E-Bodies.org Cuda Challenger Forum

Technical Shop => Electrical & Audio => Topic started by: 750-h2 on February 07, 2018, 08:38:00 AM

Title: Testing a blower motor switch?
Post by: 750-h2 on February 07, 2018, 08:38:00 AM
I am in the process of assembling the Rallye dash on my 1970 Non AC Challenger. I wanted to test my blower switch which has 3 prongs. Two on top and one at the bottom. Using an Ohm meter I get continuity when the switch is placed on high by touching the bottom terminal and the top left terminal. I cannot get any continuity when the switch is on low no matter what prongs are touched with the probes of the Ohm meter?  Is this normal or is my switch defective?   Thanks
Title: Re: Testing a blower motor switch?
Post by: 750-h2 on February 07, 2018, 01:44:40 PM
If no one knows the answer off hand, can someone who has a switch that is out of the car be kind enough to do a simple Ohm meter test on it and let me know the results.  I suspect my switch is bad but would like to know for sure before I try to locate a good used one. Thanks!  :fingerscrossed:
Title: Re: Testing a blower motor switch?
Post by: Shane Kelley on February 07, 2018, 02:04:55 PM
I haven't replied because I don't know for a fact.  If I had a spare I would check for you but I don't think I do. But I really think you have a bad switch. I'm pretty sure you should have continuity on that terminal with the switch in a different position. I don't see how it would work otherwise.
Title: Re: Testing a blower motor switch?
Post by: 750-h2 on February 07, 2018, 02:12:11 PM
Do you know if there is a resistor in the switch.  Maybe I can take it apart and replace it?  Really wanted to put the dash pad back together this weekend.
Title: Re: Testing a blower motor switch?
Post by: Jay Bee on February 07, 2018, 03:38:46 PM
As far as I know there's no resistor inside. First pic is "FAN" (low/middle) position, 2nd is "HIGH" (far right looking from the front) position. Hope this helps, ask if you need more info. FYI, my ohmmeter reads .5/.6 when the leads are touching each other.
Title: Re: Testing a blower motor switch?
Post by: 750-h2 on February 07, 2018, 03:48:21 PM
Jay Bee that is perfect! At least I now know my switch is defective. Tomorrow I will try to take it apart to see if it can be fixed. Thanks again!!!

Title: Re: Testing a blower motor switch?
Post by: Jay Bee on February 07, 2018, 04:29:07 PM
You're welcome. I can't imagine it's too complicated inside. When I got that panel the switch was seized. A little WD40 freed it up and probably cleaned the contacts too. If you do take yours apart I'd be curious as to what you found wrong.
Title: Re: Testing a blower motor switch?
Post by: 750-h2 on February 07, 2018, 04:31:02 PM
Will do!
Title: Re: Testing a blower motor switch?
Post by: 1 Wild R/T on February 07, 2018, 05:20:52 PM
So the trick here is the old Dodge truck blower switch which while different all the important parts will interchange...

https://www.ebay.com/itm/HVAC-Blower-Control-Switch-Front-Standard-HS-203/172972000820?_trkparms=ao%3D1%26asc%3D20170105155410%26meid%3Df8fa7bb5870543ca80f5152ff51d2b8c%26pid%3D100705%26rk%3D1%26rkt%3D1%26%26itm%3D172972000820&_trksid=p2045573.c100705.m4780

Correction, looking at photos some of the dodge truck blower switches are four prong....  But some definitely were tree prong cause I've used them in the past...
Title: Re: Testing a blower motor switch?
Post by: 750-h2 on February 07, 2018, 05:25:34 PM
Thanks for the tip. Much appreciated! 
Title: Re: Testing a blower motor switch?
Post by: 1 Wild R/T on February 07, 2018, 05:39:51 PM
I updated the post.... Look close before pulling the trigger...
Title: Re: Testing a blower motor switch?
Post by: 750-h2 on February 08, 2018, 08:39:21 AM
Update: Took the switch apart this morning, just needed to bend the 3 metal tabs and it comes apart. Very simple design. Only 3 removable parts inside. I cleaned contacts with scotch brite pad, I stretched out spring to add more pressure to contact points, reassemble, then  lubed with wd40. Five minute job and now works perfectly. :thankyou:
Title: Re: Testing a blower motor switch?
Post by: 1 Wild R/T on February 08, 2018, 08:43:02 AM
Excellent!!!  Allot of the times the contacts are burned up & when that happens often the connector gets burnt too....
Title: Re: Testing a blower motor switch?
Post by: Jay Bee on February 08, 2018, 10:40:40 AM
Quote from: 750-h2 on February 08, 2018, 08:39:21 AM
Update:
.   :bigthumb: 
Title: Re: Testing a blower motor switch?
Post by: Claudia on February 12, 2018, 01:11:07 PM
Switch is a pretty simple design.  As you can see from the pictures, my switch looked to be in pretty rough shape when I started but it cleaned up and worked great!  It was a pretty easy do it yourself project!