I'm having an issue with the heater in my car. It seems to always be on.

With the console set to off and at 60 degrees, during any sort of acceleration it bleeds REALLY HOT air into the cab through the defroster and floor vents. If I put on the AC, it also blows really hot before getting cooler.

It seems to me that air is constantly blowing around the heater core, and I know in the past this is always attributed to vacuum line failure. but I've checked miles and miles of vacuum lines under the hood and behind the dash and they all seem fine.

I know some other people seem to have had this problem in the past by doing a forum search, but nobody got a solution.

You need to remove the glove box liner to verify the blend door is opening and/or closing fully as the display temp is changed. Dial up 60 degrees and the metal threaded rod and arm should move towards the firewall to close the blend door. 90 degrees should move the rod towards you, opening the blend door, raising the fan speed and the temperature of air coming out in the auto position. Ck the ribbed finger diameter hose connected to the blend door module. Make sure its not kinked and connected at both ends (dash and module) If all thats OK, then ck for vacuum at the heater valve. I believe? that vacuum closes the valve and no vacuum allows it to open. So, at 90 degrees setting should be no vacuum to this valve. At 60 degrees, there should be vacuum. If no vacuum at all, back trace the vacuum hose. Getting warmer air as accellerated usually means a vacuum leak somewhere. I think this car has a vacuum storage canister behind and below the passenger inner fender? Is that hose off, kinked, cut? Report back.

I haven't had time to inspect the issue yet, but oddly enough it seems to have stopped, leading me to believe that it's not a vacuum leak, but rather an electrical issue.

I still need to take out the glove compartment and give the blend door a look. I had no idea it was right there, thanks for the info.

Upon further inspection, it seems the vent is activating properly, although it does so rather lethargically.

Vent? if you mean the blend door rod moves slowly, then thats normal. It should move slowly and smoothly. Is the ribbed hose OK?

The ribbed hose seems fine, the problem seems to have completely gone away. I'll be on the watch to see if it happens again. I'm thinking there may be a problem with the climate control panel. It gets a little wonky from time to time.