| Author |
Message |
    
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 770
Registered: 11-2002
| | Posted on Tuesday, May 30, 2006 - 9:58 pm: | 
|
Ok, this isn't new this is a reoccuring issue with all of us here, well some of us.
I've been having terrible A/C luck lately and today didn't give a break from it either. I'm too fat to be ridin' around with no A/C, and the diet pills I take now keep you pumped up and hot all the time.
Anyway to get to the point, I was outside this afternoon working on my A/C. The truck has this blower motor resistor thing that mounts into the A/C box under the hood and has a thermal fuse on it. It keeps blowing that fuse and costing me 40 bucks a pop. I'm on my 5th one now, but maybe I've figured that part out.
Suffering from the RFI or EMI which ever one it is, has been driving me crazy also. If you turn the A/C blower off low, you get this terrible hum or grind or whatever you want to call it in my radio. I know it's caused by it, cause unhooking the antenna makes it go away. So it's coming in that way. I had taken the blower motor out and removed a vent tube from it. I looked inside and it has brushes inside it.
My question is do the motor with brushes cause more problems like what I'm having over the other type of motors? I figure the antenna is picking up the popping and static/hum from the brushes on the shaft. How could you stop that or block it from the antenna picking it up? I grounded the blower motor to the chassis, but that didn't help any. The control has 4 positions, low then two more and then high. From the second setting to high it gets worse the faster the motor turns.
Would wrapping it in grounding strap and grounding that to the chassis help the issue, using it as shielding? |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1243
Registered: 6-2004
| | Posted on Tuesday, May 30, 2006 - 11:54 pm: |
|
A bypass capacitor or feed through filter capacitor would eliminate the interference. It totally eliminated it from my car's blower motor. The feed through filter would have to be rated to handle the current used by the blower motor. The ones I use are rated at 40 amps. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 772
Registered: 11-2002
| | Posted on Wednesday, May 31, 2006 - 8:08 pm: |
|
I remember you telling me that, but what about it using brushes instead of being like a regular motor?
You don't think the antenna is actually picking up the discharge at the brushes? What you're saying is it's being sent back down the wires?
Where did you say you got yours at? You have a link or something? |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1247
Registered: 6-2004
| | Posted on Thursday, June 01, 2006 - 10:04 am: |
|
I don't think the brushes make any difference. The RF is traveling back up the power wire and radiating from it just as it would an antenna. The closer you install a filter to the motor the less noise you'll have.
I got mine at Radio Shack years ago. I don't think they've been in their catalog for a while, so you probably can't find any in stores unless you get lucky. The item number was 272-1085 and it was called a Feedthrough Filter Capacitor. The catalog says it contains a 60v .5 microfarad capacitor, and you connect it to the power wire with threaded screws/nuts on either end. They work very well.
You can just use a .5 microfarad capacitor of at least 16 volts and get the same effect connecting it from the power wire to ground as close to the motor as possible. Inside is even better if you can manage that.
If you can't find them and aren't willing to try just the capacitor, there are commercial filters that do the same thing, they're just more expensive than a couple of capacitors. The Gold Line 1090N is an example of one. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 774
Registered: 11-2002
| | Posted on Thursday, June 01, 2006 - 3:19 pm: |
|
Well I sure appreciate it. Getting inside isn't going to be an option though. It's liked pressed together and at almost 100 bucks for a stupid blower motor, I don't want to ruin it. It stinks you have to buy everything for that truck from the dealer.
I will try what you've said, cause it stinks
not being able to hear things I can with the A/C turned completely off. I surely appreciate your time and effort. The A/C was broke two days this week, the blower resistor that is, so I was just riding with the air blowing through the system. I could hear so much more than I can since I fixed it yesterday afternoon.
Thanks Hollowpoint! |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1251
Registered: 6-2004
| | Posted on Friday, June 02, 2006 - 9:40 am: |
|
I hope it works as well for you as it has for me. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 842
Registered: 11-2002
| | Posted on Sunday, July 02, 2006 - 9:29 pm: |
|
Update:
Got the filter and tried it on each lead going to the blower motor. Still have the problem. I have even lowered myself to wrapping the blower motor with aluminum foil, heavily. Trying anything to stop this annoying noise.
I've added grounding and I just don't understand where the noise is coming from. It's affecting the receive of my radio, especially if I turn the blower fan up very high. Low, Med, Med High and High are the settings on the switch. And at low you can hear it, but not a lot. Med you begin to hear it a bit more and the last two it's just about all you can hear.
Now moving the filter and wrapping the motor seemed to knock it down a little bit, but not completely out, which is what I want to happen.
Just for the record incase somebody reads this and has another suggestion...this is my setup:
Magnum S9, dash mounted. Grounding strap from the case to the cab of the truck. 12ft jumper from the radio to the Davemade box. The Dave is mounted to an aluminum channel bolted between the passenger seat rails. The rails are bolted to the floor, but I added grounding strap as well. 14.5 foot of LMR-400 Ultra Flex from the Dave to the triple mag mount with a Predator 10k mount and antenna on it. Extra ground strap is ran from the cab to the chassis. Radio & amp are ran straight to the batteries, one on one battery and the other on the other battery.
All grounding strap was added to try to eliminate the noise, it didn't change anything either and the noise didn't increase either.
Do I need to put another filter on the other wire for the blower motor? Is the problem elsewhere in the system and not at the blower motor?
I appreciate any and all help...thanks! |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1285
Registered: 6-2004
| | Posted on Sunday, July 02, 2006 - 11:58 pm: |
|
Looking at the schematic you sent me, it appears that there are two power wires that go to your motor - one for full speed, and one for reduced speeds that comes from the resistor network controlled by the speed switch. Unfortunately because both wires are connected to the motor at all times the RF radiates from both wires and you will need two filters for the blower motor - bummer!
Of course if you're adventurous you can pull the motor, open it up, and place a capacitor across the power wire(s) to ground inside. That's probably not an option for anyone who invested what you have in your vehicle.
It also appears that the motor is grounded to the chassis because there isn't a ground wire on the schematic. Wherever the motor is grounded is where the filters should also be grounded. |
Milkman21218
Member
Username: Milkman21218
Post Number: 63
Registered: 1-2004
| | Posted on Monday, July 03, 2006 - 12:08 am: |
|
Kevin,I had the same problem in a few(Fords my van and Semi).Couldn't stop it in the tractor until changing alternator. Also had to do the same on a Mack. A filter worked on van. I wonder is it a Diesel BIG TRUCK? If so it could be the same problem. |
Im4jc
Intermediate Member
Username: Im4jc
Post Number: 155
Registered: 11-2005
| | Posted on Monday, July 03, 2006 - 1:24 am: |
|
Porkchop, I have the exact same problem in my KW W900L. You crack me up, I also thought about covering my blower motor housing with aluminum foil, lol. Well, I fixed the problem. It's still there, but much better anyhow. I ditched the S9 and got a Grant LT...MUCH better noise blanker than the S9 especially after replacing the NB diodes with NTE 583's.
There are still things that I miss about the S9 though...mainly the daily flowers that came my way. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 843
Registered: 11-2002
| | Posted on Tuesday, July 04, 2006 - 12:53 am: |
|
Yeah, you ever saw that movie "Signs"? Where those kids are on the bed with those big foil hats? My blower motor looked like that this morning. It didn't help...not one bit. The blower motor has a small duct running to it for air, so if I wrapped it in cement it wouldn't over heat.
I thought of taking it apart...but it's one of those that is pressed together. If I open it, I doubt I could put it together again. I'm too fat to be ridin' around all day with no A/C...10-4?
Yah...this is my BIG TRUCK...come on. Well, my only truck cause it cost enough without me adding another truck to my checking account right now. This problem is getting to be annoying. I will fix it...oh yes...I will fix it.
I can not find nary'a place it's ground HP. Except maybe like I said through those little clamps that bolt to it and bolt to the A/C lines. Maybe that is where the ground is coming in from? I was thinking today though...and came up with this..well this and a headache from thinking:
I don't know how it -was- grounded but I know how it -is- grounded now. Now let's say that the noise is actually through the ground side and not the positive side of things. Since it's only effecting the CB and not the stereo, could it be because the antenna is a mag mount and it's picking it up through it's wanna be ground system? Do they make a filter for coax, the signal coming in, not a transmitting filter---I know they make that.
I've emailed Sterling about this...for sure I'm not the first person to have this problem with one of their trucks. Don't get me wrong...I love my truck...I really like Sterlings...but I wish more and more I'd went with my first pick...a KW. Metal doors are hard to beat. The T800 would have been a nice truck..the WL9 is a real nice truck...but I'm a wanna-be Super Trucker and that hood is too big for me...
Well I'll order another filter...or better yet I'll unhook one side and just run the filtered side. Wouldn't that work? Just to see if it stops it? |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1291
Registered: 6-2004
| | Posted on Tuesday, July 04, 2006 - 4:09 pm: |
|
I guess it would work!?! I don't think it could harm it, so it won't hurt to try it.
To be honest, I don't know why there are two power wires. What're really got me second guessing is that you were holding the blower and it was working. The only ground possible at that point would be the wires, but looking at the schematic those wires are both power wires. Odd. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 849
Registered: 11-2002
| | Posted on Tuesday, July 04, 2006 - 7:06 pm: |
|
Yes...agreed. At that point where I removed it from the housing and it started up, I thought one wire was positive and the other negative. But looking at the schematic/wiring diagram...blows that out of the water. It is clearly marked that they are both "hot" wires.
Could it be that it is like series and not parallel wiring? Maybe the ground is actually at one of the relays or something? I can't figure out how to extract the photo from Adobe to post here for someone else to look at.
I'm thinking maybe the noise is being emitted into the metal of the cab and the antenna is picking it up there, through it's capacitive ground. But I've grounded the triple mag mount before and it didn't seem to change anything. I know for sure it didn't help SWR, I didn't actually check the A/C system...but I remember while having it grounded I heard the noise. Not sure if it was more or less though, just remember hearing it.
I still lean toward the brushes in the motor making static or something from them discharging against the rotor or stator or whatever it's called. But I thought shielding it with it's little "foil hat" would have stopped it or atleast made a dint in it.
I don't mean to beat a dead horse...but this is very annoying to me. It makes receiving distance weak signals nearly impossible. I am at the point to where I will pay someone to fix this, no matter the cost within reason. |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1292
Registered: 6-2004
| | Posted on Wednesday, July 05, 2006 - 2:09 am: |
|
Does it only operate at full speed when it's not mounted? It could be that it's using the resistor network as it's ground path - it does have a connection to ground.
The brushes are definitely where the noise is coming from. If you could use a bypass capacitor right there you could totally solve the problem, but you'd have to take the motor apart to do that. When you get the second filter installed you should have a great deal less noise. |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 856
Registered: 11-2002
| | Posted on Wednesday, July 05, 2006 - 6:17 pm: |
|
I know I sure hope so. Thanks.
If I don't...I'll just burn the dag-on thing...how about that?
OH...no I know what I'll do. I'll get another style blower motor and then I'll wire it up on a 3 position toggle and make my own control for it...haha.
See...the eye of a mind makes a movie... |
Navyrebel782003
Intermediate Member
Username: Navyrebel782003
Post Number: 226
Registered: 12-2004
| | Posted on Wednesday, July 05, 2006 - 9:32 pm: |
|
Hey Porkchop, send me a copy of your schematic and maybe I can see where the ground is at seeing as how I am used to reading those things for F/A18's, I'm sure your truck cant be that much more in depth...LOL.
James
CEF#590
CVC349
Va Beach |
