Hi, first post here. 87 RX7 from girlfriend has heater not working.
It appears that air is still coming from front vents regardless of setting (defroster, legs, head, etc). Only cold air coming out regardless of temperature seting position. Have Haynes manual, but it doesn't include heather wiring diagram. Two questions, where do I find wiring diagram? And second, problem was sudden, not like heater core plugging. Expecting valve and other electrical component not functioning properly, any suggestions?

Thanks in advance, Abel

Would you please copy muycapaz@aol.com on your response, thanks.

 

This is actually the first time I have heard of anyone with a heater problem. Have you checked the heater hoses?

 

The heat-A/C control is called the logicon. Look up "cold solder joints".

 

Ryde_or_die, thats so mean. We were all nubies at one point.



Hey Newbie, check out my post about MY fried logicon! Its not to far down the list.


You can download the factory service manual from some web sites, do a search on here, Iforgot exactly where, they are HUGE though, like 1000 pages.


There are LOTS of electronic problems with RX7s. The first thing someone told me when I asked them about rx7s is, make sure you know how to solder circuit boards! there are cold solder joints EVERYWHERE.

 

Are any other functions not working, like wipers or sunroof? On my car (88 SE) the same problem you have happened, but the wipers and sunroof wouldn't work either. Turned out to be the ignition switch. If I turned it back toward "off" just a tiny bit as it was running, I'd hear a realy click on and then everything would work properly. Give that a try. Also try the heater/fan controls with the key turned to the last position before "start." If they work at that position, chances are good that it's the ignition switch.

 

NOPISTONS asks:
<<Are any other functions not working, like wipers or sunroof? >>

Well, horn is not working (horn switch is OK and horns work, I was going to bypass the CPU and install a simple horn relay) also the wipers only work after playing with the ignition key for a while... However other features also controlled by the ignition key do work. Likely the ignition key has more than one "run" position connection, feeding different circuits.....some work, some don't

<<Also try the heater/fan controls with the key turned to the last position before "start." If they work at that position, chances are good that it's the ignition switch.>>

Good idea !!! Will try that and let you know, thanks for the help.
Have also downloaded the wiring diagram for the logicon, learning fast...
Thanks again..... Abel

 

Go to http://www.iluvmyrx7.com/Technical_I...ice_manual.htm You want to only download the wiring diagrams and the other section thats called something like Body Electrical part one.. Most likely the Logicon has gone south. If you can't down load the parts of the manual, let me know and I'll write back what wires to jumper. I'd just try to download to disk those two sections. If you jumper the motors and the motors work, then its either buy another Logicon or depending on your skills, you might repair the Logicon. I emphasize the words ....YOUR SKILLS, not mine. I can barely plug in the toaster.

 

MUYCAPAZ....Sorry, I see you already downloaded the schematics. Here is SaabGuys post https://www.rx7club.com/vforums/show...threadid=37922 we noticed that we both have a burnt area in the same place, around R16, R1, D14, and R11. If you get a chance to remove your board, will you see if you have the same overheated area and maybe write back, please?/? I've tried re-soldering these things to no avail in the past. I've had great success re-soldering the idiot light panel to get the clock to work, and re-solder the cpu to get the horn to work, but the Logicon, nope. The logicons for 86-91 are the same so it should'nt matter if you look at a 88 manual. SAABGUY...did resoldering fix your logicon????
Abel if you fix yours, please let me know what area of the logicon was defective. Also if you have the above mentioned burnt area would you please let me know?

 

MUYCAPZ.... I did'nt have a thing to do this morn so I thought I'd investigate the Logicon on my car. After fifteen minutes I see why I lost interest in the logicon. Its that plug that goes to the firewall. Thats the one that you'd want to jumper to see if the Mode Control or Air Mix motor work. Trouble is there is no access to the plug at either end. I remember a couple of years ago I cut the wires near the logicon and inserted a male and female Molex connector from Radio Shack, so I could jumper the wires to see if the two motors were ar fault. They were not. So I'm looking today at this harness and saying *it works, don't mess with it*. I think you could cut back that heat shrink and get some wire taps and tap into the appropriate wire to test the motors. Of interest I checked the 13pin plug and have 12v on the white and green wire, the light green and black wire and the blue and black wire. Key on. And a good ground on the black wire.

 

HAILERS, thanks for your help. The car has been running for two yeras sans heater, very seldom needed in San Diego. My girlfriend was told then that "repair was going to be expensive" and decided not to fix it. (We just met a few months ago...) A few days ago she mentioned the heater problem to me and I started thinking about an electric problem since the car has had some electrical gremlims, ie the windshield wipers, horn, etc, didn't work anymore. Have fixed the wipers and have a horn relay to bypass the cpu, but I have not installed it yet.

Now I know about the propensity for cold solder joints and logicon adding a few BTU's by burning components.... however, the car has more than 268K miles and we don't want to spend time or money fixing it. Giving the difficulties about getting to the connectors and the fact that the heater is not that needed in SD, I may postpone the fixing for later.....

Will keep you posted if I decide to donate some blood by scratching my fingers in search of connectors....
In the meantime, thanks for your assistance
Abel

 

ya ya, just keep rubing it in you bastard

 

I came across this today in case you ever don't have anything better to do or it get too cold for you http://home.rmci.net/panther/rx7logic.htm