Loud noise when blower is on after hitting bump
#1
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Year: 1996
Model: Cherokee
Engine: 4.0
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When I have my blower on and hit a bump or turn left sharply,even close my door, there is a loud humming/grinding noise. It is more sensitive the on the higher speeds. As soon as I turn off the blower it stops and the is a very faint click noise.
While is it making this noise, If I lower the blower speed the noise just becomes higher pitched. Any ideas? how hard to fix? Pics?
While is it making this noise, If I lower the blower speed the noise just becomes higher pitched. Any ideas? how hard to fix? Pics?
#5
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I know this is an old thread, but I'm reviving it because I'm having the same issues. With one exception... This is happening AFTER I put in a new blower motor AND resistor. Today I replaced the both parts. As soon as I fired it up I got a humming/grinding noise. The noise get's louder when traveling over bumps, and stopping abruptly. It sounds like something is loose jamming things up in there. Though I was very careful not to let anything drop into the blower housing.
I now have heat. On the lowest speed (1) the noise starts, when I crank it any higher it makes a loud squealing chatter with some funky smells. When it hits 3 - 4 (speed), the blower just stops working. It really sounds like something is in there pressing on it, or the blades are rubbing on something (resistor maybe?).
Upon removing the old resistor i noticed some melting on the connector, which I'm lending to the old blower motor for pulling (or putting out) too much power. The connector seemed to be in decent shape overall however.
I thought about pulling the resistor or and running the motor dry with the resistor housing open, going around to the firewall and wiggling the motor around to see if maybe it's seated improperly.
Any thoughts on this or common occurrences?
I now have heat. On the lowest speed (1) the noise starts, when I crank it any higher it makes a loud squealing chatter with some funky smells. When it hits 3 - 4 (speed), the blower just stops working. It really sounds like something is in there pressing on it, or the blades are rubbing on something (resistor maybe?).
Upon removing the old resistor i noticed some melting on the connector, which I'm lending to the old blower motor for pulling (or putting out) too much power. The connector seemed to be in decent shape overall however.
I thought about pulling the resistor or and running the motor dry with the resistor housing open, going around to the firewall and wiggling the motor around to see if maybe it's seated improperly.
Any thoughts on this or common occurrences?
Last edited by KJamesJR; 12-08-2013 at 07:47 PM.
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Having kinda the same issue myself. Blower motor was extremely loud and chattery so I took it apart today and the motor was FULL of cobwebs, dirt, hair, and anything else you could imagine, cleaned it out with brake cleaner and air and boom quiet as can be. I have also lost every speed but HIGH and smelled melting plastic the other night but none of my connectors look like they've ever been hot, inspected all connectors and cleaned all switches today....
#7
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You can take a look at part of the blower fan through the glove box opening. See pic below.
Select off (O) on the AC-Heat control panel mode selector, select #1 on the fan speed.
Roll the glove box down by removing the rubber stops.
Look in at the recirc door inlet. You should be able to see part of the blower fan. See if there's any crap around the fan. You may be able to nudge the fan with a screw driver through the recirc door inlet and see if its free to turn.
Select MAX AIR - recirculation on the mode selector and turn the ignition key to ON (run) without starting the engine. The fan should be turning on low speed. increase the speed and check for your noises, crap flying around in the fan chamber, etc.
Pic of the recirc air inlet through the glove box opening.
Select off (O) on the AC-Heat control panel mode selector, select #1 on the fan speed.
Roll the glove box down by removing the rubber stops.
Look in at the recirc door inlet. You should be able to see part of the blower fan. See if there's any crap around the fan. You may be able to nudge the fan with a screw driver through the recirc door inlet and see if its free to turn.
Select MAX AIR - recirculation on the mode selector and turn the ignition key to ON (run) without starting the engine. The fan should be turning on low speed. increase the speed and check for your noises, crap flying around in the fan chamber, etc.
Pic of the recirc air inlet through the glove box opening.
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#8
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I'll give this a try tomorrow afternoon. Hopefully I don't have to pull the entire blower motor out again. That was worse than my exhaust manifold swap. I REALLY hope there's nothing wrong with my new blower motor. It was clean and spinning freely (no noise either) before I installed it so I don't see a DOA being an issue.
Thanks again CCKen.
Thanks again CCKen.
#9
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Solved my issue.
The new blower motor I put in was off centre. I loosened the screws and turned the battery on to let the fan blow as I re-angled the blower motor in the housing. I pushed it down literally a few thousands of an inch (maybe .050" - .1" or so) I then stopped hearing rubbing. I tightened down the mounting screws and tested again. The rubbing came back. I then eased the top mounting screw off a bit (maybe a 1/4 turn) and the motor straitened out. The rubbing stopped. Now hopefully this fixes my resistor burn out problem. No more noise though. Clean quite flowing heat. I'm amazed they made the tolerances on the blower motor housing so tight, a simple gasket would have sufficed.
The new blower motor I put in was off centre. I loosened the screws and turned the battery on to let the fan blow as I re-angled the blower motor in the housing. I pushed it down literally a few thousands of an inch (maybe .050" - .1" or so) I then stopped hearing rubbing. I tightened down the mounting screws and tested again. The rubbing came back. I then eased the top mounting screw off a bit (maybe a 1/4 turn) and the motor straitened out. The rubbing stopped. Now hopefully this fixes my resistor burn out problem. No more noise though. Clean quite flowing heat. I'm amazed they made the tolerances on the blower motor housing so tight, a simple gasket would have sufficed.
Last edited by KJamesJR; 12-11-2013 at 09:56 PM.
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