hvac issue...please help.
 

Hey guys, Im new to this site. very helpful site I may add. My girlfriend has a 98 bonneville with like 238k miles on it. I've been trying to keep up on it so it doesn't break down on her. anyway, she is having a lot of hvac issues with the car.

First issue that started was this past winter. at any random given time the heater would not work when she first turned on the car. Usually after about 10-25 mins after the car being on, the heater would finally kick on. After making it through winter with this issue, summer time came. The same type of deal was happening with the AC, accept when it actually turned on I noticed it was only coming out the defrost and floor vents. After reading around on this forum I found out about the vacuum leak from the "collapsing nipples". I spent a few hours 1 saturday dealing with this issue and was able to fix it. the AC started blowing out the vents!!!....

...After about a week or 2 of fixing the vacuum leak I noticed that when the AC was on high, it would randomly loose flow through the vents. I manually turned the fan from high to low then back up to high and that would fix that issue for a little bit. But it continued to do this and I would have to manually turn the fan from high to low and back to high...

...after about a week of this my girlfriend tells me that the AC has completely stopped working, so today I was in her car and I started playing around with the controls. I turned on the AC while car was on, and I could hear everything clicking and engaging (atleast thats what it sounded like to me). but no air was coming out of any vents what so ever. tried turning controls up and down, high and low, but nothing I did would allow any air flow at all....

I have been reading around about other peoples issues with hvac, but haven't seen any issues exacally like this one...My first thought is the motor...or maybe some sort of switch, I know quite abit about cars, but have never messed with automatic climate control system.

SO...after you read this long book, if you have any suggestions at all I would appreicate it ALOT...also if you suggest something, please give me a little more detail than "check motor" or "check switch"...I wouldn't know how to check things like that without an explanation..


Thanks a lot for your time!

Sounds like you are on the right track. The blower motor is located in the engine bay on the firewall. First thing I'd test is the wiring to it. check for power and ground. If both exist, it would appear the motor is bad.

You might want to check the fuse. Since the vents are working it may not be the fuse but if it is you don't want to overlook it.

ok, so I need to check for power and ground to the motor itself...and if I have power and ground the motor is bad???....I assume I do this when the car is running with the AC on??


also...There is no air flow anymore inside the car...I wouldn't suspect the fuse...but I will check it just to rule it out...but being a rpr tech at a credit card company I know fuses don't blow by them selves...

...so this weekend I will test the motor and re check the fuse...if these 2 are good where else would I look? Thanks for the replies so far!

So you have no airflow anywhere. Do you at least hear your fan blowing or trying to blow. Its possible you have a bad blower resistor. A bad blower resister would cause no fan speed resulting in no airflow.

Also have you checked all your grounds?

https://www.gmforum.com/t278980/

Also what AC control system do you have? Do you see 3 knobs or a digital display with buttons?

EDIT

ACC...................ok

that is correct, no air flow at all..to be honest im not really sure about hearing the fan or not, I haven't messed with it enough to hear all sounds, with my work schedule its hard to work on it during the week. saturday I will be taking the car to my dads to do some testing on it, and just wanted to get some good ideas from people who own these cars and deal with these kinds of issues on a daily basis.

from what I gathered I need to check the motor for power and ground - if have both its bad

re check the fuse

check fan to see if its actually spinning - if not then it may be a bad blower resistor?

also check the ground bus under driver/passenger side floorboards - clean if dirty


I think this will give me a head start this weekend! Thank you guys for the help, if you have any other suggestions please feel free to let me know! Once I get this figured out I will let you guys know exactally what was wrong. Thanks again