AC drain

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Apr 18, 2018
Libertyville, Illinois
Hey to all, hope everyone is healthy. I need to find the AC drain on my 83 Cutlass Cruiser wagon. Told it was below heater core box? Can't see it how to access it to unplug it? Its dripping on my rug, sure sign of a clog. Thanks all.

57 Handyman

Master Mechanic
Feb 6, 2017
Don't know for sure since I own 87 El Camino. My 87 is a 5th Gen and I believe similar/in the same generation (5th) of G bodies to which yours belongs.

Here are a few suggestions and thoughts for you to consider:

(1) Can you tell if the fluid is plain water or possibly anti-freeze? You will be able to detect a smell if it is anti-freeze. If it turns out to be anti-freeze, then the source is a heater core leak.
(2) To verify a clogged drain, I suggest you first check the bottom of the AC box in your engine compartment. If neither you nor any previous owners have done any work on rebuilding the box, that is possibly a likely source of outside water dripping into the cabin. Unfortunately, the flap over the drain is underneath and along the firewall; it is not readily visible from the top. You may be able to feel the flap and drain area from under the car.

However, the best way to do a visual check is from on top of the AC box. The G body has a screened plastic piece (3-4" x 8-10") that allows outside air to enter the cabin; the screen is visible and accessible next to the base of the windshield from the engine compartment. The screen is held in place by several screws and can be easily removed. Once removed, peer down to the bottom of the cavity and you'll likely see a lot of debris ranging from twigs, leaves, dirt, and grime that has collected over the years. This view will also give you a good idea of where your drain is at the bottom of the AC box.

Good luck!


Royal Smart Person
Supporting Member
Dec 7, 2007
Here's what the flapper door looks like on my 87 442
Drain Flapper.JPG

I also talk about it at minute 3:48 of this video.

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abbey castro

Royal Smart Person
Oct 31, 2015
Harker Hts TX
Remove bolts that hold inner fender to fender, pry down so you can stick your hand behind it and find the flap that shield the rectangular slot on the box. See the grayish flap in the picture. It is not a stiff rubber, very floppy! That is your drain for the box. You should 1st try sticking your hand between the box and the frame rail to see if you can touch it. My hand is too big and I had to let the inner fender down some to allow touching it. The Gray and Purple lines are vacuum for the HVAC system. This is for an 87MC, but should be about the same for yours.


  • HVAC Vacuum Lines at Firewall.jpg
    HVAC Vacuum Lines at Firewall.jpg
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