So two months ago when I bought my '86 RX-7, I was told that the only thing that didn't work on it was the blower motor. Today I attempted to find the problem in order to get the damn thing running using the heating FSM for the S5. The first things I tested were the heater and ex-hi relays (going a bit out of order). Both worked just fine. Then I checked the fuse and breaker. Again both were fine. Then I tested the terminal wires of the blower motor connector by touching the positive lead to one of them and the negative lead to the metal joint in the door. Both showed no voltage. I then went after the heater relay connector and tested each connector in the same fashion as the blower motor connector. Again, it showed no voltage. Being the curious person that I was, I began to connect terminal wires to eachother on the heater relay connector. When I connected the red/yellow wire to the blue wire, the relay clicked and the blower blew on at full power! This startled me as I was under the blower when it magically clicked on. When I went to set the speed from max to medium, the relay clicked off and the blower stopped. Thinking it was a problem with the power transistor, I turned off the car and went back to my room the get my tools in order to remove the blower. When I came back, I wanted to see if I could replicate the blower turning on again. I turned on the car, started to slide the blower switch to max when all of a sudden, the switch worked! The blower began to move faster as I moved the switch right until it got all the way to the right and the relay kicked on.

My questions are, how could shorting the heater relay "b" and "e" connections temporarily allow the relay to snap on, the power transistor or the relay not work again until the car has been restarted, and the blower motor/logicon work perfectly afterwards?

 

I've no idea. On the Heater relay and the Ex Hi relay are a green/black wire. That wire should be hot anytime the key is ON. That green/black wire on a series four is to power the coil of those relays.

The green/black wire(s) are in turn powered by the IGN relay on the blower housing. The Ign relay pulls in if it has power from the Meter fuse and its coil has a ground from the starter solenoids coil.

So the power for the relays coils comes from the Meter fuse ....thru the Ign relay.....to the coil on the Ex Hi relay and the Heater relay.........and also leaves the heater harness as a green/black wire and feeds power to items in the Logicon.

The Blue wire you jumpered to is from the HEATER fuse/breaker.

If the Ign relay on the box does not pull in, then you lose power to the two relays and the logicon. So no power on the green/black wires on the relays also means the logicon is disabled also. Or part of it anyway.

A 86-87 wiring diagram should look like the one attached. I colored the power from the Ig relay to the other relays and logicon in Red.

The power for the coils is from the Meter fuse thru the Ig relay and the ground for the Ex Hi and Heater relays is from the Logicon. So you can see, if the Logicon does not get power from the green/black wire, the relays will never ever see a gnd signal put on the Heater or Ex Hi relays. Blower won't hardly work like that.

I also can see how someone could lose his blower motor action if he messes up his starter circuit wiring i.e. no gnd on the Ig relay.

 

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hi guys, gals..

something to check..

the 8 pin plug that connects the harness to the fan motor circuit

the plug is mounted on the fan assembly..

it can get hot and the pins spread breaking electrical contact..

if its bad enough it will melt the plug and cause further issues..

thread on ausrotary about this issue -

http://www.ausrotary.com/viewtopic.p...3054&hilit=fan