I havent had A/C for about a few years and today I finally removed my A/C rad...everything is removed except for the big tank looking thing up by the passenger firewall. The hardline going from that to the rad, it has a weather pack plug-in, what is that?

I removed the hardline and just left the connection but its not plugged into anthing...will I have problems?

 

hardline

 

thats the high pressure fitting.
leaving it disconnected will be fine, without looking at a wiring diagram im not sure if either wire is hot, i don't think they are, so to be safe just tie it up so it won't get into anything.
or if your sure you won't ever put the A/C back on, you can follow the wires back & cut them & then tape up the loose ends.

 

That is the ac pressure switch.

When you turn on the ac, the primary fan activates. When the ac system hi side pressure gets hi enough, it activates the secondary fan by way of this switch.

I believe it operates by closing the ground to the fan relay, in which case there would be no hot wire in it anyway

 

can I use the wires that are on the connection to some how turn my secondary fan on? I might aswell wire up the second fan to a toggle switch so I can turn it on when I want.

How can I do that?

thanks for the info guys

 

You should be able to. Closing the circuit between the two wires in that connector should activate the secondary fan. Actually, IIRC, it should activate both fans. IIRC the ecm is tied into the secondary fan. It has no control over the fan, it's only an input to let the ecm know the fan is running. If the ecm notices the secondary fan running and the primary (ecm controlled) fan is not already running, it will go ahead and activate it.

It's been a little while since I had a close look at it. If you hook it up, post back and let us know how it works.

 

That would be great if I could get the second fan to come just by hooking the wires up to a toggle switch. The connection only has to wires on it, a blue and a black wire. Since Im not ever planing on using A/C again on the car Im wondering if I just cut the connection off and mount a toggle on the 2 wire will that turn the fan on? that seems to easy!

 

if you want to test it before you chop wires, get a 2 inch long pice of wire, bend it around, and stick the ends in the connector. Then go turn the ignition key on, and if the fan comes on, it works.

There's a wiring diagram in this thread.

 

nope didnt work. I did what you said and the fan didnt come on. I even started the car to see if that had anything to do but still didnt. I knew that was to easy....LOL

 

It should work. I just tried it on my car. I disconnected the plug from the ac line, and with the key on, the passenger side fan engaged when I stuck a paperclip in the plug terminals. Does your second fan ever come on by itself?

 

yeah it used to come on when I had A/C but I pulled everything out about 2 years ago. SO it hasnt turned in 2 years. I know, I know...way late on this mod....let me go out again and check, Im at work right now.



Nope, didnt work I went out there and shoved a paperclip in the connector with the key on and nothing happened. I wonder what it could be? I know the fan worked when I had A/C would removing all the A/C stuff have anything to do with it not work? I left all the connections that used to go on the compressor, their just hanging there but tucked away.

 

All you need to do is ground the green/white wire on your secondary fan relay. Hook up a toggle switch on this wire and you can turn on your fan whenever you want.

On my 89 it was the grn/wht wire, hopefully it's the same on your 87.


EDIT: The thread posted by black89ws6 shows a diagram by breathment

 

where is the secondary fan relay? got a picture?

 

No picture, but both relays should be on the pass side by the radiator/battery area.

Which one is which? Not sure, you might have to disconnect one relay and see which fan works to narrow it down, unless someone has a good picture showing it.

Also I don't have my car anymore otherwise I'd go and take a look myself.

 

it's not a pic, but it should be close enough

 

ok, heres what I found. I traced the wires from the fans back to where the replays should be and found 2. The one with the green/white wire is mounted infront of the battery and right behind the passenger headlights.

So all I need to do is put a toggle switch in between the wire? and then I can turn the fan on at will?

 

I just realized my scan posted above may not be correct. It's from a manual for an 89. For an 87, the auxiliary fan relay may be in a different location.

The wire that activates the primary fan relay when grounded, should be dk grn/white. The wire that activates the secondary fan relay when grounded, should be grey.

Still, closing the circuit at the pressure switch should activate the fan. If it is not doing so, there is an electrical problem somewhere. Try connecting each terminal in the pressure switch plug to a known good ground. Try it in a quiet place, with the key on. If you hear a relay clicking, but no fan, then there's either a problem in the fan power supply circuit, or the fan is bad. If you don't hear a relay clicking when you ground it, then the problem is likely in the wiring to the relay, or the relay is likely bad.

Most of the info I've posted applies directly to 89 models, but it's highly likely to be the same for an 87

 

well I tried looking at the fans and cant figure anything out...wiring is NOT my thing and I have a hard time with it.

I tried doing what you said and checked each terminal on the plug by sticking one end of a piece of wire into the terminal and grounded it on the - of the battery, it was the closest and I heard nothing, yes the switch was on. I did that on both the terminals. I know that the fan worked when I had A/C.....So im lost.

I give up...and cant figure this out. how can I check the fan itself?

do I have to start cutting wires?

thanks for all the help

I want to get this second fan working so bad!, I mean its just sitting there doing nothing.

 

If the fan worked before then you need to see if it's the relay or fan itself.

You can swap the relay with your primary and see if that works.

To check the fans hook them up directly to the battery. I used long wires with alligator clips at the ends...or if you dont have alligator clips handy you can also swap the connectors on both fan motors to see if the problem moves to the other motor.

 

I studied up on willie's dual fan article. It looks like the ac pressure switch does not activate the second fan until 88. I couldn't find a valid link to the article, but I had a copy saved on my computer. PM me your email addy, and I'll send it to you. I'll quote the relevant lines from that article here:
"The secondary fan is controlled mechanically through an in-cylinder head thermal switch only
(1987) and A/C head pressure (1988 – 1992). The thermal switch engages the fan when coolant
temperature reaches 243° (or similar). Also on 1988 – 1992 cars, the fan is turned on with air
conditioning as described above."

It looks like the only thing that activates the secondary fan on an 87 is the fan switch in the passenger side cylinder head. Sorry I sent you running around trying to activate it with the ac pressure switch.

The fan switch should be between cylinders 6 & 8. It will be below the exhaust manifold, and hard to see. If you unplug it, and ground it, with the key on, that should activate the secondary fan. If it works, you can tie a grounding switch into that wire for manual control of the fan. I'm sorry again that I led you in the wrong direction.

 

you mean the connection that is plugged into my Hypertech fan switch? I thought that only controls the primary fan (drivers side) how can that switch contrl both fans? When my A/C was connected and the car I guess reached a certain temp with the A/C running then the passenger fan would kick on.
when my car reaches the set temp of the switch it cuts the primary fan on, which is 165* .......

if I unplug that and mess with it isnt that going to screw up my primary fan function?

your helping me learn and I thankyou for that!

 

It won't hurt to unplug it, unless you forget to plug it back in.

The primary fan should be controlled by the ecm. The fan switch should control the secondary. Also (don't know about 87), but on my 89, anytime my secondary fan comes on, my primary fan comes on about a second later. I know this becasue I installed a 200 degree fan switch for my secondary. Originally, my primary came on around 220, and my secondary came on around 240. Once I installed the 200 degree switch, the secondary comes on at 200, and the primary fan always engages immediately after the secondary fan engages. I'm fairly certain when the ecm sees the secondary fan activated, it goes ahead and activates the primary if it's not already running. So, in a manner of speaking, the secondary fan system can activate the primary fan.

Try unplugging your fan switch and grounding it's wire (key on). That should activate the secondary fan, or make the relay click.

See if the fan wires will reach if you switch the fans around. Then see if the other fan comes on. That will rule out a bad fan.

 

OK.........when you say ground it out, do you mean with the paperclip or something? just run a wire from each termial on the plug to eachother?

 

There should only be one wire to the fan switch. Just connect it to ground. That should activate the fan relay, which should in turn activate the fan

 

Sorry it took me so long to get back to ya but I had to work overtime. Anyways I just back back from under the car and I disconnected to fan switch plug and stuck a wire in there and grounded it to the frame and heard some clicking noises and then soon after that the passenger fan kicked on!......but not the drivers fan...so the drivers fan will not kick on until I have reached the temp settings that are in my ECM and when the motor heats up, correct? So am I just to splice a wire into the fan switch wire and run it to a toggle and run another wire from the toggle to ground?

will everything still work normally but when I flip the toggle switch the passenger fan will kick on?

 

That should do it. Glad you got it figured out.

 

Really? You are the MAN!!!! Black89ws6!!!

Thank you very much for hangin in there with me and looking stuff up and walking me thru it!.....

 

No, you figured it out man. Credit goes to you. I just helped a little. Heck, I was giving you bad info for the first half of this thread because I didn't realize the 87 dual fan systems were a little different.

You might want to figure out why your hypertech fan switch hasn't been engaging the secondary fan, though. Or maybe your engine just never gets that warm (from inside the car, with the hood down, I can never tell the difference between 1 fan or 2 running anyway).

Do me one favor though. On my car, grounding that switch with the key on, activates the passenger side fan. Grounding it with the key on AND the engine running, activates both fans. I'm just curious if that much of it is the same, from 87 to 89. If it is, your new switch will activate both fans for you.

 

alright, Im having a brain fart!.......I cut the wire and spliced one wire on one end and another on the other end, ran both pieces of wire into the interior......now I have a 3 prong switch so its lights when I have it on or off.....Im stuck and dont know what to do with the wires.
The 3 prong has, power, ground, and acc.


HELP!!!!!!

told ya wiring wasnt my thing.!!!!



Should I have just run one of the ends to a ground and then what do I do with the other end?


Im stuck....

 

nevermind,,,,I figured it out. Tie the 2 end together run that to the ACC prong and then run a wire from the ground prong to a ground then run a wire from power prong to power and that gives me light.

whew!!....sorry for jumping the gun....brain fart was big!....

 

I cant get this to work. When I wire it the way I said above the fan does not cut off with the toggle. I have tried different ways of hooking the wires up but it just will not cut off. It stays running. whats up?

 

3 prong switches do weird things sometimes.

A 2 prong switch would be simpler. Tie one side to ground, and the other side ties in to the same wire that goes to the fan switch.

What is the purpose of the 3 prong switch? Are you trying to make it light up with the fan on or something? I can help you hook it up if you tell me what the label on each prong says.

 

I think cutting that fan switch wire freaked out the fan switch and ecm cause my primary fan starts running now when I crank the car up and the gauge doesnt show temp but it did that this morning after screwing around with it lastnight and it went back to normal...we'll see in the morning after car sits all night...I unplug the ecm fuse to reset everything.
anyways, after reading the other post about splicing a wire into the green/white wire on the secondary relay I thought what hell? and gave it a try....and BAM!!! the toggle switch works when wring it up that way. I tested it outside the car first with a spare switch......So I put the fan switch wire back like it was and used one of the wires that I had already ran inside the car. put that wire on 1 prong grounded the other prong and ran the other prong to power,(for light) and it works....I can now cut the secondary fan on when I want.

So since that seemed to work do you think it will be ok wired up like that?

this has been a nightmare!

I just hope my temp gauge and primary fan goes back to normal. any ideas on that?



Also, I was doing this to try and cool down the radiator seeing that I have my trans cooler going thru that.....well, when I cut the secondary fan on the trans temp starts rising.....I guess cause the fan is right infront of the trans cooler and pushing all the hot air in that direction...


hell I dont know!!

 

Are you sure your fans aren't plugged in backwards? The green/white wire should go to the relay for the primary fan. The wire that you ground to activate the secondary fan relay should be a gray wire There's a wiring diagram for 1987 tpi 5.0 here it's a pretty good diagram, except the wiring for the secondary fan is suspiciously missing from their diagram.

It would explain many things if the fans were just switched around. I.e. the primary fan plugged into the seconadary fans power cord, and vice versa. Technically, it doesn't matter which is which, as they are 2 identical fans, it just makes it confusing to work on them. The fan that comes on, when you ground the wire to the fan switch on the right cylinder head, should be the secondary fan. On my car, the secondary fan is on the passenger side. Who knows, maybe it's my fan that's plugged in on the wrong side.

When you ground that wire, which fan comes on? (driver or passenger side)?

As for the primary fan, there's 2 things that make the ecm turn it on during normal engine operation. The temperature set in the ecm chip, or a ground signal from the ac pressure switch we discussed before.

When you cut the wire to the fan switch, you connected it back in, right? That wire can be connected to your fan switch, and to your manual switch both. That would allow it to be activated manually, or as a backup, it would allow the temp switch to activate it.

This is not a nightmare. Nightmare is going to change the wife's transmission fluid, and having 3 drops come out after you remove the drain plug. Worse than nightmare is having to let the wife drive the firebird while you replace her tranny in your garage in January.

I got one idea I'll shoot at your rising tranny temp.
I'm assuming by tranny cooler, you mean you have the stock unit inside the radiator end tank. If you have something else, then my guess is way out in left field.

On the right side of the radiator, above the tranny lines, is a 3/4" hose for the heater core return. When the thermostat is closed, coolant returns to the radiator through this line. Water is always being pumped by the water pump, and the water that can't go through the thermostat, returns through this line instead.

Since you're now keeping the water in your radiator cooler, it takes less water to cool your engine. So your thermostat has probably closed down a little more. This means more (hot) coolant returning through that bypass line, dumping right in the top of the end tank, and running right down through the tranny cooler in the passenger side end tank.

 

to answer your question, when I grounded the fan switch the passenger fan was the one that came on with the car off and key turned on. The drivers fan did not come on. Now, the way I have it wired with the key on I can turn on or off the passenger fan and the drivers fan does not run but as soon as I crank the car the drivers fan starts running and I can still control the passenger fan on or off. Before, when I would crank the car up the drivers fan would not come on until the car reached a certain temp but now its always on.
Have a wired something screwed up?

why am I having cooling problems now? I never should have started messing with this seconday fan. My system was fine alls I wanted to do was put the seondary fan to use since it was just sitting there. My primary fan always runs now. why would cutting and splicing wires muck up my cooling system. when I really have only messed with 2 wires and one of those 2 is back to the way it was.
When I cranked the car up this morning the fan runs. The temp gauge does not move that much. After driving my 30 miles to work I poped the hood to see if the overflow tank had more fluid in it from driving and the amount was the same which means the radiator is not flowing coolant or I am to cold......the thermostat is not opening? I am at a loss.

Would jumping the green/white wire have anything to do with that?

even if I dont trun the toggle on, is the wire jumped somehow? and that is whats keeping my primary fan always on?

when I get home Im gonna just cut all the freakin wires that I spliced and see if I go back to normal.

 

to answer your other question about my tranny cooler. I have a temp gauge mounted inside the car and I can monitor the trans temp. I have a external tranny cooler mounted in front of my radiator. I have the trans fluid routed in series with the car radiator. The primary fan is always running, remember? now when I turn the secondary fan on my trans temp starts to rise, I can turn the fan off and the trans temp starts to drop. ..what in the hell is up with that?

 

Recheck the ac pressure switch. Make sure the gray wire from that plug is not grounded. Check for broken insulation along that wire as well, especially in areas of the wire that have recently been disturbed and or moved around. That is the only thing that could make that fan run ONLY with the engine running. Any other accidental grounds would cause it to run anytime the key is on.

Regarding trans temp:
What temp was it before?

What temp is it now?

Was this sitting and idling, driving in traffic, or cruising at highway speeds?

 

I checked all the wires that I messed with which is only 2 wires.
I messed with the black wire coming from the fan switch and the green/white wire coming from the relay.


I cut the wire that I had spliced into the green/white wire going to the toggle switch so now there is nothing different about that wire.
I redid the connection that I had on the fan switch black wire so that is now back to normal and has a good connection.
I crawled under the car again and made sure the fan switch ws connected and nothing was grounding it or messing with it.
I checked the high pressure switch and thats still the same, sitting there with nothing hooked to it.

I cranked the car up and the drivers side fan still runs and the car has been sitting for 6hrs.


What controls that ****in fan to make it stay on all the time?

 

I feel your frustration Wishmaster - I'm having fan issues myself right now. The best way to diagnose these problems though is to take out a voltmeter and get to prodding. There's a ground somewhere in there that you're missing.

The only thing that turns on your 2 fans are when some sensor, switch, rigged wire, etc. grounds the green/white stripe wire. If your fan is still coming on and the green/white stripe wire is not grounded - then you've got a bad relay.

Best of luck with your fan problem. My fan problem has been causing my A/C compressor to run at about 350 psi until it shuts off at 430 psi. Talk about a noisy compressor

 

When you were doing this, which wire under the hood was your 3 prong switch hooked in to? From the way I read this post I took it this way:

Switch prong:----->Connected to:
power-------------->12 volts postive
ground-------------> ground
ACC (output prong)-->(this is the one I need to know)


The problem with wiring the switch this way, is that this switch is not normally used for connecting ground, it's used for connecting power. When you turn that switch on, it connects the output prong (ACC) to POWER.

If that's the way this switch was hooked up, then power got connected to a wire we meant to be hooking up to ground.

If the ACC prong was connected the fan switch wire (should be black or gray), then when the switch was turned on, 12 volts was sent to the fan switch.

If the ACC prong was connected the the green/white wire, than 12 volts was sent to the ecm connector that provides ground to the primary fan relay, when the ecm wants the fan to be on.

I have a friend with an 87 Camaro GM service manual. I'll see if I can get him to scan and email me the page with the wiring diagram for 87 cooling fans. That information may be more accurate than what I've found on the web.

I can't help but think this has got to be something grounding somewhere it's not supposed to be.

 

Ive got everything back to the way it was before I started messing with the 2 wires but now my drivers side fan runs at all times.
from what your saying, could I have shorted out either the fan switch or one of my relays? How?

edit: ok after thinking about what you wrote. The 3 prong switch is not meant to ground it is meant to throw power to something? So what I would need is a 2 prong switch which is meant to ground a device? I hate to think but i may have shorted out 1 if not both relays? correct?

 

It wouldn't have shorted out the relay. It would have connected 12 volts positive on both sided of the relay coil. That won't do anything to your relay. However, at the other end of the circuit (depending on which wire you were working on) is either the ecm, or the fan switch.

You didn't answer my question. Which wire were you working with when you did the 3 prong switch thing?

After taking more time to think about it, i don't think that caused a problem. The primary fan is still off when key on engine off, but key on engine on, it is running. That means your ecm still has the ability to turn the fan on or off. Nothing else I can think of would cause it to come on with engine running, but not be on with the key(and engine off).

The only 2 things that make the ecm activate the fan are temp, and ac pressure. If it was a problem with your coolant temp sensor, I would expect drivability and starting problems, along with a good possibility of setting a code. That leaves the pressure switch circuit. The connector at the end may have nothing in it, but have you opened the loom and checked for a bare wire grounding out there?

Take a voltmeter and check for continuity to ground on both wires in the pressure switch. One should be grounded, one should not. If both test grounded, then that is the problem, and it's time to peel open the wire loom.

If we don't find it there, it will mean it's time to test at the ecm.

On a side note, you can still use the 3 prong switch. If you reverse the power and ground connections, it will throw ground to the accessory prong. The light should still work, as most lights don't care if they are polarity reversed (e.g. i believe some types of l.e.d.s are polarity specific)

 

ok, when I was messing with the fan switch wires to hook up to the 3 prong toggle. it was the black wire coming off the fan switch theirs only one. but I have that wire back to normal. I never messed with the pressure switch connection wires and that worked fine when I had A/C it would cut the passneger fan ON.


I went outside and disconected the primary fan relay and the drivers fan DOES NOT run when engine on. I switched with the secondary relay and the drivers side runs. So relays are working???

I left the primary relay disconnected and connected the wire back together that I have spliced into the green/white on the seconday relay running to a 3 prong toggle inside the car and I can ON/OFF the passenger fan at will.

Remember, I have only messed with 2 different wires. 1 on the fan switch and the green/white strip wire on the secondary relay.

I really do thankyou for all the help!

 

I FOUND THE PROBLEM!!!

I starting checking the A/C pressure switch wires a blue and a black. I never messed with those wires but noticed that one fo them was blue and I remembered that there was a blue wire up by the passenger fire wall that had a grounding ring on it and it was not connected. Hasnt been for years I guess since I took the A/C out but i really dont ever remember taking that wire loose from anywhere I had always wonder where it went.
Well, I grounded it to a bolt and reconnected the driver fan relay and cranked the car up and drivers fan did not run. So I also reconnected the wire that I had going to the green/white wire on the secondary relay. Turned the key to on and flipped the toggle and the passenger fan starting running. So far so good. I then turned the toggle off and cranked the car, drivers fan did not run so I let it get up to temp and the drivers fan kicked on and I checked to see if I still had control of the passenger fan and I do, it cuts on/off when I flip the toggle.

I really dont see how that blue grounded wire kept the drivers fan running all the time now when just last week everything was fine till I started messing with the fan switch wire and the green/white wire.


I also checked to see if sticking a paper clip in the pressure switch worked all along but it diidnt so I guess that is year specific...


I dont believe I got it! I have been so frustrated with this crap!

I never would have thought to even start fooling around with the pressure switch wire if it had been for you asking me to check the grounds on that connector.