Ecto Cooler was a flavor of Hi-C juice. It was a 1987 product tie-in between the juice company and The Real Ghostbusters, which was an animated cartoon based on the 1984 live action movie ‘Ghostbusters.’ The juice turned out to be way more popular then the cartoon, and the cartoon went off the air in 1991, while Ecto Cooler could be seen on shelves until at least 1997 (or later; see below).

Now, even though Jeff may argue this, the formula for Ecto Cooler is not, in fact Candy Apple Cooler. In fact, I could find shockingly little information on CAC, but did find out the dirt on Ecto Cooler.

This blag gives the full run-down, along with a link to the teaser commercial for the product (that’s right, Ecto Cooler had a teaser commercial), but basically, orange lavaburst is not similar, but he heard rumors that a Hi-C flavor Shoutin‘ Oranger Tangergreen (which has a green-lips mascot looking similar to Slimer) may be the same formula as EC. The guy did research. One really cool fact is that receipts when purchasing SOT would ring up as Ecto! That suggested that they reused the Ecto UPC. In the end, he did prove, as much as one can, that Shoutin‘ Oranger Tangergreen is the same formula as the wildly successful Ecto Cooler.

Lastly, the Hi-C wiki states that Slimer left the box for Ecto Cooler in about 1997, but the product existed until 2001, when it was renamed Shoutin‘ Orange Tangergreen and:

In 2006, Shoutin‘ Orange Tangergreen was renamed Crazy Citrus Cooler.
In 2007, Crazy Citrus Cooler was discontinued. The formula to make the Ecto Cooler and its counterparts is no longer made. Though the flavor is basically a combination of oranges and tangerines.