I have had a problem with this car for a while. When we use the heater it does'nt blow much at all. When you turn the temp. to cool it blows much more like it is suppose to. I have read alot of posts and even cleaned the evaporator today with no change. The little air that comes out of the vents is hot when temp. is turned up and a/c works well. The coolant part of the heater core is fine but I wonder if something built a nest next to the core and slowed down air flow or something. I would like to find a picture of the hvac box to see air paths and acuators and stuff. If anyone has any ideas or pics. please help. I want to be prepared for next winter in Mn. 97 Bonnie SE

Will this be of any help to you?



Welcome to the Bonneville forum. Please add yoru cars year and trim level to your sig. This will help us when you ask for help.

That will be helpful. From this it looks like the box needs to come out. I can't see a way to get around the doors to see if there is a air flow block before the heater core. I don't think the air mix actuator would be causing this but I do plan on looking at it soon.

place the switch to work on the dash vents only... then feel to see if the air is leaking out of the other vents ie: floor vents, windsheild, anywhere else... the low pressure could be related to the actuators not opening/closing all the way and air leaking out from there... and also check the plastic molding under the hood at the firewall, where the blower motor mounts, there should be a lil hose comming off the blower motor and going into the case itself... Ive seen TONS of these, mine included that broke on the plastic case and caused a loss in air flow from the motor...

just a couple suggestions for possible air leaks

When I put it on vent or floor or defrost it only blows where it is suppose to. It just has little air flow when turned to hot temp. I will check for othere air leeks though. Thank-Bill 97 SE

The way your describing it your heater core is plugged up. That'* why your getting flow on cold, but very little on hot. Check the heater core.

Well after a year to think about it I finally took what I could apart what i could and added a few holes. When all was said and done the inside of of the evaporator and heater core were clean as a whistle. Even the mesh over the evaporator was clean. I also put in a new fan. Still when I put it in any pos. and turn from cool to hot the air flow slows way down. My wife wants to trade it in now before winter. Any other cheaper ideas wil be helpfull!

Not an idea that would help you. But does it go to max ans recirculate when you aim to the cold side. That could possibly explain the difference in air. But I can't think of anything that would cause it to be slower in heat vs ac.

One of the downfalls of any Bonneville (92-99) I've been in is the fan speed/air flow.

My Bonneville does the same thing as described above blows less for heat than AC. At first it would kick-in and out of high speed which was very noticable. Now this year its only low speed.

Does anyone know what is driving the fan. Is there a resistor pack or other electronics that may have failed?

Anyone??? Danthurs, Billboost. Sounds like ill figure this one out on my own.