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Pontiac Montana Heating / Cooling Problems



  • hi kenni

    i have an o2 montana, been having heater problems as well like everyone else that owns one of these vans. my van does not have a rear heater will it still have an aux. heat pump, this morning it just blows cold air and is now over heating it is full of coolant. and when u turn the knob to change it from defrost to floor or vent u can hear it changing and it blows plenty of air it is just cold air instead of hot . my husband thinks it is the thermostat sticking causing it to over heat but u have to take the top part of the motor apart just to gret to the housing . i am really tired of this . do u have any ideas thanks
  • kenniekennie Posts: 38
    edited December 2011
    I am no expert and can only provide recommendations from experience. I have a feeling there are a few potential problems from more likely to less likely: plugged aux pump (if you have one), medium head gasket leak, minor head gasket leak, plugged heater core, interior heating vent door not operating properly. Your motor is not overheating it is not the thermostat.

    Can't remember the last messages i've posted but I was able to get heat back by flushing (myself) the heater core... of course in the most environmently friendly way - probably more-so that any garage would spend the time to do - see my previous posts on this. Lots of crap came out of my system and i figured I had the problem fixed. I took appart and cleaned the aux pump as it was completely blocked - another reason for no heat. I blead the system of any air, replaced the thermostat (but this is not really related to the heater core in this case) and bob was my uncle... best heat ever.

    About 4 months later, I started getting rough idling... and could smell antifreeze.... I knew right away my head gasket let go and stopped running the van immediately. The cost to have my head gasket replaced (including new radiator - because I pull a ski boat with my van 3000k/yr on holidays) was around $3000 at a local shop. That explains why I was getting air into my system in the years previous causing overheating, poor fluid flow, limiting heat, etc. but it must have been minor enough that I did not see antifreeze in the oil or smell antifreeze in the exhaust so I didn't know.

    If your motor is overheating your head gaskets might be going and causing air to enter your system not allowing the fluid to flow. This is major problem with this van, BUT there are things you can try before going down this road. Just keep an eye on the oil (look for brown color - signs of antifreeze in oil) and smell of antifreeze in exhaust. The exhast will show signs of white/grey and if this is the case don't run the vehicle... you'll bend your push rods or damage your shaft and then your motor is pretty much toast. This could be a cause of overheating. Second reason is a failing thermostat.

    1) run the vehicle and monitor the hoses going to/from the heater core - do they heat up? Is the return heater hose from the core heating up just as fast?

    2) Unless your vehicle is overheating, this is not a cause of your heat in the van but, release any air you have in your system using the two pins (one on tube coming out of water pump and the other near the thermostat housing while the vehicle is idling. Be careful, you just want the air to escape, not the fluid. See how much this helps, notice how much air comes out... if there is allot it could be a head gasket leak.... but if you clear it and then the air eventually comes back, you'll know. 3) Might be worth changing the thermostat. If you don't have alot of patience, this is a real pain in the [non-permissible content removed] and probably I would not do this again myself. But if you are taking it in for this then maybe you should have them do a diagnosis

    3) If you have an auxillary pump (from the sounds of it you don't), lookup pictures on the internet for location. It is a magnetic motor driven pump at 10oclock of your antifreeze overflow container on RHS of the vehicle compartment... you can't miss this as it has a couple wires going to a sensor between the bumper and the rad. I cleaned mine and it was horrid... don't think any flow was getting to the heater core and is the only route to get there. I have given instructions for this in previous posts as well. If you do this, you might as well do #4 too.

    4) use my proceedures to flush the heater core.... see my previous posts and i have given detailed instructions how to do this being highly environmently friendly. If your heater core is truely plugged, you will know because you will be able to tell what the flow is when you flush it.

    Final comment:
    These are ONLY suggestions based on my experience. If you want to save yourself some headaches after bleeding the system of air first and it does not help the heat, I would book an appointment to have your heater core flushed and your aux pump cleanned. My feeling is that your thermostat and pump and potential gasket leaks have little to do with the heat in your van if your van is not overheating. It is a pretty simple thing, there is likely no fluid flow through your heater core or not enough to allow you to get any heat. If you put the blower on the lowest spead and the engine is running at operating termperature you should feel some heat... if you feel none after some time it is either flow problem or a door is stuck... I highly doubt a door is stuck but again, i'm no expert... I can see the door binding and not fully closing or opening - this is possible. The vents work on air presure so if you hear them moving you should know they are working.

    If GM came out with a new extended pontiac montana van I would buy it in a second. Yes, i've replaced head gaskets but it is the most versitile vehicle on the road as long as you are willing to be constantly fixing things - no more than any other vehicle in my opinion. Good thing about it is that it keeps running and I can pretty much fix everything myself if i'm feeling broke to save dealership prices. If you are not that way then this van could be a money pit for you.

    Keep us posted on what happens !
  • I am having an issue with my 130,000 mile 2006 Montana not sharing its heat. The van does not over heat and is running at a normal operating temperture. It will give off a little heat and three seconds later blows cold. For awhile it would give off warm when you were driving and it would go cold at stops. It has even stopped doing that. Serpentine belt broke two months ago and replace it. Just replaced the EGR valve and the cat. I also had to replace the fan knob that got broke. Any Ideas I am thinking maybe thrmostat, or a blockage in the heater core maybe?
  • kenniekennie Posts: 38
    You can see my other posts on this... there are quite a few. But based on what you are telling me I would guess that there are two aspects to your problem -maybe a third. I've experienced EXACTLY the same thing with this van. The head when it is cold out -15bones is not great even right off the factory line - so you can't have a high expectation off the starting line. If you are rear heat and the vehicle is purchased in canada or cold climate area then it probably has a auxilary coolant pump. It is located inches from the front/left corner of the coolant reserve when you are facing the vehicle. The pump is actually a motor with a magnet that drives a fan that pushes fluid into your heater core and to the rear heater core. If you have one of these they get bungged up... my van is a 2000 and this was my problem... the fan was no longer turning and was completely bungged up... your van is a 2006, I can't imagine this happening so soon but it is possible. I flushed my heater core myself and cleanned the aux pump and all was well - i have extensive posts on Edmonds on what I did number kennie. If your motor is not overheating then I cannot see what a thermostat change would do to help... it is already opening/closing if you are not overheating. The only other thing could for you to add coolant or bleed air out of your system using the two pins... possibly you are not getting enough flow but I doubt this would cause your low heat issues. When I sped up the engine I had more heat... this would explain that you are not getting enough fluid FLOW through your heater core... thus the aux pump or core bockage. When I flushed mine (both ways) allot of debris came out. Good luck.
  • kmongerkmonger Posts: 1
    I am not sure when this issue has started as I don't run the a/c when I drive. My husband does when he drives. We are pretty sure we have a leak but can't find it. Any suggestions?

    Also, when we put freon in it gets cold and blows cold air out the front but blows hot air out the back. Does anyone know what is causing this? Please help we need air in the back for the 4 kids. My husband touched a pipe or hose on the bottom of the van while he had the air on and it was really hot. Any idea's or help please!
  • reikureiku Posts: 2
    ok last summer I hade a radiator that the trans. cooling lines cracked and trashed the trans. I had the trans rebuilt and the radiator replaced as well as the fan assembly. I had not issues at first but after a couple of months I started having problems with overheating. I assumed since the hoses had not been replace that I was loosing coolant and would just add. Now about 3 months ago I noticed that I had what appeared to be a rust colored back flow into the overflow res. Now recently the van started overheating again and i noticed that there was poor flow of liquid. I replaced the thermostate. Oh yes it is hard to get to thermostate but I removed nothing but the hose and used a wrench on the back bolt. So yes it is possible with patience. Anyway, I still had issue. I did not know that the system needed to be bled. I was traveling the next day down the road after replacing the thermostat. It overheated so i pulled over and turned of the engine. I waited several min trying to let it cool enough to get me home since I was a couple of miles out. I could not get it started. after several attempts and almost an hour a gentleman stops and got it started. I got home and turned it off as soon as i stopped moving in my drive. I let it cool and started the engine and was in the process of trying to bleed the air out. The engine started making a wierd noise and was shooting water and air out of the radiator opening. I quickly shut the van off. I waited till the next day and now the thing will not catch. I know I get spark and gas as it tries to catch but will not stay running. I have read several post but have not seen someone post the same problem. Any ideas? Thanks Lisa
  • My 02 montana sat for 6 months i got it about a month ago, havent ran it that much, but changed the coolant, thermostat, and now it over heats, have bled it and everything, was fine for a week or so, started it up today and its over heating and white smoke is coming out the tail pipe, went away after 20 mins, now when i say over heating it doesnt red line but comes close to it. also have given it an oil change, havent seen anything or smelt anything different in the oil. signs and people have said head gasket is this the case or should i try something else. would hate to pour more money into it then i already have!
  • I am not totally familiar with the Montana van per se, but I do know that 2006 was the time frame of the evil Dexcool engine coolant. There is a class action lawsuit that has now expired that speaks to the chemical reaction of this coolant when heated and exposed to atmospheric air for a prolonged period. ie: as when the coolant level has become low. The material turns gelatinous and can stop up the heater core and other critical cooling hardware. It happened to me when engine service was being performed. The other reply has the person diligently flushing out the cooling system and replacing it with some of the more excellent non automotive manufacturer producers of coolant. The global coolant has superb all-around properties and compatibility. You may wish to convert to better coolant.
  • I have a 2002 Pontiac Montana that will not switch from heat to A/C. I have been able to run A/C all summer but when I switch to heat, it blows luke-warm air. Then when I switch back to A/C, cold air comes out of the upper vents but the lower vents still blow warm air for a while. This started happening last winter - couldn't switch from heat to A/C because I wouldn't get cold air. Finally got the cold air from the A/C but now can't switch back to heat. Initially the level 5 on the heating fan switched stopped working and prior to that I would have to turn the heating lever all the way to 5, would hear a pop or click sound, and then it would switch from A/C to heat. Could this be the problem (not being able to get to level 5) or could it be something else - interior heating vent door perhaps?
  • Just a update to this post .... I have finally figured it out. Just recently, the Hear/A/C control center on the dashboard started to act up. The different levels for blower speed started to not work. Then I smelled an electrical burning smell...finally the blower stopped working and the knob for the blower speed selector broke. I went to the salvage yard and picked up a control unit for a 2001 montana and installed it.....NOW I HAVE GOOD AIR FLOW!!!!!!!!! GM could not even figure this air flow problem.......

    This raises some serious questions about the safety of the wiring harnesses in this car. I have had to replace the rear break light assembly due to the houseing burning out. Now I find this on the heater control center. The fuel gage does not work properly...This too is noted as a electrical problem.....UMMMMMMMMM
  • Montana van 2001, front heater fan, little air flow, but lots of noise from fan pushing air. You can feel the heat coming from the heater core. One person said, its the motor, that drives the doors. Fortunately, I have some air flow for the front defrost and heat in the rear to warm the van. I am told I have to take the dash apart to fix this problem. This van has a number of electrical (wiring short) problems when the van runs through water. The radio stops, the LED lights for the parking, fuel guage, fail to work. When the van dries out in the warm sun in Saskatoon, everything starts working again. When the weather gets warm in Saskatoon, maybe in May! I will crawl under the van, to seal the wiring which is shorting. Same with the front head lights, which I also read, allow water in because the sealant fails after 5 years. I just used silicone to fix a failed drivers window. For me, as long as the van engine runs, the front wipers and lights work all that electronic can fail. I am surviving without have lots of air flow in the front heater, don't need the traction control, ABS, radio, etc.
    I have to admit, that I like having a van fully loaded with temperature guage showing me, its -1C outside, because thats when the road is most icy. Driving in Saskatoon is a real challenge with all the potholes, and ice. I will feel a real loss when this simple temperature monitor fails.
    For all you reading this threads, I found it useful to call the GM dealer. I had a very serious problem with my brakes freezing. A guy at the dealership in Saskatoon recommended I take my van to the heated garage on 1 Avenue, to dry out the brakes. I found another trick. I bought a propane torch which I used to heat the rear brake drum. I then sprayed in a small hole in the brake drum cleaner. This worked every time. Obviously, when the weather gets warmer, I will take the drum off, and clean and repair the brake shoes. I bought this Montana van for $1,000, and if I can fix these minor problems, I will have a great van, to get to work. My last comment is about replacing the spark plugs. Apparently, it costs $400 because of the cost of removing the alternater etc to get at the 3 spark plugs at the rear of the engine. I tried to find a YouTube video on this. Anyone know.
  • JJallen07 comment was very useful, as on my Montana 2001, the van switch failed completely this week, but then started again. Also, my radio light failed yesterday so I hit the dash, and the light came on again. Obviously, all the connectors in the dash, are dirty (0xidized), and need cleaning or replacing.
    Its great, you can go the local auto wrecker and find the replacement for the heater and AC wiring and replace it.

    I also, had the rear tail brake light socket melt and fail. I put in a new bulb and cleaned the socket. Again, dirt and oxidation of these sockets cause heating and melting of these parts. Thats why quality components have GOLD plating to avoid these oxidation problems. Even having nickel alloy contacts would be an improvement. When we buy a vehicle, I don`t think anyone asks this question of the dealer, what kind of electrical connectors are on the brake lights, heat lights, signal lights, as these are critical components. As long as the vehicle passes the 100,000 kilometer warranty, that is sufficient. Personally, as I fix wiring which does not operate at -50C with silicone wiring, I see this stuff, as a challenge. You know, its a cheap crapy designed wiring, but how, can it be fixed to last another 2 or 3 years when the engine craps out.

    Thanks for jjallen07 comment, as I will be going to the local wrecker to fix my AC heater control. It would be nice to know, what you payed for the part....
  • I was wondering if anyone could tell me how difficult it would be to replace the a/c suction hose. I am a shade tree mechanic and mechanically inclined enough to do this. Do you have to pull the radiator out to do this?
  • Did you ever find out what the problem was? I am having the same problem.
  • meghan101meghan101 Posts: 2
    the regulator valve for the vaccum you got one in the front and one in the back it the one in the front was clogged but we replaced the one in the back which was still good so we switched them and it was working fine, the other part was the radiator hose was not long enough. my van is not totaled because 2 days before xmas a tree landed on it.
  • di_adamsdi_adams Posts: 1
    I recently had some work done on my van. I have not had A/C for over 5 years so I thought I had better get that fixed (new condenser). While working on that, the mechanic called and said that the radiator had a bunch of small holes in it. Okay - put a new one on. The A/C works great - I didn't realize how much I had missed it! My problem is that now it overheats - sort off. I took it back to the original mechanic and he thought it was the thermostat - Okay, put a new one on. It is still overheating! It will be running fine then all-of-a-sudden PEGGED! I took it to a second mechanic and he bled the lines and it worked great for a day. What could be causing this?
  • thehawk62thehawk62 Posts: 1
    I have a 2009 Montana SV6, and the AC doesn't work. The AC LED on the HVAC dash panel doesn't illuminate when pressed, nor does the system work on the MAX AC or defrost settings. Also the rear defroster won't work, which may or may not be related. Replaced the dash HVAC control panel - same problem. Replaced the BCM under the left side of the dash - same problem. Could this be as simple as low refrigerant? Any ideas? Vehicle has been to a mechanic, what's next? Thank you.
  • Has your mechanic checked the actual temp of the van while it "overheats"? I ask this only because my temp gauge was pegging out as well however with a scan tool plugged in it showed that the computer was right at 194 or so. the real problem was the gauge and not the van over heating. to have the dash fixed can be very expensive and GM is known for having the little stepper motors go bad in the dash. Thankfully I was able to fix it my self for much less than any other option. I noticed it most when I had drove the van until it was warmed up then turned it off for a short time and turned it back on. another way to diagnose this is if the temp gauge does not drop to zero when the van it turned off.
  • Owner's Manual Page 6-16: Passenger Compartment Air Filter Replacement.
  • wholmwholm Posts: 1
    I read the article and the discussions you have posted for the no heat and I would like to tell you what I have done and what I could possibly missing that has not fixed the problem.
    I put on new head gaskets, new timing chain and gear along with rear crank seal, new plugs, wires, thermostat and now a MAP sensor. I have taken off the heater core hoses and put a hose up to it and flushed the inlet and watch the water come out as fast as the water pressure going in. I did not open it up full blast and flush but it seemed the water was flowing sufficiently.
    I then did the rear hose the same way. I put them all back on, I started the engine after I topped it off and then bleed both bleeders. Is there a sequence to doing that. Both spit a little air and then antifreeze came shooting out if I open it far enough.
    When the car is hot and the cooling fans are running I turned on the heater inside, front and back. Bleed the bleeders again. NO HEAT. I touched the inlet to the heater core and it is warm, not hot. What am I missing or did I do something out of sequence or wrong?
  • I have 2000 Montana overheats changed therastat tried to bleed it won't work no heat but van overheats
  • KCRamKCRam Mt. Arlington NJPosts: 3,516 is against the forums rules to post your phone number. Posts are visible to the entire internet, and we can't protect you from malicious use.

    KCRam - Pickups/Wagons/Vans+Minivans Host
  • Hello,
    I have a 2000 Montana and have experienced many of the same problems. Just under a year ago, I had the condenser and related parts replaced as my a/c quit blowing cold air. Even after this, I continued to have problems, so mechanic bypassed heat (I live in Florida, so not a huge issue for me). Everything worked fine for a while...My problem now is that the front a/c stopped blowing. It is still getting cold (as I feel it come through vents when I'm driving) and the rear still blows. Any ideas what I should check???

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