If a 2 wire switch has been installed in place of a one wire switch then one wire would have to go to ground in order for a 2 wire switch to work correctly
A/C Electrical Problem
I have an 84 and the cooling fan quit working. I have replaced the relay and plug, have checked fan motor direct from battery and it works. I am ready to replace temp switch. I came across the wiring diagram that shows the a/c pressure switch also controls the fan when the a/c is on. There is a high pressure switch at the compressor and a cooling fan switch connector on the compressor. Someone has had their hands on this before because the fan switch at the compressor has two wires not one. Can someone guide me as to how all this works together. I tried turning on the a/c and the fan didnot come on.
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Regardless of what has been done if you ground the wire TO the fan switch or the A/c pressure switch then the fan should runhave checked fan motor direct from battery and it works. I am ready to replace temp switch. I came across the wiring diagram that shows the a/c pressure switch also controls the fan when the a/c is on. There is a high pressure switch at the compressor and a cooling fan switch connector on the compressor. .
If it doesn't then you have other problems ( wiring ? )
Thank You for your reply. One wire was connected and the other was taped off. Does it matter which wire is grounded? Also, which pressure switch is tied into the fan circiut. From what I can tell the verbage for the one at the compressor is called high pressure switch and the one near the evaporator is called the pressure cycling switch. The schematic only refers to a/c pressure switch. Can you help me with that?
It's a ground switch so no, it doesn't matter which one. And I'm pretty sure it's the low pressure switch at the tank....
I just made that ground connection and the fan comes on at the turn of the key. I think I still have a wiring problem based on the information I have read. The fan is to come on when the A/C comes on and/or when the temp requires it. The fan now comes on when key in run position. Any ideas?
Starting to sound like your wiring may have been altered (like mine) to get the AC to kick in. Mine either has a fault in the electronic ac/heat control or in the ECU. So someone added a a ground connection to the compressor relay, which on my 93 is located on RH/pass side near the Freon tank. This also of course turns the rad fan on. A quick fix would be to first find the added ground wire and add a switch.
All of this may not apply at all to a 84 though. I have no idea. But a quick check would be 1. does your ac work? (i.e. compressor clutch kicking in). and 2. If so, dose it kick in when you have all the ac/heat turned off? If so, I'd look for a added ground to the compressor relay.
All that being said, it doesn't hurt anything. I kept the fan running all the time on my 84 TA....
All of this may not apply at all to a 84 though. I have no idea. But a quick check would be 1. does your ac work? (i.e. compressor clutch kicking in). and 2. If so, dose it kick in when you have all the ac/heat turned off? If so, I'd look for a added ground to the compressor relay.
All that being said, it doesn't hurt anything. I kept the fan running all the time on my 84 TA....
oh, fyi, a lot of people don't realize that the ECU has control (can turn off) the ac compressor so that it can turn it off at WOT (wide open throttle)...
A/C works and cycles fine. With the a/c on or off the fan is now running full time. I have disconnected both pressure switches thinking that they might be stuck in grounded position with no affect on fan. I have read that the 84 vette ECU does not control fan. I will research further. I was concerned that the fan running all the time might over load wiring and melt or cause a short. What you think?
Never did on the TA, and before I added a cut off, mine ran all the time also....
So it would appear you have a different type of switch that has both wires going to ground ( allows you to control 2 circuits with one switch ) so grounding the 2nd wire has given a permanent ground connection on the fan circuitI just made that ground connection and the fan comes on at the turn of the key.. The fan now comes on when key in run position.
Any ideas?
Disconnect the 2nd wire
:iagree:I have read that the 84 vette ECU does not control fan.?
As per the circuit diagram above ; '84 fan control is independent from the ECM and purely by mechanical means; switches to ground operating the fan relay
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