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Vans & Minivans Pontiac Montana Pontiac Montana Heating / Cooling Problems
44 messages, Last post on Dec 06, 2009 at 1:40 PM
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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
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Replying to: kennie (Oct 04, 2009 8:11 pm) 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 |
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Replying to: kennie (Oct 04, 2009 8:11 pm) 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. Yours. Carfixer4u
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Replying to: carfixer4u (Nov 14, 2009 12:12 pm) 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. Kennie |
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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
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Replying to: 2009sv6 (Nov 27, 2009 6:39 pm) |
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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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Replying to: chamkake (Nov 30, 2009 3:21 pm) 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... .
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Replying to: spike99 (Dec 06, 2009 9:20 am) 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. |
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