Z28_1991_Camaro

A brief history of my car's cooling system:

Originally had a 305 in the car that would run hot on hot days but was fine otherwise.
I put a 350 in and at first it was the same...it would only run hot on hot days.
I can't remember when it started happening as this goes back many years now but eventually the car started running hot all of the time. I took the thermostat out and I was able to drive the car without it running too hot unless it was 90+ degrees outside, in which case it would still run hot. I installed a new 3 row aluminum rad with new fans and that didn't make any difference. I still couldn't drive the car with a thermostat and it would run hot on hot days. Somewhere along the way my passenger side fan stopped working. The connector on the fan switch was broken and it was late on a Sunday night so no stores were still open and I needed my car the next morning so I grounded the wire so the fan was on at all times. The car was like this for a long time, I was able to drive it so it wasn't at the top of my to do list to get to the bottom of the overheating issue. A new water pump was put on last fall and it too made no difference again. So a few weeks ago I was looking into what could be causing my problems and found that my fans although they were working they may not have been moving enough air. I put new fans on and for the first time in 4 or 5 years I saw the temperature gauge on the dash go down(after I turned the A/C on and the second fan started running). I drove the car a few times like it was and it was now running too cold. So I put a thermostat back in and while it idled in my driveway the temp seemed to stay around 200-220 degrees and everything seemed like it was working. Then last Sunday I drove it for the first time with the thermostat back in and it was running hotter then it should have. This concerned me because the outside temp was pretty cool and if it was running hot in those temps I would definitely have problems in the summer. I'm hoping there was a bit of air in the system still and that's why it was running hot. After doing some reading on here I decided to put a 180 degree thermostat in and change the fan switch to a lower temp to try and get the engine to run a bit cooler. So today I installed a new 180 degree thermostat (I also drilled a few holes in it since the car always ran cooler without any resistance in the thermostat housing and it would be harder to have air stuck in the system this way). I also installed a new fan switch and when I ran the car my passenger side fan did not come on at all. The driver side fan came on around 220 degrees then it would turn back off when it cooled down. When I turned the A/C on the driver side fan also came on right away as it should have but the passenger side still stayed off.
So now I'm left wondering if the reason my passenger side fan stopped working years ago was not because of the broken connector on the fan switch.

This is the new fan switch I installed:

http://www.jegs.com/i/SPAL/063/195TS/10002/-1

I also found the same switch on ebay and it says the following in the description:
"The 195-TS turns a fan on at a temperature of 195° and off at 175°. All that is needed is a relay along with this sensor to control your fan so that you don't have to worry about forgetting about a switch being turned on or off. This is a 3/8" npt thread."

Do I need a relay for that fan switch to work?
Everything in terms of the fan wiring is stock on my car. I assume there is a relay already there that would control the fans? All I did was take the wire that I had grounded years ago and hooked it up to the nut on new fan switch.

Is it possible the fan switch is bad or is my problem likely someplace else?
Any suggestions would be greatly appreciated

Reid Fleming

iTrader: (2)

Check out my signature to diagnose a non working fan.

Ozz1967

iTrader: (4)

Swap sides with your fans, turn the AC on. The fan that wasn't working should now turn on.

If it doesn't, it's a bad fan motor.

When you turn the AC on, does the fan that was working turn on? If not, it's in the wiring. Possibly the fusable links since the AC bypasses the relay.

Z28_1991_Camaro

I will try and go through that diagnostics chart tomorrow.
I have very minimal knowledge of the electrical system and those charts are a little confusing to me at times so I'll see if I can get one of my electrician friends to come give me a hand.

Both of the fans work, the other one worked when it was grounded it didn't stop working until today when I hooked it up to the fan switch. I'm thinking it's got something to do with the switch or a relay.
How do I know which relay is for which fan? Is there an easy way to tell? It wont be easy to trace the wires

Z28_1991_Camaro

I bought a test light and was just attempting to troubleshoot but I'm confused already.
Of the three relays there, I'm not sure which two are for the fans and what the other one is for. But looking at the picture of the relays that Reid provided there are five terminals on each relay. However, two of the three relays on my car only have four terminals.
What is the "test" terminal?
The first step says, "ground diagnostic "test" terminal".

Reid Fleming

iTrader: (2)

The "test" terminal is the plug underneath your dashboard. Newer cars use this to scan for codes.

Z28_1991_Camaro

How do I ground the test terminal?
Is it normal that my relays only have four terminals but in the pictures they have five?

Z28_1991_Camaro

I've been attempting to troubleshoot the problem.
I grounded the "test" terminal and my primary fan came on. This was the fan on the drivers side. This is also the same fan that comes with the a/c and when the engine temps reach approx 220-230 degrees.
Wouldn't the fan that comes on with the a/c and the one that comes on second(at a higher temp then the first one) be the secondary fan?
Or am I thinking about this too much?

Ozz1967

iTrader: (4)

I would next swap both fan relays around to see if the drivers side still comes on. This will rule out the Relay. Two of the relays by your firewall should be identical, those are the ones you want.

Z28_1991_Camaro

I swapped the relays and drivers side fan still works

Ozz1967

iTrader: (4)

Ok, so it's not the fan, it's not the relay.

I don't remmeber, have you attempted to ground the switch wire near the switch on the drivers head to see if that turns the passenger fan on? You must do this with the key in "run" but don't start the car.

Z28_1991_Camaro

I had that wire grounded for years so that my fan was always on. I just recently hooked it back up to a new fan switch to try and restore everything to its stock form.

So it turns out everything is working fine. My gauge on my dash is no longer accurate. Last time I checked it maybe 2 years ago the gauge was accurate within a few degrees of what my laser temperature gun said.
I had my friend who is an electrician come over today and we attempted to troubleshoot the problems and things got very confusing very fast. There were a lot of things that didn't make sense when comparing what was happening and what was shown on the diagrams. When going through the steps on those charts that Reid provided there were things happening that weren't supposed to happen and vice versa.
Anyhow, the first fan came on around 195 degrees and turned off around 175 like the new fan swich is supposed to do. The gauge on the dash however was a little above 220 degrees when the fan turned on. I unplugged the relay for the primary fan and that allowed the engine to get hot enough for the secondary fan to turn on. The gauge on the dash was just about in the red zone when this happened. It's still a scary sight to see that needle on the temp gauge get so close to red. Is there anything that can be done to fix it or am I stuck with it the way it is?

I thought when the a/c was on that both fans would be on but I guess I was wrong.

Anyways, thanks for all of your help

Ozz1967

iTrader: (4)

My temp gauge is off as well. My fan is supposed to come on at 195, but my gauge reads around 230 before the fan kicks on.

Both fans ARE supposed to come on with the AC on, the AC switch bypasses everything so you still have a problem with that.

Reid Fleming

iTrader: (2)

The secondary fan (passenger fan) on my car will override the driver side fan. So even though the driver side shouldn't turn on until 223°, since I have a 200/185° fan switch that controls the passenger side, when the temps hit 200°, both fans will turn on.

It's highly unlikely that turning on the A/C in Ontario in November will result in both fans coming on. Primary fan? Yes. Secondary fan? Doubtful. That's because the secondary fan only comes on when the A/C high side pressure is high enough to warrant turning it on. This happens almost instantaneously during the summer months. But not this time of year.

The secondary fan will also turn on at 235°, which is pretty unlikely to occur in Ontario this time of year. The primary fan alone should be able to keep things from getting too hot.

Check out this longer write up I did on fans and how/when/why they work:
https://www.thirdgen.org/forums/cool...ans-arent.html

Z28_1991_Camaro

Does the fan switch on the passenger side of the engine control the driver's side or passenger's side fan?
If I read correctly it controls the passenger side fan.
If that is true then something strange is happening with my vehicle because my driver's side fan comes on at the temp of my fan switch while the passenger side fan stays off.

I only had the a/c on for like 10-20 seconds when I was testing it. If I leave it on long enough will the high side pressure get high enough that my passenger side fan will turn on?

I would like to test it just to ensure everything is working properly.

Reid Fleming

iTrader: (2)

The fan switch between spark plug #6 and #8 on the passenger side controls the passenger side fan.

Running the A/C for long periods of time at this time of year won't result in the high side pressure rising much if at all. The driver side fan sucking air through the condenser and radiator will easily keep the high side pressure from rising. It's just too cold outside.

If you unplug your driver side fan relay and turn on the A/C, the passenger fan should probably turn on within 30 seconds. After that, it will probably cycle on and off every 20 seconds or so.

Z28_1991_Camaro

It appears as though my drivers side fan is being controlled by the fan switch on the passenger side of the engine.
The fan came on around 195 and off around 175 which is what my fan switch is supposed to do.
What are your thoughts on that? Any ideas why that is happening?
Is the sensor at the front of the engine under the throttle body what is supposed to control the drivers side fan?

Reid Fleming

iTrader: (2)

The driver's fan is turned on by the ECM. If you have replaced the chip in your car (or a previous owner has replaced the chip), then there is a good chance that the car was re-programmed to turn the driver side fan on at a lower temp.

The temp sensor at the front of the engine is the Coolant Temperature sensor. This controls what your dashboard says.

Z28_1991_Camaro

I did have a chip made when I swapped my engine. I don't remember if anything was done to change the fan settings, I will look into that.
My passenger fan didn't turn on til around 230 degrees yesterday when I tested it. Any thoughts why that may be?

Z28_1991_Camaro

If I change the temp sensor at the front would that make my temp gauge on my dash accurate again or is there just no hope for that dash gauge to ever b accurate?

Ozz1967

iTrader: (4)

That won't affect the Gauge reading. Mine reads 20-30* hotter than what the gauge should be. There are some shops that recalibrate and repair them but they are getting hard to find.

Veaceonee

iTrader: (1)

No its not. The one for the gauge is in the Driver side head. The CTS at the front of the engine is for the computer.

Reid Fleming

iTrader: (2)

Right you are.