I had the high pitch noise coming from what I thought was the blower motor. It would get faster sounding as I switched the blower to higher speeds and it would stop if I shut off the heat system. But, the new blower motor does the same thing! Did I just get a bad motor? I remember years ago you could get a feed back in the radio when you didnt use a "choke" on the power line.
What is causing the noise? Oh, I also have the radio pulled out to make sure it is not the problem.

 

Few things come to mind here. When you replaced it did you reuse the old squirrel cage?

Also when you put it in did you clean out and make sure nothing was in the opening?

Check voltage at the wires, could be a bad switch or bad blower motor relay

if the relay is feeding too much juice it could be causing the motor to make a high pitches noise or it could also be a bad bearing int he motor

 

Thanks for the quick response ChRoNo16. Yes found the whole blower chamber full of grass clippings. Spent like 45 minutes cleaning it out, with the vacuum, blow gun, and some remote fingers to get every last bit I could find. Even used a mirror to check hidden areas. I did however use the original cage, after carefully cleaning the vanes of the cage and all sides. I thin I was real lucky finding the dead grass clippings, they were packed up against the resistor plate. I think it was close to catching fire and would have if I used it much more. I just purchased this truck and Im in the process of working out the bugs. It sat for sometime In the PO's yard near a barn. Im really surprised the bellhousing wasnt packed too.

 

I don't think it would be feeding too much voltage as the alternator seems to be very weak and the gauge is showing very low voltage being produced. Regulator seems to be fine as I don't see a drop when electrical options are turned on and off. But i do see it drop as I add up the load on the system.

 

That is probably a great place to start, I know were trying to work out a heater fan, but if we know the alternator is weak, start with what we know is wrong and see where we are after that.

 

I have a spare in the garage, I plan on putting it on tomorrow. It would be strange if that is what is causing the noise. It would really baffle the *&%# out of me.

 

I will post up tomorrow.

 

Me too, but im just going to say it, we all know cars are weird and finnicky as F***

 

Might check the weather seals arounds the doors.

A couple weeks ago on the work truck I started hearing a high pitch noise that got worse the faster the blower was spinning.

The weather strip had popped off a little.

 

Noise happens while sitting still in driveway, and with windows down.
Didn't get time to work on it today.

 

Replaced alternator, still have the high pitched whine, that goes up and down with the blower switched speed. Once turned off, no whine.

 

Must be the bearings in the new fan. it happens sometimes. What brand is the replacement?

 

Over the counter from Advance auto parts. Going to pull motor from housing and run it, see if the whine still exists. Then run it without cage if need be.

 

On my 2 GMC work trucks I've had that happen with the blower motors. If I hit the motor with something (used snow brush since it mostly happened in winter and I can reach it with the brush from the drivers seat) I could get it past the whinning, and the motor worked fine. When I got tired of doing that, that's when I replaced them. Kinda like starter motors when they're on their way out.

 

Heck, the one in there is only a week or two old. Did ever say how much I HATE CHINA and MEXICO with their garbage auto parts!