BillBoost, I agree with you and Randman 100 percent. IF it is a single air system, the temp coming from both sides 'should' be more equal.

Bill Buttermore, thanks for the info. I checked the label on the spare tire cover and it has C61 in the first row, next-to-last column. There is no CJ2 number in the list. Assuming the label is correct, guess that means I have a single air system. Wouldn't think that though, from looking at the FSM airflow drawings and pondering the symptoms of the problem.



Thanks for the help, Guys. Really appreciate you.

Jim

talked 2 different people on this subject! the tech that reflashed my PCM thats works at the dealership. and another tech also . he said they have seen a blend door crack ; fall off. get stuck . obstructed heater cores. that would cause this . he printed me out a gm service bulleting for heating insufficient on my car. and also temperature control motor circuit description . and a Air distribution system description.{ 5 pages} both agree that the dash would have to come out to research and fix this! will try to get to junkyard and do my own research . 22 degrees here in ohio now . sorta cold to be hanging out in the junkyard. thanks everyones help . will keep you posted. Tim

hey guys, after driving my pickup for a couple of days (the heater works GOOD in that...) i finally got a chance today to tear my dash apart and fix the heater!

There are 2 things that I did while i was in there, i'm not sure if it was a combination of the 2, or if one was the actual solution and one didn't matter... anyways they both involve the heater core! ...kind of.

I had to remove the glovebox, and i also took off all of the trim on the dash panels, and the lower dash piece which is held on with 10mm head screws. i removed the programmer, and the end cap of the heater box which is just behind the programmer (passenger side). with this panel removed you will be staring at the heater core! it is held in with two 7mm screws and the heater hoses that are out under the hood going through the firewall. I took the screws out, removed the hoses, and took the heater core out of the car. After much snooping around, testing, scratching my head, etc... I came to the conclusion that either the heater core had to be plugged in some of the fins, or the gasket around the heater core was leaking, allowing cold air to bypass the heater core and go directly to the ducts! I flushed the heater core out pretty good and some chunks of "crap" came out. not a lot, but i suppose it could have possibly plugged some of the orifices. Then I put the heater core back in the car (without hooking up the hoses), and turned the fan on high! i felt around the heater core and felt that air was in fact coming through where the foam "gasket" was supposed to seal it in place!!! This would allow cold air to bypass the heater core and go straight through to the vents! Not that much air was leaking, and it actually looked like it fit pretty good, but I took that foam gasket off and put new foam strips on there just to be sure! After flushing the core, and replacing the foam gasket, i put the car back together just to the point that i could test it out. I left it in the driveway running until it warmed up, and when i got back into it...SURPRISE....HEAT!!!!!!!!!!!

It'* a bit of a pain, and it took me about 4 hours from start to finish. Now that you know what you're looking for it should be a little faster. I have pictures of what I'm referring to, and I also have more replacement foam gaskets. email me @ fordsucksme@yahoo.com for more information.

I should also mention that i found a red herring during this process! The heater box on the engine side has a note on it saying something to the effect of "to remove barrier cut here" and there is a molded line in the plastic! Well, mine was CUT! I think someone replaced the evaporator before i got the car. Anyways, i thought maybe this was where the cold air was leaking in from because there was no sealant used when it was put back together, just a big slice in the heater box! But upon further investigation from the inside and outside....it turns out that'* just a cover and no air could get in through that slice. Good luck guys!

Jim - thanks for humoring me. Now at least we know what it isn't!

89sse. Congratulations! Nothing better than to be warm when it'* cold. I am hoping you have found the solution for everyone. Am I right in assuming your fix was on a '91 Park Avenue? And does that car have the single system?

And... yeah, I noticed that "cut here to remove blower motor" on my heater box insulating cover on the '95 SLE too. But you don't have to cut anything to remove the blower motor. Gotta be for some other GM application.

Yes that fix was on my '91 park avenue, it had the DUAL system. BUT, after seeing how this system operates, I don't think the dual or single part had anything to do with it. I think even with a single system if you had the same type of air leak that I had (allowing air to bypass the heater core on the lower rear corner), it would feed cold air directly into the ducts leading to the driver'* side. I say this because I have a hard time believing there would be completely different ducting for the different options. i'm thinking you either get dual with 2 actuators, or you get single with one actuator controlling both doors. Maybe someone here can verify this? i haven't taken apart a single system... I don't know if there are 2 mix doors that are connected or just one big door. I do know that my dual system uses the same pivot point for both air mix doors! In fact, if you move one mix door, the other door moves with it because they are both on the same rod, UNLESS you hold one door in a different position. I think the foam tape they used to seal the entire heating system just gets old and deteriorates and doesn't seal so good! NEW SEALS FOR EVERYBODY! sorry it'* not something simple to perform! you pretty much have to take the heater core entirely out to do this correctly. I guess you could try leaving the heater hoses connected (they're a PAIN to get off!, at least on the park ave) but you wouldn't be able to get to anything but the front side. That may be all that is necessary, but i figure if you're already that far, you may as well go the extra step and MAKE SURE it'* fixed! i really cannot believe how little of an airleak made this huge difference in temperature! it baffles me!

I believe the "cut here" line is for access to the evaporator. It is deep within the heater box!

Hi all,

I'm experiencing these EXACT symptoms on my 1996 Bonne SSE. I see that a fix was posted for a Park Avenue (with the same issue) but no one confirmed that it was the same fix for the Bonneville. Was that the final resolution for the problem?

Any help is appreciated.
Thanks.

yes, that was indeed the final solution! the heater has been working EXCELLENT ever since! i have not had to tear apart a bonneville heater box THAT far yet, but i can tell you that from the outside they look IDENTICAL. the blower motor controller is the same, everything is in the same position. i would imagine it is the same exact setup. but instead of splitting the driver/passenger doors in half and making 2, they just left it 1 big door. i can't help with gaining access through the dash, i'm not sure exactly what would need to be removed in the bonneville. the park ave was relatively easy because there is an entire lower dash panel that unbolts pretty quickly. start behind the glovebox, you need to remove that end panel on the passenger side of the heater box to gain access to the heater core! good luck!