Got a 1999 blazer LS with a 4.3L its a good blazer but it has a few issues.

First off the AHL's are always on they come on as soon as I turn the vehicle on. Its weird because I can't control the lights on the **** that selects on off or drl .

Nextly the heat works but it doesn't blow that much it just makes a whistling/whining noise.

And also there is also this odd rattling from the dash when im not pressing the gas.

 

What are AHL's?
Common problem for the light switch to burn-up. Will need to be replaced; easy to do.

The whistling/winning sound you are hearing is very likely a vacuum leak at the HVAC control panel. Usually the rotaty swtich will need to be replaced, also easy to do.

 

Thanks my man. And ahl is automatic head light. I have no idea where the vacuum line is

 

There is no AHL that I am aware of; there are DRL = Daytime Running Lights and if the your '99's are controlled the same way as in my '02 Blazer: press the Dome Override button in/out 4 times. This will turn the DRL off until the ignition switch is turned off. Then the DRLs are reset and will come on again.

If you do not want the DRLs on, remove the fuse in the compartment under the hood, driver's fender.

There is a vacuum line that goes to the rotary **** in the HVAC control panel. Requires removal of several trim panels to get to it and might have to remove the floor console as well. Again all easy to do....but I have done this many times. Just need to remember where the screws go...and there are two different sizes/types.

 

I just can't stand the headlights being on continuously and me not being able to turn them off. They come on as soon as I turn the key on

 

Pull the DRL fuse in the underhood fuse panel. That will eliminate the daytime running lights.

 

Cool thanks

 

Jatkins, when you say the headlights are on, are they the low beams or the high beams? are the parking lights (bumper lights) on as well as the tail lights?
if its the high beams and nothing else, then that is the DRL. if its the low beams and everything else, then its the AHL. the sensor for the AHL is on the passenger side dash speaker grill. if you have something on top of it, there is your problem. if you dont, then the sensor could have gone bad. if you do a search for it, someone on here figured out what diode you need to keep them off.
and pull the DRL fuse out of the fuse box i have heard leaves you with only 1 high beam. so you might want to check that too.

 

1. The low beams and the front and rear running lights you mentioned come on as soon as I turn the key on. I don't want this because I buy expensive bulbs and they r always on.

2. Now I need to find the ahl sensor

 

as i stated, the AHL sensor is on the dash, passenger side speaker grille. if you have something on top of it, such as a few pieces of paper, a dash mat, a baseball hat, ect. then you have found your problem. if there is nothing on it, then your sensor could be bad.

the powers of search will help you greatly!!!!!
Here is what you need.