Well, when I bought the car I knew that the hot/cold mixture was not working properly. The previous owner took it to mazda and they said it needs a new Logicon. He didnt want to pay the $$ so he rigged the heater lever to manual so he could get heat.

I dont want to fool with a stupid lever, I want to fix the damn logicon!

I pulled it all outa the dash. Horible cold joints everywhere, need to resolder obviously, but there are a few burnt components on the main circuit board. Resistors R11 and R16 look BURNT. Also, Diode D14 looks burnt cause its between the 2 resistors. There seem to be no other burnt components, I do not have a Transistor checker so Im not sure what to do besides replace the 3 burnt things. Take a look at the pic I attached, its nasty looking but you will get an idea. Hopefully I can get the right parts, its hard to see it.

How can I check the mixture control motor? Ive heard that they may sieze, what do I do? put 12V+ to it??? What about these other transistors??? Nothing smells. Anybody know which transistor controls the airmix motor?????

 

I have tried to fix these logicons several times with no sucess. Even by resoldering everything I still had no sucess. I did find that most of the junkyard around my area these component were not too hard to find. It may be just easier to go buy a used one from a junkyard, I bought 3 for like $10. As for the mixture motor im not sure how you can check it.

 

http://www.mazdatrix.com/o86elect.htm

 

http://www.iluvmyrx7.com/Technical_I...ice_manual.htm section 15 of the manual. About page 93 or there abouts. Junque yard Logicon is the way to go. Then again it could be a fun adventure to fix it.

 

Well I dont really know what to do... None of the junk yards in my area have a 2nd gen, let alone a logicon.

I hate to buy a logicon (used) for 20 bux if I can fix the one I have for a few cents (I have resistors and transistors at my house). I also hate to buy a used, working logicon and have IT smoke because of a bad mix motor.

Someone has to know what wires the motor is on. I have the service manual for my car, unfortunately I cannot look now, im at school.

Does anyone else have anything to say about this stuff?

 

1. Check the resistance of the air mix motor:
a. Disconnect the connector from tLogicon switch.
b. Using an ohmmeter, measure the resistance between (f) terminal and (g) terminal.
c. Result: 17-21 ohms
2. Checking operation of Air Mix Motor:
a. Disconnect the connector from Logicon switch.
b. Connect the battery positive terminal to (f) terminal and battery negative terminal to (g) terminal.
c. Confirm that the motor stops at MAX-HOT position.
d. Connect the battery positive terminal to (g) terminal and battery negative terminal to (f) terminal.
e. Confirm that the motor stops at MAX-COLD position.
3. The (f) wire is YELLOW and the (g) wire is GREEN AND WHITE.
4. Curious: whats the deal. You can log on to this site and write but there is something that prevents you from downloading the schematics and the rest of the manual from the site on-line????? What is it? A shared computer or Library computer? STRANGE.

 

I just dismanteled a Logicon that was sitting on my trash heap and it has the exact same burn area that your picture has. I can't remember just what was wrong with it that caused it to be on the trash heap. Its been probably a year to two years ago that it got chuncked. Just general info.

 

That is really strange how both our logicons fried in the same area, yet it means that it is common. Maybe someone has a fix for this problem?

Anyways, after carefull close examination under a microscope, I found that the blue reister actually seperated from the solder undernieth, it actually was not making any contact. Along with 2 other componets which had seperated, I found 2-3 dozen cold solder joints. OH GOODY! I was actually kinda happy. I also tested most of the transistors with my multimeter (dad showed me how) and they are all good. Even the resisters were still good, but I replaced them anyways. The diode was fine.

So Wednesday I will try out your little test on the motor. Thank you so much. This problem is becoming a swift task, just hope the logicon works!

 

BTW, Hailers,

You said you had a fried logicon but dont remember the deal with it... well do you remember if your mix motor was shot? Did you just replace the logicon and have a nice day?

 

No. I just replaced the Logicon. I did the test of the air mix motor and it worked when I put power to it. I've had several different problems with the Logicon such as the air conditioner button not being functional, just about any of the other buttons not working. Its your basic piece of junk like the wiper motor switch(wiper motor itself does seem reliable). I finally bought one that worked in the junque yard and have had no problems since. Just saw a post today where a fellow said he never heard about rx's having heating problems. Sheltered life he does lead.