# Machine gun heater **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** cherokee, jeep\ **Created:** [January 23, 2010, 4:28pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075 "2010-01-23T16:28:15Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![RobiOne](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RobiOne](https://community.cartalk.com/u/RobiOne)\ **Post date:** [January 23, 2010, 4:28pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/1 "2010-01-23T16:28:15Z")
My car is a 2005 Jeep grand cherokee 4.7 V8 with 14,000 miles. The problem is when I turn on the key there is a loud ratcheting click under the dash, lasting for about 30 seconds. I think it’s coming from the heat-A/C ducts. Is there a way to lube something to make this stop before something vital is damaged? ---
**Author:** ![ken\_green](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/ken_green/32/816_2.png) [@ken\_green](https://community.cartalk.com/u/ken_green)\ **Post date:** [January 23, 2010, 6:39pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/2 "2010-01-23T18:39:25Z")
When I put my ear up to my computer screen it sounds like a blend door motor. Heater, a/c chambers have doors in them to move the air as you’ve selected. An electric motor does this. When a door can’t move freely the little plastic gears in the motor can strip or possibly just try for a while until it defaults to off. If the motor is now bad, Why ? If a door is sticking it must be freed. If the motor is attempting to move then defaulting to off ( and not yet damaged ), Why ? Again it sonuds like a door is stuck or binding. Maybe something’s in there. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [January 23, 2010, 7:54pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/3 "2010-01-23T19:54:21Z")
Another possibility is the blower fan itself. Does it do this with the heater fan off? Does the sound vary if you start the vehicle with the fan setting at a different speed? ---
**Author:** ![Whitey](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/whitey/32/24680_2.png) [@Whitey](https://community.cartalk.com/u/Whitey)\ **Post date:** [January 23, 2010, 8:54pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/4 "2010-01-23T20:54:54Z")
You might just have sticks and leaves in your blower motor. Sometimes cleaning out the blower motor and the squirrel cage can make this kind of noise go away. If the blower motor has a bad bearing, lubricating it won’t help. The blower motor would need to be replaced. ---
**Author:** ![RobiOne](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RobiOne](https://community.cartalk.com/u/RobiOne)\ **Post date:** [January 23, 2010, 10:30pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/5 "2010-01-23T22:30:15Z")
I think you’re right about the stuck door, and the gears trying. I didn’t notice this until winter (Arizona don’t get real cold) so usually the vents are set for the upper set only. I had changed to upper and lower vents when the noise started. Now I changed that back so the noise has stopped. I just don’t know how to get in there to fix it with all the stuff in the way. ---
**Author:** ![RobiOne](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RobiOne](https://community.cartalk.com/u/RobiOne)\ **Post date:** [January 23, 2010, 10:32pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/6 "2010-01-23T22:32:48Z")
Not the fan. I’m sure it’s the vent door gears. But thanks ---
**Author:** ![RobiOne](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RobiOne](https://community.cartalk.com/u/RobiOne)\ **Post date:** [January 23, 2010, 10:38pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/7 "2010-01-23T22:38:49Z")
Car is pretty clean. 14,000 miles in 4 years. Gets about 12 mpg, so we don’t drive it unless we are going skiing. Then we need a heater. Rest of the time it sits in the garage and looks pretty. And there is no ash tray so there’s no way to tell when it’s time to trade. ---
**Author:** ![RobiOne](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RobiOne](https://community.cartalk.com/u/RobiOne)\ **Post date:** [February 12, 2010, 9:13pm UTC](https://community.cartalk.com/t/machine-gun-heater/43075/8 "2010-02-12T21:13:10Z")
So I described this noise to a Jeep dealer and while they didn’t know what it was, they were certain it would cost a minimum of $1,000 plus parts to fix it. So I took it to Tony, who said yeah he knew what it was and could fix it. Turns out it was the motor which opens the flap that sends heat to the back seat. Who knew? Required removing a large part of the dash and about 5 hours to fix it, and a $30 part. Now much quiter and much poorer. Think they may be making cars too full of useless gadgets, now. ---
**Author:** ![EllyEllis](https://avatars.discourse-cdn.com/v4/letter/e/f14d63/32.png) [@EllyEllis](https://community.cartalk.com/u/EllyEllis)\ **Post date:** [February 13, 2010, 1:26am UTC](https://community.cartalk.com/t/machine-gun-heater/43075/9 "2010-02-13T01:26:16Z")
Well I guess you found the problem. I was going to tell you that I have a blend door that must be warped and sometimes sounds that way but does work. It just drags as it moves.