Where is the windshield reservoir tank in a 2001 Chevy Malibu

Very easy. Undo the electrical connector, remove the tube, remove the bolts. Videos in the link

https://www.google.com/search?q=2018+Chevy+Malibu.+replace+windshield+washer+reservoir

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Driver side or passenger side ? Leaking heater core , windshield leaking . First you need to know what's leaking before you can be told how to fix it.

I am having the same issue. Just replaced the two hoses at the top of the recover tank (possible leak). While running at a stand still, the inside air was only blowing out cold. Let the car run for about 15 minutes to check for signs of leak and while we found none, inside heat never came on.
With in 15 seconds of pulling out of the garage, the heat decided to work

The brake fluid goes in a reservoir on top of the master cyclinder inside the firewall under the hood.

Open the hood of your 1998 Chevy Malibu and locate the brake fluid reservoir. On a 1998 Malibu, it's located on the driver's side closest to the front windshield. Open the reservoir tank and place the cap in a safe place where it won't get lost. Fill it to the fill line and not above then replace the cap and your done. Now you need to figure out where the brake fluid is going since this is a closed system and if it is low then your brakes are getting worn and more fluid is accumulating in the lines due to more travel of the brake cyclinders or you have a leak. The master cylinder should look like this picture, if you find this helpful, a vote with the thumbs up would be appreciated

What about the radiator?

usually you have to take out the inner wheel panel to access the ww

Due to the complexity of the newer cars on the raod today!! what you are experiencing is Normal!!! since the coolant systems on the newer cars run at such a higher pressure and a high Rpm the reserve tank which has it's on drain hose for excessive overflow from the radiator allows the extra high pressure release from the radiator to back flow to the reserve tank and then out the reserve tank overflow hose on to the raod

the only solution acording to the manual is to replace the reservoir... not much to say about that, u do have the option to patch it...be careful with the product u use to glue that patch.
take care

Ok... put the duct tape down. And back away from the truck... just kidding.. I wouldn't recommend duct tape. or hot glue...
If you have a visible crack or hole, drain the tank to below the crack, clean with a little vinegar and water, and lightly sand the plastic housing.
Place a small patch of plastic sheetrock mesh tape over the crack and then...
Use a bit of epoxy that is recommended for use on plastics. Mix up a small batch, spread over the crack and over the mesh.. Let dry and refill.
Don't worry about pressure, because the tank isn't under pressure on most cars...

I'm guessing you may have figured this out by now but I had to do it recently.

First drain the fluid from the reservoir. Then remove the car battery. Then the battery tray. I believe it was held on with about 4-5 bolts...one of which threads into a retainer clip on the reservoir itself. Now you have cleared the way to remove the reservoir. It is held in by a few bolts that are accessible from the top side and bottom both. You will have to get on your back and get to those with a ratchet. It will be obvious where these are upon inspection. And finally there is a plastic retainer that goes through the plastic inner fender into a retaining hole in the reservoir. Firmly but carefully separate it from this plastic retainer...you'll probably have to reuse it. After you do that the reservoir is free to move. Unhook the wire harnesses to the fluid pumps. Unhook the lines to the to pumps. Now just pull the reservoir out through the bottom of the car.

Done.