A/C - Heater Fan issue...

[ShelbyDogg]

Green gets power from the ACC-Yellow plug when the key is on.  It connects to the blue wire which energizes the Compressor clutch when you push the A/C buttons. Didn't think you needed those because you stated that you had a fan issue.

[mapandjlp]

Green gets power from the ACC-Yellow plug when the key is on.  It connects to the blue wire which energizes the Compressor clutch when you push the A/C buttons. Didn't think you needed those because you stated that you had a fan issue.

Ok, thanks.  Just curious.   

[ShelbyDogg]

As you can see, when Heat is pushed, you should get voltage to the brown wire, through the resistors, then to the blower at low speed. Moving the fan switch to MED and HIGH bypasses resistors to speed it up.

When using MAX A/C and A/C, power comes from the BOTH the TAN AND BROWN wires, the fan speed switch supplies voltage to different parts of the resistor tree. 
    You might have to cut open the A/C control, then drill it then screw it back together or just replace it, if it is still available.
 




I had to edit this text above because I cut open my switch to see exactly what position the contacts were in for the different settings.

[mapandjlp]

So, I'm thinking I'd like to replace the vacuum switch.  Any idea where I can find one?

[ShelbyDogg]

So, I'm thinking I'd like to replace the vacuum switch.  Any idea where I can find one?

Here are 3 I found by putting the part number in google. 2820487  or 3431020
 RockAuto.com also has it for $57.79

http://cgi.ebay.com/ebaymotors/NOS-Mopar-5-button-AC-Switch-%2F-Control-Ass'y-'68-up-NOS_W0QQitemZ320492406750QQcmdZViewItemQQimsxZ20100225?IMSfp=TL100225135015r9455

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Board=E&Number=5831552&Searchpage=1&Main=5773074&Words=3431020&topic=&Search=true#Post5831552

http://www.cjmotorparts.com/component/page,shop.product_details/flypage,shop.flypage1/product_id,3493/category_id,6/manufacturer_id,0/option,com_virtuemart/Itemid,1/

Might want to try and open it to clean the contacts bfore spending $60 though. It's up to you.

[mapandjlp]

Here are 3 I found by putting the part number in google. 2820487  or 3431020
 RockAuto.com also has it for $57.79

http://cgi.ebay.com/ebaymotors/NOS-Mopar-5-button-AC-Switch-%2F-Control-Ass'y-'68-up-NOS_W0QQitemZ320492406750QQcmdZViewItemQQimsxZ20100225?IMSfp=TL100225135015r9455

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Board=E&Number=5831552&Searchpage=1&Main=5773074&Words=3431020&topic=&Search=true#Post5831552


http://www.cjmotorparts.com/component/page,shop.product_details/flypage,shop.flypage1/product_id,3493/category_id,6/manufacturer_id,0/option,com_virtuemart/Itemid,1/

Might want to try and open it to clean the contacts bfore spending $60 though. It's up to you.

Thanks.  I did the same thing only on Yahoo (searched on the part number) and got nothing....interesting.

I've got it apart and will try to refurbish it first.  I'm still not sure it's the switch.  Maybe I just don't have a good understanding of the wiring but it just doesn't seem to make sense to me.  You know, if I disconnect everything except for the green and blue wires (the ACC 12v in and the 12v to the compressor), the fan will come on when A/C is selected.  Does that make any sense at all???

[FY1Cuda]

I was having similar problems with the blower motor not going on.  ShelbyDogg and Slotts were good enough to give me some advise on the issue.  I traced my problem to the spade connections on  the back of the vacuum switch.  The spades were loose on the copper rivets on two of the three plug wires. When I used an ohmmeter to check continuity between the spade on the outside and the button contact on the inside, there was no connection on one and intermittent on another.  When I tightened up the rivets, the continuity checked out like Slotts has shown in this thread.  I was ready to get that Ebay switch because the auto parts places were saying around $58, but I'm still using the old one.  Good luck.

[ShelbyDogg]

Most of my vacuum nipples were broken off on my switch. I found a new 5 button control at a swap meet for $1 that didn't turn the fan on and flip the doors for the e-body settings, so I cut it open and put my old switch's sliders into it. Now it works as it should.    Don't pass this stuff up at swap meets. Everything is good for parts.

[mapandjlp]

Most of my vacuum nipples were broken off on my switch. I found a new 5 button control at a swap meet for $1 that didn't turn the fan on and flip the doors for the e-body settings, so I cut it open and put my old switch's sliders into it. Now it works as it should.    Don't pass this stuff up at swap meets. Everything is good for parts.

How did you seal it back together?

[FY1Cuda]

I put super glue on the little "pegs" and then at each end of the switch I did a loop of thin steel wire and twisted it tight to snug it up.  I had to open it back up and was glad to find that the super glue wasn't all that super.  The wires don't look good but work nicely.

[ShelbyDogg]

I cut it open with a razor blade, cutting off the raised plastic "rivets", to put it back together, I took a small drill bit, then put in (7) #4 x 1/2" oval head screws in it. The tape on the drill bit showed me how deep to drill. I didn't like the wire idead because the switch control has to sit flat against the panel. If you get it open, the contacts can be cleaned by scraping the heads and the contact plate with the edge of a razor blade or x-acto knife.

[FY1Cuda]

Thanks again, ShelbyDogg (Rob), for all your expertise on this subject.  I'm afraid you shamed me into pulling my switch, drilling and screwing it together.  It's definitely a nice fix, and besides, I'm pretty darn familiar with the innards of the switch by now.

[ShelbyDogg]

FY1Cuda,  Screwed together just looks better. No thanks needed, now you'll be able to help other users with this.

Thanks.  I did the same thing only on Yahoo (searched on the part number) and got nothing....interesting.

You know, if I disconnect everything except for the green and blue wires (the ACC 12v in and the 12v to the compressor), the fan will come on when A/C is selected.  Does that make any sense at all???

mapandjlp,
I think that I figured yours out after reading this again.
You have your green and blue wires switched in the bulkhead connector. You are getting power through the ACC/ plug that should be enegizing the comp. clutch. Instead, it is running your blower motor. That's why I asked if you only had high. It really pinpointed it when you said that it only ran in A/C and still ran with the 3 prong connector off.

[mapandjlp]

You have your green and blue wires switched in the bulkhead connector. You are getting power through the ACC/ plug that should be enegizing the comp. clutch. Instead, it is running your blower motor. That's why I asked if you only had high. It really pinpointed it when you said that it only ran in A/C and still ran with the 3 prong connector off.

I thought the same thing so I reversed them (one of the first things I did) and it made no difference.  I've been looking at the harness under the dash and none of it looks really great.  Perhaps I need to consider some new wiring if this switch rebuild doesn't help...

[ShelbyDogg]

I thought the same thing so I reversed them (one of the first things I did) and it made no difference.

You notice that I said BULKHEAD Connector and not the 2 wires that plug into the vacuum\fan control switch, right?  There is no way that the fan will still run if you changed the 2 wires at the firewall.