !
  • Hello,

    This is very simple. If you have heat for your passengers seated back and cold air in front, try this: 1) disconnect the auxiliaire pump; 2) disconnct the small pipe on the other side of the motor (approximately over the belt); 3) flush in both direction with your garden hose. When the water will be clear, replug both hoses, fill it up with antifreeze and VERY IMPORTANT open the two bloods to evacuate any air that have penetrated in the system, OTHERWISE the motor will overheat while the air in the defrost will still be cold. So, check very carefully the heating temperature in your dash.

    Last point: when blooding the systems (remember there are two blooders to open), it could take you from 5 to 15 minutes to have a final result i.e. only antifreeze comes out without any bubbling.

    Think environment, use a garbage can to keep liquid off the ground. The best way to do it is to first wet the floor. While doing this any antifreeze would be very easy to wash with water, otherwise your asphalt will keep good memories of your work...

    If this help you why not consider making a donation at one of your favorite caritative organization? It can only cost you a fraction of what a garage bill is able to do...


  • I have a 2004 Pontiac Montana that I am experiencing air flow problems when you move the Climate Control to HEAT. When it is on COLD, the air flow is fine, but when you move the controller to the heat setting, you hear the air deflecting and the air flow from any of the vents up front go to almost nothing. I am not sure what is wrong. The dealership wants almost $800.00 to take it apart.
  • The issue is with the remote starter and not your vehicle. Your car has two accessory wires and both need to be connected for the accessories to function properly. Most remote starters have 2 ignition and 1 accessory outputs and if they are not connected properly your heater will not work properly. If the remote starter used to activate the heater before, check the fuses for the remote starter itself and make sure none of them have blown.
  • We dont have REMOTE Starter on the van. Again I have good air flow when the climate control is to the COLD side. When you turn the climate control to HOT, the air flow drops to almost nothing. You hear the air blowing in the dashboard, but very little is coming out of the vents.....Neither the vents on the dash or the floor board.

    If there are wires not connected I have no idea where they would be. The only remotes we have are to lock and unlock the doors.
  • kry99kry99 Posts: 1
    I have a 2005 Pontiac Montana (not SV6). This winter I have noticed more than previous winters....when you run the defroster you get air, but it never gets very warm. You can change the front to the floor and get lots of hot air, change the front to the A/C vents and get lots of hot air. There is hot air in the back for the passengers. Only on defrost do you have air that never gets warm. When you switch to defrost you can hear the deflector change and you can put your hand up by the windshield and go from no air to plenty of air coming is just not warm.
    Any ideas?
  • notaminivannotaminivan Posts: 1
    edited March 2010
    Tell me it is not true that you have to pull the dash to change the struts.
  • armesarmes Posts: 32
    edited March 2010
    No it is not true. You can reach the strut mounting bolts from under the hood. The trick to it is that you must take the windshield wiper motor and wiper assemblies off of both sides. To do this you must do the following:

    1. Remove the wiper arm assemblies from both sides. They have a plastic cap which covers the actual nut. This just pops off with a screw driver. Then remove the plastic leaf guard that is under the wiper blades.

    2. Remove the 3 nuts that hold each wiper shaft assembly. The left one will drop out. the right one needs extra room.

    3. Remove the wiper motor assembly from the right side. I believe there are 2 or 3 bolts that hold it. Pull the motor assembly forward and drop the arm assembly down as you move it forward.

    4. You should now be able to access the 3 strut nuts.

    5. Remove 2 bolts from spindle assembly and pull strut down and out.

    6. Assemble is reverse of above.

    If you are just replaceing the strut tubes and not the whole assembly, you should think about changeing the strut bearing plates on top of the struts as they go bad usually before the strut tubes. If you feel and/or hear a poping/grinding noise while turning the wheels then the bearings are bad for sure.

    If you are replaceing the whole strut assembly, spring and all, then you get new bearings in the assembly.

    Sometimes it is best to have the alignment checked afterwards as you can disturb the alignment settings.

    Hope this helps you. :shades:
  • i was changin my thermostat and i took off the throttle body the air filter as well as the hose that runs between the two.needless to say after 3 hours of fighting with the thermostat housing i got it all back together except one thing. i think its the vacuum hose on the hose that runs between the throttle body and air filter. somehow i managed to dislodge the hose and now i dont know where to put it back at. i tried to fit my hand and feel for the hole but i dont have a clue where it goes can anyone help me please!!!
  • mailmail Posts: 10
    I did the same thing... look for my postings under kennie. Now I am not an expert and if my memory serves me right (I could be wrong however) I do remember that the plastic tube that fits into the slinky air duct... the tube slipped out of the back
    of block... it just sticks in... if you clib under the vehicle and look between the rear exhaust manifold (just above) I think I recall being able to see it. Good luck...
  • ok so here we go i have a 2000 pontiac montana that was overheating i turned on the heater and it was blowing cold air.i thought that was the thermostat that was bad so i changed it, still same problem. i then notice my coolant was pretty nasty with floaties that looked like some sort of stop leak so i flushed the system, still same problem. now im thinking the water pump but i dont know how to tell if that is the solution. the whole time it was overheating the cooling fans never kicked on so could it be something as simple as a relay or do i just change the water pump and go from tellin you im gettin close to just throwin this van away.
  • sar781sar781 Posts: 3
    Someone please with knowledge help me, this vehicle has got a 3.4 lt engine, the check engine light is on, half my power has dissapeared, and theres a metalic screeching comes from underneath the vehicle when you give it gas. Also it wants to run hot because of this and I just had the plugs and wires replaced, oil changed ad new air filter put in. I replaced the fuel filter myself, that is good. Also when you give it gas you dont get much reaction from the engine, half of what its supposed to do, its got 153,419 miles on it, any suggestions????
  • armesarmes Posts: 32
    Did this problem start before or after the tune-up and oil change? :confuse:
  • sar781sar781 Posts: 3
    After the tune up, but right after I had the plugs and wires ect changed, everything run fine, its been gradually building up to this, last I checked the code reader from the dealership indicated something with the emission system ore something, cant remember.
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