Heater/AC Groaning - 76 Thunderbird

[BigDaddy66]

Hi Guys-
I have a weird issue with my heater and AC. Whenever I have my heat or AC turned on, when I accelerate the car while driving I hear a groaning noise. If I am maintaining speed - there is no noise. When I have the heat or AC turned off I have no noise.

I thought it might be that air was in the heater core, so I topped off the radiator - but I still get the groaning. Any ideas?

Thanks in advance!

[mcm51]

After reading your post thought I'd add this if it would help...my '85 GT broke a heater core, took it to the dealer(car was 4 years old) they replaced the heater core gave the car back to me and every time I would squeez the throttle a little I'd get this strange noise coming from the core area...so I took it back the next day, they had it for a couple hours, I drove it home, no more strange noise, got home, popped my hood to look things over and found how they fixed the noise, they had put a worm gear clamp on one of the rubber heater lines just in front of one of the heater core nipples and had it cranked down a little restricting flow in or out of that new core fixed my problem.......so with that in mind maybe you should fire it up, pop the hood and have someone squeezing on those lines a little while someone is throttling up the motor and see if that changes anything.........just a thought.....