Ran my car today and the heat was on. Seemingly whatever I did (ac, outside air, etc) it felt like the heat was on max and I could only change the fan speed. I've got another set of controls from my parents house coming to test but has anyone else had this issue? If it's on the electronic controls is there another known fault?

 

Hey bud, have you checked to make sure that the mix door is functioning? The FSM walks you through the process of testing all these things and figuring out if its a motor problem or a circuit problem.

I had a similar problem this last year, so here's how I solved it. I followed the FSM and checked all the functions of the controller. The functions that weren't working, I traced with a multimeter until I found a broken solder joint and repaired it. Might not be your problem, but if you have been tugging on the back of the controller, either to install it, or put in a radio or something, I'd give that a look.

Check the FSM first

 

I hadn't touched anything in or around that area since I got the car. I know there is a temperature control actuator, is that what you are referring to? Not sure what the mix door is. Dreading having to pull the dash!!!!

 

So you've got 2 things that work together to control your heater. The first thing is the control unit in your dash, the second is the mechanism that does the actual work. When you pick a temperature, the control unit sends power to a little servo motor that moves a flapper door. This flapper door regulates where the air to your vents comes from. Sometimes that gets stuck for various reasons and all you have is air coming from your heater block full of radiator fluid.

If you plan on fixing this type of thing yourself, print out the pdf manual here and go through it step by step. If you've exhausted those possibilities and the darn thing still doesn't work, you're gonna have to start checking your connections one by one with a multimeter.

Link to manual: RotaryHeads.com - 2nd Gen RX-7 PDF Technical Manuals FC3S

 

My flapper wasn't working since I bought the car, I've got a wire that I use to pull the door open or closed to turn the heat on and off, haha.