Fan flutter noise with air conditioning on

Hi Daniel You mentioned a noise but not what type of noise?
I can only give some ideas of the more common noises.
1 fluttering noise, normally a leaf or leaves have managed to enter box from external vent.
2 squeaking noise, dry bearing or worn bearing.
3 whirring noise, again possible bearing.
4 movement when switched off scraping or scratching sound possible mouse has got into box again through external vent.
5 buzzing or ticking noise possibly electrical fault do not use until checked by auto electrician.

note, most cars have a cabin filter between the external vent and the intake fan, normally these filters are not to difficult to access with care. If it is accessible remove it and check inside with a mirror and torch. Good luck

See if you can find the exact location of the noise.
When you replaced the blower, did you clean out the plenum all the way back to the air inlets? There is some play in the blower bearings which can cause rubbing when starved for air. Also, could be rubbing on debris in the plenum.
Another possible cause of this noise is a fluttering damper. Depending on the HVAC option you have, the mixing and duct selection dampers may not be opening/closing properly. If they are vacuum actuated, there may be a leak at or in a control solenoid or the switch. Try all temperature and vent settings to see if the noise changes. If they are working properly and the noise continues, then it's usually a blower problem or not the HVAC system making the noise.

Sounds like a bad bearing in the transfer case

Well son, there are MANY reasons that might cause "fluttering" in your gauge. Mine started doing that, then I started getting a warning LIGHT for overheating. My solution for that was a fault in my fan. There are 2 speeds on my VUE'S electric fan. The one that required attention was speed/high (the speed/low was working). If your getting an intermittent short, watch both the temperature and fuel gauges to make sure it's not a real (both will do the "fluttering at the same time if it's faulty short) overheating problem. If you have an OCD-2 reader, plug it in under the driver's dashboard and go to function "live" read the engine temperature. If that's normal it will be between 120F-200F.
Faults may be relays in the under-hood fuse panel (there either good or bad, you can't see anything like other fuses) and there are the 30 amp or 10 amp fuses inside the same fuse block for that electric fan.. I've found that if I open the hood and start your car, after it warms up, there are tree things that could happen.
1: the low fan starts up, then start your A/C, the high fan speed comes on (normal, check your temp gauge).
2: After you warm it up, the low speed fan starts up, but with the A/C on, the high speed fan isn't coming on (bad high speed fuse or relay).
3: after warm up, the low speed fan doesn't come on, but starting the A/C the low speed fan comes on (bad sensor I think).

I've had a ghost in my VUE since I bought it, gone through 3 computers, CVT sensors, key won't turn without destroying the key. One time, I used the horn to get some deer off the road and the damned thing wouldn't shut off. While I was under the hood trying to get it to turn off, TWO cops stopped, they shined their flashlights on the fuse block and one on the diagram for me to pull the right fuse. I took it out, plugged it back in and it worked again! The shop didn't find a thing wrong with it, but the thing works still.s

Sounds like the blower motor...at low speed it makes the noise due to motor or blower wheel out of balance or something in the blower housing

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/sean_54c3a3dc48a7773c

Obviously, you are talking about your vintage 1932 Chevy Coupe. I know that's the vehicle because you did NOT say that it WASN'T!

The fluttering sound is probably dry leaves that got stuck in the blower assembly! Suck them out with a shop vac!

most caddilacs have a filter under the wiper plate that filters out all the junk leaves and debris. first thing is to make sure the coolant is full, as the high temps make liquids dissapate. once you have done this, then I would check the restricted fan, or possibly the fan resistor, this resistor controls the amount of voltage to the fan and gives you multiple speeds.

Try checking fan belt.Thank you for asking and I hope this helps you.Please leave me a 4 thumbs up.

I believe you may be referring to 'pinging', Try a tank of premium gas and see if it stops. Check your timing, and when was it last tuned? Let me know what u find. countrycurt0

I just repaired my 02 Galant with same problem. I removed the heater control box and disassembled and applied 12 volts dc and verified motor was ok. Then attached the plug back on and checked in car still not moving. Removed the screw holding the temp. control and cleaned contacts and applied pro-gold contact cleaner and preserve re-assembled and heater works like a chame. Saved 400-500 bucks and we have heat. About 2 hours labor to remove bottom part of dash and troubleshoot.