Blower Motor Switch Wiring (AGAIN) - JeepForum.com
 8Likes
Reply
 
LinkBack Thread Tools
post #1 of 23 Old 01-16-2020, 05:47 PM Thread Starter
Jimmyj1957
Registered User
 
Join Date: Jun 2019
Posts: 58
Blower Motor Switch Wiring (AGAIN)

A while back I had some questions about wiring in a new blower motor and switch. I had a number of folks reply with very helpful suggestions and some schematics. I used one of the schematics to rewire the switch and motor. I opted to go with the larger more powerful motor when I rebuilt the heater box. I reinstalled everything and tested it out. Everything worked exactly as hoped. I turned the switch on and cycled thru the different speeds, again everything worked. Did this several times, everything was working correctly Turned it off once more and then back on again and this time nothing. Dead as can be. Thought maybe I blew a fuse, fuse was fine. Thought maybe the switch was bad, tested it with a volt/ohm meter and it appears to be fine. Installed a different switch, nothing. Connected the motor directly to the battery and it was working correctly. Tried a new resistor pack, still nothing. Checked my wiring against the schematic and can't see anything wrong. I checked the wire that connects directly to the blower motor and it was reading approximately 12 volts, which is weird because the motor wasn't turning. Its difficult to trace the wire back from the blower because it goes into a flexible tube with many other wires and is also wrapped in many places with electrical tape. Is it possible there is a "fuseable link" somewhere the wiring? Would it be simpler to just run a new wire to the blower? Looking for a couple of ideas. I have no garage so I'm outside in the cold. Man I was looking forward to having the heater work!!!!! Any help is greatly appreciated.
Jim

Jimmyj1957 is offline  
Sponsored Links
Advertisement
 
post #2 of 23 Old 01-16-2020, 06:44 PM
Spieg8
Registered User
1984 CJ8 
 
Join Date: Jun 2013
Location: Denver
Posts: 1,926
Quote:
Originally Posted by Jimmyj1957 View Post
I checked the wire that connects directly to the blower motor and it was reading approximately 12 volts... Its difficult to trace the wire back from the blower because...
If you have 12V at the motor, it's likely the motor is not grounded properly (or bad). Put a ground wire between the motor housing and the battery (-) post and see what happens. Can you measure the amperage in the circuit?
John Strenk likes this.

It's not the Voltage, but the Amperage that will kill you.
Spieg8 is offline  
post #3 of 23 Old 01-16-2020, 07:33 PM
schardein
Registered User
 
schardein's Avatar
1983 CJ7 
 
Join Date: Jun 2010
Location: Success
Posts: 901
What Spieg8 said. Build a dedicated ground wire for the blower. Put an eyelet terminal on a wire, attach it to the blower with one of its mounting screws. Scrape/sand off the paint in that area for a good connection to the blower mounting flange. Run the other end of the wire to battery negative, or at least a known good ground point.
John Strenk likes this.

1983 CJ7, 5.3, NV3550, D300 4:1, Fr D44 Ox air, Rr D44 OX cable, 4.56, 35" Falken A/T3W on beadlocks
schardein is offline  
 
post #4 of 23 Old 01-17-2020, 04:53 AM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 21,127
What those guys said.

This is exactly what I had to do however since your heater box is already mounted. You could try using a bigger ring terminal and attach it to one of the heater box mounting bolts. on the firewall.

Also 12 volts at the terminal with just the volt meter is not the same as 12 volts with 10+ amps to back it up.
Need to check the voltage with the motor attached.

You could also run a jumper wire direct from the battery to the motor to see if it works that way.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #5 of 23 Old 01-17-2020, 07:57 AM Thread Starter
Jimmyj1957
Registered User
 
Join Date: Jun 2019
Posts: 58
Well, the motor is installed and partially visible thru the firewall like normal. I attached a jumper wire from the (+) side of the battery directly to the blower motor and it run full speed, so wouldn't that indicate that it is properly grounded? I've studied the schematic that was posted on this forum and if i remember my electronics theory the resistors in the resistor pack just drop the voltage going to the blower to slow it down or speed it up. For instance, when the switch engages the position that would be slow speed, the current travels through all the resistors to drop the voltage the most. Next position, the current would go through less resistance, and finally high speed bypasses all the resistance in search of (ground) to complete the circuit. Is this correct? As I mentioned in my original post the PO had just snipped off the wires going to the switch and I hoped and prayed that I found and made the proper connections. On my Jeep there is a lone TAN wire that connects to the blower motor under the hood. Under the dashboard one of the wires that had been cut was TAN. I assumed that they were one and the same. Still, I will try to run a dedicated ground wire. Any other ideas ?????
Jim
Jimmyj1957 is offline  
post #6 of 23 Old 01-17-2020, 11:38 AM
Spieg8
Registered User
1984 CJ8 
 
Join Date: Jun 2013
Location: Denver
Posts: 1,926
The battery (+) is probably pushing 500-600 Amps or more, that may be enough to overcome a questionable ground where the 5-15 amps going thru the regular circuit may not.

If you measure the amperage in the circuit that will tell you if you need to look into the wiring. If for example you measure 12V but only at 1-2 amps, that would indicate a wiring/ballast or switch problem. Just trying to save you from cutting into the harness if you don't have to...

It's not the Voltage, but the Amperage that will kill you.
Spieg8 is offline  
post #7 of 23 Old 01-17-2020, 12:33 PM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 21,127
Plug the wire from the switch onto the motor and measure the voltage with a DVM and see if it still gets 12 volts when it's turned on.

That's one of the troubles with a DVM. You can get fooled. Because a connection can show 12 volt if it has 0 ohms resistance or 10,000,000 ohms resistance.
One will work one will laugh at you...
OrangeCJ-5 likes this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #8 of 23 Old 01-17-2020, 12:40 PM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 21,127
The fire wall connection is in the picture below. Position CY

80-86-bukheadconnector.jpg

This is the backside of the fuse box.

backof84fusebox.jpg

You can check the voltage there also.

Check voltages with everything connected.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #9 of 23 Old 01-17-2020, 10:09 PM
Cutlass327
Web Wheeler
 
Cutlass327's Avatar
1978 CJ5 
 
Join Date: Jan 2009
Location: Beach City
Posts: 6,867
When I bought my CJ, the PO had drilled a hole in the motor where it was in the engine bay area and used a sheet metal screw to attach a ground wire to the motor housing. It may save you from having to remove the heater assembly again, but I would suggest some protective paint or something over it to keep it from rusting. When I replaced that motor, I just used a mounting screw and ran the wire out the hole with the motor, connected straight to battery.

Rick

1978 CJ5 5.0HO/T177/D300 TerraLow 4:1 kit, '86 D30/D44 3.54 WT axles w/Aussies, 'glass body, 33x12.5 ProComp A/T, TDK galv'd frame, 2.5 OME YJ lift - DD and weekend toy


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Cutlass327 is offline  
post #10 of 23 Old 01-18-2020, 07:59 AM
Dryseals
Registered User
1980 CJ7 
 
Join Date: Apr 2010
Location: Texas
Posts: 1,482
I'm not real familiar with this resistor pack, but from looking at the pictures of one they have a Thermal Fuse Cutoff built in just like on the TJ's and they are notorious for blowing. Even on a brand new one they can pop easy and they are dirt cheap to produce so most won't last very long either. I ended up soldering a wire across it because I could buy a new one and it may last for a few days. I did some research on these Thermal Fuse Cutoffs and there are a ton of variations. Main specs are going to be temperature and current, so you can get one for 16 amps but is rated at 212 deg C or 10 amps at 121 deg C and all kinds of varieties in between. Since the wiring worked but doesn't now, that Thermal Fuse Cutoff I would bet is the problem.
Attached Images
   
Dryseals is offline  
post #11 of 23 Old 01-18-2020, 09:07 AM Thread Starter
Jimmyj1957
Registered User
 
Join Date: Jun 2019
Posts: 58
I will investigate all these possible solutions. It's probably a ground issue. Just irritating that it worked and then suddenly quit for no apparent reason.
Jim
Jimmyj1957 is offline  
post #12 of 23 Old 01-18-2020, 11:04 AM Thread Starter
Jimmyj1957
Registered User
 
Join Date: Jun 2019
Posts: 58
One additional thought/idea I had. Before I remove the heater box assembly to see if the motor is properly grounded. I have a spare and tested blower motor that I was going to use in this project but I went with the larger motor. If I connect this motor and make certain its grounded properly and if it functions correctly, would that confirm that the issue is grounding? I'm also concerned that the plug connecting the motor may have some issue (seems loose to me).
Jim
Jimmyj1957 is offline  
post #13 of 23 Old 01-18-2020, 09:21 PM
Spieg8
Registered User
1984 CJ8 
 
Join Date: Jun 2013
Location: Denver
Posts: 1,926
It would confirm the issue is ground or a bad motor... Hope you didn't cook the motor by direct wiring to the battery (+) post.

Why do you insist on jumping to the difficult tasks right off the bat? As I originally suggested, I'd connect a ground wire between the motor case and battery (-) post before tearing anything apart (unless you just enjoy pulling the heater box, or tearing into the wiring harness for the fun of it). You'd literally just have to touch the wire to the battery (-) post and motor case for a second (while the fan switch is turned on high and the ignition is in ON position) and see if the motor turns or not (what could be easier than that?).

The wire terminal is just a spade connector. If it is loose, you can just squeeze it a little with some pliers to make it fit more snugly.
Cutlass327 likes this.

It's not the Voltage, but the Amperage that will kill you.
Spieg8 is offline  
post #14 of 23 Old 01-19-2020, 04:11 AM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 21,127
Quote:
Originally Posted by Spieg8 View Post
It would confirm the issue is ground or a bad motor... Hope you didn't cook the motor by direct wiring to the battery (+) post.

Why do you insist on jumping to the difficult tasks right off the bat? As I originally suggested, I'd connect a ground wire between the motor case and battery (-) post before tearing anything apart (unless you just enjoy pulling the heater box, or tearing into the wiring harness for the fun of it). You'd literally just have to touch the wire to the battery (-) post and motor case for a second (while the fan switch is turned on high and the ignition is in ON position) and see if the motor turns or not (what could be easier than that?).

The wire terminal is just a spade connector. If it is loose, you can just squeeze it a little with some pliers to make it fit more snugly.
You can not hurt the motor by directly wiring it to the battery..
schardein and OrangeCJ-5 like this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #15 of 23 Old 01-19-2020, 07:37 AM Thread Starter
Jimmyj1957
Registered User
 
Join Date: Jun 2019
Posts: 58
Because, I don't want to risk damaging the motor by drilling into the motor housing to attach a wire. If I have to remove the heater box again, "so be it". Its gonna be done the correct way. The previous owner(s) "half assed" everything that's why I'm dealing so many issues. But, thanks for the suggestion. If touching a wire to the motor housing solves the problem, terrific, I know what I gotta do. Also the (+) connector is so old and brittle it will likely brake if I try squeezing it. It will definitely be replaced while I'm at it. Again, thanks for your help.
Jimmyj1957 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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 Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome