Blower Motor mystery - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-24-2003, 06:15 PM
Registered User
 
Join Date: Nov 2003
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Blower Motor mystery

I hope someone can help me out here, cause this fault is driving me crazy.

My heater blower stopped working on all three speeds about 3 weeks ago without warning. My car is a 1994 Ford Escort. It does not have air conditioning.

Today I finally got round to taking the thing out, and what a job that was. I bought a replacement unit (motor and resistor) from a scrap yard thinking everything would be okay after a straight swap, but when I connected it all up, it wouldn't work either.

I have checked the multi-connecter going to the resistor on top of the blower and it is receiving 12v power on all three switch settings. I have also carried out an ohm test on the resistor and it appears to be okay - the ohm values were something like 0.05, 0.16 and 0.25 (decimal point may be in wrong place). The motor works fine when power is applied directly across the terminals.

When I put it all together though, it doesn't work. What is strange though, is that when I put a volt meter on the "out terminal" of the resistor with the power switched on, I get 12v only until I ground the motor, then it goes to 0v. I take it this is not normal?

Any idea what the problem could be?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-24-2003, 06:17 PM
poncho62's Avatar
Out of the Loop Moderator
 
Last wiki edit: Streetbeasts links
Last journal entry: at car show
Last photo:
Join Date: Oct 2003
Location: Hanover, Ontario, Canada
Age: 62
Posts: 16,857
Wiki Edits: 5

Thanks: 20
Thanked 246 Times in 200 Posts
Sounds like the motor that you got is shorting out.

Any sparks when you ground it?
__________________
Ontario Rodders
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-24-2003, 06:21 PM
Registered User
 
Join Date: Nov 2003
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
There are no sparks when I ground it.

The thing is, I have also tried the other motor from the scrap yard and tried interchanging the resistors to see whether it makes any difference, but the exact same problem keeps reoccurring.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-24-2003, 06:22 PM
poncho62's Avatar
Out of the Loop Moderator
 
Last wiki edit: Streetbeasts links
Last journal entry: at car show
Last photo:
Join Date: Oct 2003
Location: Hanover, Ontario, Canada
Age: 62
Posts: 16,857
Wiki Edits: 5

Thanks: 20
Thanked 246 Times in 200 Posts
If you have 12 volts coming to the motor, it should turn. There has got to be something wrong with the motor.
__________________
Ontario Rodders
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-24-2003, 06:27 PM
Registered User
 
Join Date: Nov 2003
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
But both of the motor's turn when power is applied directly across the terminals. Could it still be a fault with the motors even though they work in this fashion, bypassing the resistor?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-24-2003, 06:30 PM
poncho62's Avatar
Out of the Loop Moderator
 
Last wiki edit: Streetbeasts links
Last journal entry: at car show
Last photo:
Join Date: Oct 2003
Location: Hanover, Ontario, Canada
Age: 62
Posts: 16,857
Wiki Edits: 5

Thanks: 20
Thanked 246 Times in 200 Posts
If the motors turn, they are OK. It must be your resister, or the way the resister is wired up.
__________________
Ontario Rodders
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-24-2003, 09:26 PM
akm akm is offline
Member
 
Last photo:
Join Date: Mar 2003
Location: USA
Posts: 431
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
94 ford escort.
all i have to say about that car is, you better hope that your heater core NEVER goes bad.
when i worked as a mechanic, one of these ***** jobs came in, and i got to looking at it, and couldn't figure out how to pull it apart. so i hopped on the service computer and printed out full details on how to do it.
glancing over the list i read the words "and now remove the dash".
long story short, i had to remove the entire dash and lay it in the front seats in order to get to the GD heater core.
to this day, that was the second biggest pain in the ***** job that i have ever done on a car (took 2 days)(oh and the first was a clutch job on a crane).
just thought i would share.

later Aaron
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-24-2003, 11:04 PM
Pony's Avatar
Member
 
Last photo:
Join Date: Sep 2003
Location: Lynnwood, Wa.
Age: 67
Posts: 721
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It sounds like your saying that it works on the bench but not when installed in the car. If so, does the motor base have a ground tab on it somewhere. Most blower housings are fiberglass or plastic and the motor assembly needs a chassis ground ( usually a black wire) to complete the circuit.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-25-2003, 06:31 AM
Registered User
 
Join Date: Nov 2003
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The motor is in a plastic casing an has a ground wire running from the motor to an earth point on the car.

I went and bought a new resistor today to try that, but it still doesn't work. So now I know that I have a working resistor and a working motor and that I have a live feed from all three settings on the switch, but it still won't work?????? I have also tried earthing the motor directly onto the battery to make sure it is not my earth connection at fault, but the damn thing still wont work.

I think the fact that I have a live feed across the resistor until I connect the motor's earth wire up must be pertinent to solving the problem, bearing in mind that this occurs on both motors I have tried.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-25-2003, 12:57 PM
Pony's Avatar
Member
 
Last photo:
Join Date: Sep 2003
Location: Lynnwood, Wa.
Age: 67
Posts: 721
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I don't have an electrical diagram for that model but it almost sounds like you have a Diode in the circuit. A diode only lets the current pass in one direction. It's used to protect circuits from damage by feed back and shorts. Is it possible that you are plugging the resistor Assembly in backwards? Troubleshooting electrical problems over the Internet is scary at best because one mistake can cause a lot of smoke and money, so, a trip to the electrical shop may be your only alternative. Good luck.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 11-25-2003, 01:30 PM
Registered User
 
Join Date: Nov 2003
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The resistor assembly can only go one way, and I was very careful when I took everything apart to note how it all went back together again.

Could it be possible that there is a fault in the motor itself causing the problem, even although it works when jumpers are connected direct from the battery? The only thing with that theory though, is the improbablility of two different motors having the same problem (albeit the other motor was obtained from a scrap merchant).
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 11-25-2003, 05:18 PM
Registered User
 
Join Date: Nov 2003
Location: NH
Posts: 2
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
My daugher has a 1990 Toyota Camry. The heater fan and power seatbelt both stopped working at the same time. There was a blown fuse and we replaced it. We reset the circuit breakers. The fan and seat belts are still not working. We have purchased a new blower motor but have not installed it as of yet. The old motor as in the post above works off the battery. We thought there may be a relay problem. Should we try the new blower motor or replace relays.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 11-26-2003, 10:43 AM
Wrencher's Avatar
Member
 
Last photo:
Join Date: Aug 2003
Location: cincinnati
Age: 56
Posts: 607
Wiki Edits: 0

Thanks: 5
Thanked 0 Times in 0 Posts
Not real sure I want in on this, but, sounds like your losing the 12v feed under a load, check all the 12v feed connections, even the switch! If your getting 12v to each resist. term as you switch speeds, what is the voltage coming off the resistor? The high speed should bypass the resistor! With everything plugged in, work backwards till you find 12v!
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 11-26-2003, 11:09 AM
Jag Daddy's Avatar
British Style with USA Muscle
 
Last photo:
Join Date: Mar 2003
Location: Valencia, California
Age: 57
Posts: 1,078
Wiki Edits: 0

Thanks: 7
Thanked 0 Times in 0 Posts
Here's a trick, you can check voltage drop across the ground. Put your meter on the chassis of the car and the other lead to the motor gound if it's open you'll read 12volts. That will tell you if you have a proper ground to the motor.

Regards
Mark

Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 11-26-2003, 09:16 PM
Kevin45's Avatar
Just one of the guys
 

Last journal entry: Garage Toys
Last photo:
Join Date: Jul 2002
Location: Urbana, Ohio
Age: 57
Posts: 3,058
Wiki Edits: 0

Thanks: 1
Thanked 15 Times in 15 Posts
If the motor works when wired direct, your switch is bad. Replace it and it should be fine.

Kevin
Reply With Quote Quick reply to this message

Recent Electrical posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 03:40 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.