84 Cooling Fan Sensors

[Bill B.]

Nearly complete in returning my 84 to original shape but COOLING FAN (no auxillary) wiring is driving me CRAZY. Seems the 84 harness is a "single" year arrangement for sensor inputs/connections. If I have it right, only two sensors control fan "on/off" conditons: the eng coolant temp switch (1-wire connector) and the A/C Pressure Switch (1-wire connector). Doesn't appear that the ECM provides any input like the 85's and up.

So, my question is where is the A/C Pressure Switch--is it the two clip sensor on the back of the A/C compressor?

[Joe L.]

Re: 84 Cooling Fan Sensors

Bill-----

For both 1984 and 1985 the temperature and pressure switches are located in the evaporator inlet line. Both switches are still available from GM. The pressure switch is GM #10007057 and GM lists for $39.30. The temperature switch is GM #14078970 and GM lists for $30.25.

[Bill B.]

Re: 84 Cooling Fan Sensors

Joe, I am really mixed-up now. I have a simplified wiring diagram which I got from a CrossFire website a year or two ago. It shows engine compartment side Connector 100 @ Pin 2F to consist of two single wires: one "tan" to AC Press Switch and the other "brown" to Eng Coolant Temp Switch. I thought the engine coolant temp switch for 1984 was located on the front left-hand cylinder head? For 1985 I think the harness arrangement is the same but the switch was moved to right-hand head? Anyway, my problem is that a previous owner bypassed the original setup and direct wired the fan! In the process he pulled wires with their connector internal clips from the connector housing on the interior side and clipped off the sensor connections on the engine side.

Now, I have the above "tan and brown" wires without connectors hanging in the harness. They also trace back to pin 2F. If I attach a connector to the "brown" wire--it works with my left-hand cylinder head sensor location. That leaves me with a "tan" wire which I simply don't understand where/how it is suppose to be connected. FYI, I do have two intact connectors on the AC system: one two prong on back of my AC compressor and one two prong that attaches to sensor on evaporator inlet line.

My fear at this point is that the "AC Prss Switch" is the sensor on the back of my compressor which already has a perfect fit connector and traces back to Connector #100 per wiring diagrams. Kinda feel like I am in a controlled tail spin.