grady95

My project car is an 84 GSL-SE. The short history of it is that it sat for ten years in a barn and I am now the new owner and trying to get it roadworthy. It is now running and on the road as a rolling restoration. The previous owner bought the car at a police impound auction ten years ago. It had been stolen and recovered. The theives did some minor damage, the usual stuff; broke the ignition cylinder, stole the radio. I have to find a way to fix the defroster. They pulled the radio out pretty cleanly, actually without cutting any of the wiring harness. I can see right into the underdash area.
The heater controls are the standard type push buttons reading:Heat, Bi-Level etc. The blower motor works and the heat is coming through but I can't seem to find a setting that directs the flow up to the windshield to defrost it. This is a problem here in balmy Rochester, NY!
Is there an electric motor servo that actuates a damper for this with a fuse maybe? Some foreign companies use variable resistors in the climate controls. I know Nissan does anyway. If not electrical, is there a "stuck" door I can get to and free up?

mazdaverx713b

iTrader: (91)

the variable resistors are commonly used for fan speed. the problem could be bad solder joints in your logicon. does the indicator light light up when you press the defrost button?

grady95

No it does not light up. The push buttons seem to have no real effect on the direction of airflow. They do feel like they are depressing mechanically with a positive click felt by my finger, but the air blows out from the dash vents only. I'm a little challanged with some of the wording...What's a "logicon?" If I can find it, I can fix it!

Yes, my son's Nissan does use the resistor to control fan speed. Good point.

mbonner

No mouse nest in there for being in the barn all that time? I ask as it has happened to me twice now.
Mike

Rx-7Doctor

iTrader: (13)

The logicon is the unit that is attached to all of those function buttons. It's a electronic control system. Are any of the functions working such as heat or air?

Manntis

+1. Check for physical blockages in the ducts before you start chasing wiring gremlins.

grady95

Actually yes. Mice or something nested in the airbox filter. When I first opened it, there were no living cling-ons but there was a nice fluffy nest built out of dragged in materials and fluffed up filter cardboard. They seemed to have crawled in from the intake.

grady95

I'm back in Rochester tomorrow night late. I will check this and report back to you Tuesday to be sure, but I believe that there are pushbutton controls which just don't change the airflow when pushed. The air is heated, so the thermostat is opening and the fan is blowing. Obstruction may be the key. I may need to disassemble the box and just look around. I'll get back to you on this. Thanks for now.

grady95

Seems reasonable. I wil be back up north in a few days so I'll look at this and get back to you. Thanks for your help.

Rx-7Doctor

iTrader: (13)

When you push one of the buttons to change the mode you should be able to hear a mechanical reaction. Meaning that you hear it changing the flap doors to the appropriate function.

3rd and final 7

iTrader: (9)

mine was doing the same thing, i fliped the switch for the rear defroster and it worked!

grady95

I am home, it's REALLY cold, and it would be nice to diagnose and solve this defrost issue! I have gone out to check on your point about there being an audible report from the dampers moving. On pushing in any of the control buttons on top of the logicon, there is NO audible report. There is no apparent change in air flow either. There appear to be small indicator lights mounted in the buttons. If that is correct, you need to know that there is no visible evidence that the lights present either. In fact, other than simply feeling the buttons click as they are depressed, I have no control with the buttons at all. There are two rotary dials below controlling air temperature and fan speed. Both of these dials do perform their assigned functions well. Access is a little difficult for direct visual examination, so it would be useful to have some idea what to target before just breaking into the system on a fact finding mission. Suggestions welcome!

Rx-7Doctor

iTrader: (13)

Everything is pointing to the logicon being bad. When you depress a button that corresponding light should show. Too bad the systems are not designed like German cars. Meaning that when the system goes out it defaults to defrost mode. Being that it is a built in safety feature so you can keep the windshield clear. But the German A/C, heater system is way more complicated.

bliffle

I have similar problems with my SE, but since the airflow is OK and the A/C worked good I ignored it. But now with cold weather I've gotta fix it. But where to start!? Do we have to pullout the logicon and then go spelunking for a good one at the JY? Are some parts fixable?

Hmmmm. Is it all worth it? Oldtimers used to get a small fan that ran off the cigarette lighter that suctioncupped onto the winshield and blew air across it to defrost it. Hokey, but effective. In a pinch.

r0gu3

I had that issue where the lights for the settings wouldn't come on and it ended up being the fuse for it.

grady95

Interesting? What car do you have? I have tried hard to test and retest the fuses to eliminate that from the realm of possibility, but I will track down any lead. Was the fuse a blade type or an in-line?

grady95

Doc,
Boy, did you hit a sweet spot with this one. I have worked on Porsches for years! I currently own and drive a 2000 911/996 Carrera Cabriolet. They are my vehicle of choice. The two main reasons for getting involved with the RX7 were:
1) Get the Porsche off the road during the inclement weather months here and
2) Being a Cabriolet, I can't pass the broomstick test at the track in this car so I need something else for doing DE this season at the Glen. The Mazda will suit this well because really it is not an overpowered vehicle like the Porsches are. I will be working on learning to carry speed into the turns rather that just shoving it through with the right foot. Besides, being a closed cockpit means the broomstick does not apply.

You are correct about the beauty and complexity of German engineering, but there are some very nice points to the Japanese cars as well. They do differ in ways which make obvious the difference in price, but for the money, these Mazdas make efficient use of simple tried and true engineering concepts.

I am getting a little off topic here, sorry. It is starting to look like the Logicon has bought the farm here. I am going to start a search for a replacement. I'll keep you posted. Thanks for the help.

jl_rotary

now what is the easiest way to remove the logicon on? is there a write up on this? really wondering how to remove that "one" pita clip....