How many wires are suppose to be on the coolant fan switch on the passanger side of the engine block? Mine has two with a ground to the body and the fan never shuts off. This car came from florida. Any ideas whats going on here?

 

I don't know what switch (device) you are referring to. The only item that comes to mind, in the block, on the right side, is the knock sensor, but it only has a single wire to It. The fan switch is in the head, not the block, on the passenger side of the engine. It is between the #6 and #8 spark plugs. It has a single brown wire connected to it. It sounds as though someone may have messed with your wiring. You will probably have to pull out your FSM and reference the schematic to get it straightened out.

RACE ON!!!

 

Please bear with me Im new at this. According to my FSM on page 6D7the diagram shows the location of the COOLANT FAN SWITCH CONN. Right below the oil dip stick on the passanger side. I changed the coolant temp sensor on top of the manifold. However the electric fan NEVER shuts off. I also changed the cooling fan relay located near the battery.My understanding is that when the temp get to 235 the switch turns on the cooling fan??? Are some 84s built differently? What am I missing here?

 

my 84 on the right side has one red wire for the cooling fan temp switch, yes they come on at 235, do you have your heater or air conditioning on ? I've been looking at upgrading mine on corvette south they have a setup that has two wires so someone could have changed the wiring.

 

heater and AC are off. Mine has two and a third seems to be a ground to the body.

 

Does the A/C have a freon charge?
I think if they loose pressure the fan comes on.
Try disconnecting the wire from the switch, it should turn fan off also see what happens if you disconnect that ground.
Keep an eye on your guage while testing.

 

That illustration shows the fan switch connector just to the right of where the artist has stopped drawing the dipstick tube. Partially hidden by the arrow to the connector is the fan switch, in the head. Further to the right, in that drawing, notice how much lower the #4 spark plug is. The plugs install in the heads. If you have two wires connected to that device, in the head, or if it has a red wire, the wiring has been screwed with. If what you are looking at in your car, is really in the block, as you've observed, I can't imagine what you are looking at.

RACE ON!!!

 

page 8A149 says on the 1984 that the SWITCH should be in the block. Mine is right below the spark plug and the exhaust manifold. However mine has two wires and the those wires plug into the sensor which has two places for the wires comming out which apperas to be factory installed. However a red wire seems to have been spliced into those wires and the red wire goes to a ground on a bolt near the hood latch, however that red wire is not connected but cut and taped. My question now is can the SWITCH be stock in the closed or open position and cause the fan to run all the time??Does this type of switch get stuck often? I have already changed the relay and fan sensor on top of the manifold.

 

There is a coolant temp sensor on the right hand side of the 84 block. It is between the rear cylinder and the one in front of it. I think that one is the fan switch. It has 2 wires now because if you go to PepBoys or Autozone that is the new style, and you can no longer purchase the original single-wire version from them. The old single-wire unit grounded through the threads. The new one comes with an extra pigtail of wire you run to the nearest available ground. I have that on my car and it has performed just fine.

The knock sensor, on my car atleast, is on the driver's side of the block. Also on the driver's side is another temp sensor for the dash gauge of the coolant temp (on the head). Lower on the driver's side is a temp sensor for the oil temp (just above the oil filter), and on the front of the manifold is a third coolant temp sensor, I think that one goes to the ECM to control cold starts and OD if you have the 4+3.

Now, for your problem. Does the fan come on immediately when the car is started cold, or does the car warm up for a while and then the fan comes on? It is very likely that someone installed a colder fan switch, perhaps a 180 degree switch, and that your car never cools down enough to turn the fans off. If the fan does not come on until the car warms up, your switch is likely too cold. If the fan running constantly bothers you, head over to PepBoys and purchase a new stock temp switch and replace it. If the fan comes on immediately when the car is started, even when the car is quite cold, I would suspect that either the switch or the wiring is bad.

 

My FSM doesn't have a section 8A, therefore no page 8A149. However all the 1986 - 1989 C4's with the B4P auxiliary fan and ALL 1984 - '85s have a fan switch in the HEAD. Which head, left or right, depends in the year of the car. In 1984 and 1985, it is the right head.



If you are dealing with a device that is in the block, has two wires, and one of them is red, you are not dealing with the fan switch.



The switch can't be the stock FAN switch, because the stock fan switch only has a connection for ONE wire and it screws into the head.



There is no "fan sensor on top of the manifold". I wonder what it might have been that you changed on top of the manifold, and what the relay really was?

Until you properly locate and identify components, you are going to have difficulty trouble shooting your fan problem. Good luck.

RACE ON!!!

 

He is mistaken about it being in the block. It is in the head. It is the fan switch, but it is the newer one cross-referenced from PepBoys. The newer one has 2 wires, and one of them just gets run to any available ground.


There is a coolant temp sensor in the manifold at the front, behind the air pump. This sensor sends data to the ECM for cold starts and OD use in a 4+3. CFI is correct in saying that there is no "fan switch" on top of the manifold, but the coolant temp sensor there looks exactly like the fan switch one does.

Bottom line, your fan switch on the passenger side has been screwed with. I would bet that the person who previously owned the car installed a fan switch that is too cold (comes on at too low a temp). Best bet is to go to your local parts store and get a new, stock temp switch with 2 wires (the newer one) and install it in the passenger side head. Good luck, and post results.

 

I have a mechanic I know comming to the house to take a look on wednesday. He thinks the person who own the vet may have put the two wires together that go to the switch and that that is causing the fan to ground it self out which turns it on(simular to what the switch does) im probly saying it wrong but I will let you all know if he gets it working whats was actually going on. Thanks for all your guys help and any suggestions for the mechanic are welcome.

 

What happened to "However mine has two wires and the those wires plug into the sensor which has two places for the wires comming out which apperas to be factory installed.???

To see the stock fan switch, which is apparently still available (except maybe at Pep Girls) go HERE.

RACE ON!!!

 

Do you have a fan relay attached to the drivers side wheel well? The fan switch in the passenger side cylinder head should only have one wire attached (brown I think). The sensor grounds the relay that runs the motor. The sensor doesn't need to be grounded with a separate wire.

 

also what he might check since hes changed the CTS is there is a senson on the top backside of the AC compresson, i had the same problem of the fan not shutting off, and it turned out that the plastic on this sensor cracked on an accidental bump, and it grounded out that sensor, and the fan ran all the time

 

This is another example of the FSM errors I mention from time to time.

This is the page ps374 referred and it does state "which screws into the Engnie Block". It does, in fact screw into the cylinder head as CFI-EFI states. Here is the picture from the FSM

Difficult to see, but the Cooling Fan Temp Switch is in the head and is clearly much higher than the ESC Detonation Sensor (Knock Sensor) in the block.
These are from the Electrical Troubleshooting Supplement (Section 8A) of the FSM. CFI-EFI, if you don't have this for the '84, I can email it to you in pdf. Shoot me an email.

 

Ill try to send you guys a photo. It is the switch as shown in the diagram and it does have TWO wires going into the connector. And the wires are two different colors.I believe green and black. Its pretty dirty down there because the valve cover has a slight leak.Sadly to change the valve cover gasket I have to take off the intake since this is a Xram set up.It is not in the location of the knock sensor.I wish it was I think it would be eaiser to work on.

 

ps,

This may be a case of where the fan switch was bad and somebody added a ground wire so the fan is always on. The ground is doing the job of the switch.

 

I DO have it as a PDF. I rarely reference it. I use the schematic in the back of the main FSM book. I didn't realize those were the "A" group pages. Thank you for the offer.

The second picture, fig. 8A-10, is the same illustration as ps374 referenced on page 6D-7. The FSM DOES have errors. Besides saying the fan switch is in the block, my book calls for a T-45 Torx bit for the three rear wheel bearing bolts. It is a T-55. Some people think that because I constantly talk about the FSM, that I think it is flawless and that there is no other way to do things. That couldn't be farther from the truth, but one would have to be really familiar with these cars to effectively trouble shoot codes and the electrics, without one. With the circuit descriptions and explanations of the various functions, it is a great way to learn about the car also.




What switch in what diagram? I don't see any switches,anywhere, with two wires. Is this switch with "TWO wires" in the block or the head? If there really is a two wire replacement, as JLeatherman says, does your switch check out as a suitable substitute for the switch I provided the link to?

RACE ON!!!

 

The only switch with two wires is the CTS for the ECM at the front of the block. The coolant temp gauge and the fan switch are both single wire.