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I just got a 91 Z28 350 auto. It has an aftermarket radiator with aftermarket twin fans that are wired together. No name on fans. When I apply power to the wires only one fan comes on. Is it possible/probable that the second fan has an internal temperature switch? Haven't had it on the road so I don't know if I have a problem. I know I should probably wait and see but if I have a problem it's a lot easier to fix now that I have the radiator out of the car. The fan does come on when I turn the a/c on (low pressure switch jumped). Should each fan be wired separately. They are now wired to the wires shown circled in red. Both sets of wires have a black wire & a black wire w/ red stripe.
They look kinda inadequate... like ebay $10 specials.... Im guessing the one that doesnt run is dead or something is wrong with that wiring.... they should be run separate too.
No shroud etc... the wires look thin so I don;t think they pull much current which is the only plus..... I doubt it has any kind of internal temp swatch
id dump those and go LS fans! ...even a stock single fan should cool better.
if originally it had only ONE wiring harness for a single fan, i don;t think its a 350 unless it was swapped.
VIN verifies a 350. In the pic with the wires there are two sets of wires. That's why I was wondering if it is supposed to be wired for two fans individually. One for a/c and one for the hi temp. Would it matter which fan is on the left or right? Any pic?
Driver's side fan was ECM controlled from the factory. Passenger side fan turned on with AC or via activation from a temperature switch in the passenger side block / head, can't remember precisely but it's up in that area. Both were hooked up to relays since they draw substantial current, schematics are available in the factory service manual.
There is what looks like a broke off temp switch in the right side head but I didn't see any wire around. Does that wire come up from below by the starter?
VIN verifies a 350. In the pic with the wires there are two sets of wires. That's why I was wondering if it is supposed to be wired for two fans individually. One for a/c and one for the hi temp. Would it matter which fan is on the left or right? Any pic?
Factory, the two dual fans were wired separate and had separate relays.
From what i can recall.... on early dual fans.....the passenger side came on when the ac came on, or when the car got to a certain temp and the computer commanded it on.... then the secondary driver fan would kick on via a coolant temp sensor in the passenger head depending on engine temp.
I read that on I think 89 - 92??? both fans came on for the ac since it made the ac work better. but the fans were stil controlled separately for actual cooling.
I swear there was a more detailed tech article about it but I found this:
I can get pics of the original TPI dual fans and a Ls1 dual fan since I got both lying around. .
The Ls1 fans will plug right into the TPI connectors as the motors are the same physically.....BUT they do suck more energy as they are internally different and pull more amps than TPI fan motors....... My compromise so far is a LS1 fan shroud but with the TPI fan motors since they drop right in.... even the fan blades themselves are the same! .
IMHO though, if you are going to go and get original stuff, id just upgrade to a set of LS1 fans.... the shroud pulls / directs more air. for better cooling vs the shroudless TPI fans.. .
Just beware of the extra power they draw and consider using the TPI fan motors.
There is what looks like a broke off temp switch in the right side head but I didn't see any wire around. Does that wire come up from below by the starter?
My 87 had a single fan... but had the wiring for a daul. The connector was in the same harness as the knock sensor. The fan switch was.... between 6 and 8
If I went to a junk yard and found one that would match up to my radiator I could get the pig tail that I'm missing? Would most newer than 91 fans/shrouds out of a v8 work good enough?
I would start by defining how / when you want your fans to run, then come up with a wiring game plan based on what's left in your engine bay. The factory harness will only be a substantial benefit if you're running a stock setup, otherwise you'll have to mod it and might as well just start with fresh wires.
Ls1 shrouded setup is pretty popular for upgrades.
If I went to a junk yard and found one that would match up to my radiator I could get the pig tail that I'm missing? Would most newer than 91 fans/shrouds out of a v8 work good enough?
There's all types of fans... and any would work really....you'd need to get creative with the mounting depending on the design.... I personally found the LS1 fans fit perfect. For me, it slides right into the base by the radiator and I modified a stock upper radiator bracket to hold it in place so it al look's stock. .I saw some people found them to be a "nightmare" to put in??? For me, someone with low fab skills, i found it extremely easy. Just a little trimming etc....
I'd just do 4th gen F-body V8s for simplicity though.... the motors are all more less the same physically and the connectors are all the same as well..... (you can buy connectors new but they are expensive)
93-97 LT1 fans are the same basic design but are thicker than Ls1 fans and would need more work to fit in. They use either TPI or Ls1 fan motors depending on the year... .blades are also the same as LS / TPI fans... the fans can be removed individually from the shroud though so technically easier to service.
98-02 V6 and Ls1- V8 fan shrouds are the same physically as are the blades.....but the v6 use smaller powered motors and actually look a little different but use the same connectors..... But the shroud is what you really want.
You can see mine in #4..I put a pic for both LS and LT1 fans
Personally mines al weird lol I got them to come on at the same time etc. etc.. .my second fan is on its own circuit blah blah etc... I added a manual fan switch for lower temps yet also kept the computer control as a higher temp back up and got a third fan in front....
Side note, tons of 90 - 2000s GMs used the same connector.
I don't know if the wiring works. I have to find the wire that goes to the coolant temp sensor on the right head. If I ground that wire would that turn on the fan if everything else is correct?
Theres usually a big connector where your wires are cut. that connector plugs into a harness for the single or dual fan....91 should be the same.I think... the ground wire to the fan switch is part of that connector...
Its possible part of the wires that goes to the fan switch is in the remaining part of harness somewhere...they just cut it I'm sure .If you pull on it, it wil lcome out, but im guessing they just cut it.
Those fans on there now wont work as theyre not jhooked up properly though.... but tes, the relays should have power with key on. if you had the fans wired properly and found the fan switch wire,...the fan would activate when the wire is grounded.
You'll need to kinda rebuild your harness....I've seen the fan side of the harness available new on ebay before
You get the the fans from any 98-02 Camaro or Firebird. These are “LS” fans.
the shrouds and fan blades are the same for V6 and V8. The motors are smaller on the V6 units though. The v6 technically aren't "LS fans" cause of the motors being smaller........ but are the exact same thing shroud / blade wise....all .....aside the motor…
the motors are removable and you can out in practically any motor you want…TPI, LT1, LS1, 3.8 etc…
The fan wires up by the battery/radiator do not plug in to the harness. They are part of the harness. My fan relays are on the firewall left of the master cylinder. Both relays have power with key off. I tested both with a meter and they are both functioning properly. When I jump them I get power at the fan wires by the radiator. One relay per set of wires. I can not get power to the fan wires with out jumping the relays. Key on, a/c on with low pressure switch jumped. A/c clutch engages but no power at fan wires.
A large wire loom goes across the top of a/c evaporator towards the engine then down. It T's at about the intake & valve cover then towards the front of the engine. I peeled back the large loom where it goes down & the one on top of the engine and I can not find any wire that would go to the coolant temp sensor for the fan. I have a manual on the way. From what I've read the coolant temp sensor wire is yellow. Correct me if I'm wrong. I know it has to be there somewhere. Ideas?
"The fan wires up by the battery/radiator do not plug in to the harness."
Yeah, it looks like the PO cut the wires right before the connection. There would be a removeable connection in that area unless the newer models didn't have it.. I noticed that I only see 87 and then 88-89 dual fan connections available new......maybe yours was integrated into the whole harness by 90.
" I can not get power to the fan wires with out jumping the relays. Key on, a/c on with low pressure switch jumped. A/c clutch engages but no power at fan wires"
The fan takes a while to come on with the ac on as it reads the pressures.... the sensor in the hard line on the frame rail wil lturn it to come on and will have it come on when disconnected... but im not sure if there would be any delay in signal.
"A large wire loom goes across the top of a/c evaporator towards the engine then down. It T's at about the intake & valve cover then towards the front of the engine. I peeled back the large loom where it goes down & the one on top of the engine and I can not find any wire that would go to the coolant temp sensor for the fan. I have a manual on the way. From what I've read the coolant temp sensor wire is yellow. Correct me if I'm wrong. I know it has to be there somewhere. Ideas?"
On my 87, it connects from the connector into that large loom, and then goes with the knock sensor wire down towards that area.. .wire is black. I heard they are all black regardless of year.
have you tried checking the wiring for the knock sensor? Have you also found / seen the old fan sensor?
I thought the knock sensor was up by the intake. Where is it? I saw a pic of the coolant sensor, the wire was green. The schematics I saw say yellow. I don't know.
I thought the knock sensor was up by the intake. Where is it? I saw a pic of the coolant sensor, the wire was green. The schematics I saw say yellow. I don't know.
Knock sensor is by the starter / below the fan temp switch. They both use the same connector....you can only see them from the bottom of the car really.... the fan switch is in-between the spark plugs right under the exhaust manifold if its still there. ....The relay ground is green i think..
any color is possible really due to varying years/ what the owner did...........but im banking on the wire being black or green if its still there...
" coolant sensor,"
you could be looking at the sensor for the ECM which is on the manifold 9this i believe controls the main fan #1 through the ECM).......you're looking for the fan switch for the secondary fan
I was thinking the wire came down from the top. My bad. It has headers on which is probably why the sensor is broken. I will have to get the car on ramps to get underneath and take a look.
I was thinking the wire came down from the top. My bad. It has headers on which is probably why the sensor is broken. I will have to get the car on ramps to get underneath and take a look.
its possible... i mean they change wiring al lthe time ec.. lol
Im gonna guess though that its stil in the same place as older cars... so part of that harness you showed.
if you can look around down there by the old fan switch though you might find remnant's or leftover pieces of it.
My guess is they thought they could wire both those fans into the primary fan wiring and eliminate the second fan's wiring.
i got LS1 shroud mounted with TPI fan motors. I had LS1 motors but I felt they sucked too much juice. I don;t rally notice any difference with the TPI vs Ls1 motors in the shroud really as far as cooling / fan force... the Shroud though makes a difference as it pulls air through the radiaor and condenser more efficiently. the Ls1 motors should turn faster but the TPI motors work just fine for me.
I got a slightly lower fan switch running both...they go to the switch in the head. I spliced he wiring so both go on at the same time.... and the fan switch I got is set lower than the ecm.... but I have the ecm control as a back up in case the switch fails and also since it activates the fan for ac. So the fans come on at i think it's 220- 230 now (just slightly past the halfway on the gauge) and turn off just under the halfway point....
if the switch fails, there is the ecm control which is... was it on at 245???
Fans come on and cool down / turn off within id say 1-2 min max. With the single fan, the fan would stay on a bit longer....with the TPI shroud-less dual fans, I felt they actually worked less efficiently than the single big fan. the LS dual fans sound like the TPI dual fans (same blade afterall) but they are more quiet than the single fan but cool way better than the dual TPI fans.
I have an aftermarklet SPAL pusher on the front as an emergency fan but it is sooooooooo loud..... Im happy I got the duals to work properly. That SPAL is set to come on after the Ls1s or around the same time in extreme heat as I used the same switch number (TS85) but in a different location.
just wanted to give testimony on how good the LS fans work and some ideas with what you can do with your fans.
I found the wire. Took the sensor to the parts store. They didn't have anything even close. Went to the dealer. There was a change. Need the new sensor & a new plug/wire to match. Supposed to be here Wed. Fans/shroud is supposed to be here then two. The new a/c condenser fit perfect. The radiator mounting tabs are just a little tall but size seems appropriate. Core is 2 1/4" thick. Hopefully things will go back together good. Thanks for all the help.
I found the wire. Took the sensor to the parts store. They didn't have anything even close. Went to the dealer. There was a change. Need the new sensor & a new plug/wire to match. Supposed to be here Wed. Fans/shroud is supposed to be here then two. The new a/c condenser fit perfect. The radiator mounting tabs are just a little tall but size seems appropriate. Core is 2 1/4" thick. Hopefully things will go back together good. Thanks for all the help.
Nice!! Post progress!
Im surprised they didn;t have a fan switch though. its a common GM fan switch napa has them.
I put in the new coolant sensor today. I grounded the wire first to see if I got power to one of the fan wires at the radiator (engine off) and it did not but I didn't leave the key on very long.
I put freon in the a'c and got the compressor to come on. It didn't seem to cycle off & on but the engine was starting to warm up so I had to shut it off. No radiator in yet.
It looks like they are ls fans, correct? If they are what wires do I need to upgrade? From the fan to the relay & from the relay to the battery? I think I would rather get closer to original so I don't have to mod anything and just swap motors. Will most any fan motor from mid size car with a v8 mid 80's to early 90's dual fan work? How can you tell the diff from v6 vs v8 fans?
I put in the new coolant sensor today. I grounded the wire first to see if I got power to one of the fan wires at the radiator (engine off) and it did not but I didn't leave the key on very long.
I put freon in the a'c and got the compressor to come on. It didn't seem to cycle off & on but the engine was starting to warm up so I had to shut it off. No radiator in yet.
It looks like they are ls fans, correct? If they are what wires do I need to upgrade? From the fan to the relay & from the relay to the battery? I think I would rather get closer to original so I don't have to mod anything and just swap motors. Will most any fan motor from mid size car with a v8 mid 80's to early 90's dual fan work? How can you tell the diff from v6 vs v8 fans?
I'lll break it down a bit so its easier to cover some points:
1. Yup, those are LS fans. the factory 3.8 motors are a bit smaller and look different. The 3.8 motors are a bit shorter and also look less than a cylinder like those motors do so you should have Ls motors unless they were switched but we wont go into that lol
2. If you are using the stock wiring and get that up and working....., then you can splice in the correct gauge wire...i think it is 12 or 10... from the cut ends to the connectors which would plug right into the fans.
3. i'd take a look at the fan tech article here as it describes how the systems work....i think the fan operation are a bit different for 90 - 92 models...I think i recall both fans come on when the ac is on on the 90-92..... So Passenger side is activated by the ECM wen coolant is hot... Driver fan is activated by the fan switch in the head when it reaches a higher temp... and i THINK both come on for ac for yours.car (dont quote me on that)
4. Grounding the fan switch with the key on should complete the circuit for the second fan relay... that relay would then send power to the driver side fan.....try take a look at that relay. I beleive it should have power whenever the key is on as should the passenger fan relay.
5. AC pressure makes the fan come on at I think 230? PSI... so itd take a while to turn on..........from cold start my car takes a good minute - 3 before the ac turns the fan on.
- The ac pressure sensor in the hard line on the passenger frame rail would make the fans come on when disconnected almost immediately when its unolugged when the car is running.
if all else fails you can just create a stand alone harness for the fans using 2 relays.
"The primary fan is controlled electronically through the ECM (Electronic Control Module). TheEPROM (or “chip”) is programmed with a fan turn-on temperature of 222° F or higher, depending
on year, or when the A/C head pressure exceeds 232-psig as long as vehicle speed is below 35-
40 mph.
The secondary fan is controlled two ways, depending on year. In 1987, an in-cylinder head
thermal switch is used. This switch engages the fan when coolant temperature reaches 243° F!
An A/C head pressure sensor is used in addition to the thermal switch in 1988 through 1992
which turns the fan on with the A/C."
What i'd do is try to see if you can get the system running correctly as it was stock...
then from there you can do stuff like have them come on the same time ets... etc... custome stuff.
"The fan wires up by the battery/radiator do not plug in to the harness. They are part of the harness. My fan relays are on the firewall left of the master cylinder. Both relays have power with key off. I tested both with a meter and they are both functioning properly. When I jump them I get power at the fan wires by the radiator. One relay per set of wires. I can not get power to the fan wires with out jumping the relays. Key on, a/c on with low pressure switch jumped. A/c clutch engages but no power at fan wires.
A large wire loom goes across the top of a/c evaporator towards the engine then down. It T's at about the intake & valve cover then towards the front of the engine. I peeled back the large loom where it goes down & the one on top of the engine and I can not find any wire that would go to the coolant temp sensor for the fan. I have a manual on the way. From what I've read the coolant temp sensor wire is yellow. Correct me if I'm wrong. I know it has to be there somewhere. Ideas?
It kinda sounds like everything should work fine.
The question is only the fan switch wiring which you mentinoned above didn;t work correctly....... when it is grounded, that relay should close and send power to one of the fan wires...
Try double check the point you are grounding etc...
Good read. Yours & the article. I'll recheck the ground & the a/c pressure sensor tomorrow. The guy I'm getting the fans from wasn't real clear if he was including the wires. I begged. I don't have the wires to the fan so if he doesn't include them I'll pick some up from an ls when I'm at the salvage yard.
Good read. Yours & the article. I'll recheck the ground & the a/c pressure sensor tomorrow. The guy I'm getting the fans from wasn't real clear if he was including the wires. I begged. I don't have the wires to the fan so if he doesn't include them I'll pick some up from an ls when I'm at the salvage yard.
You can buy them new at napa but they are oddly expensive. and the wire is surprisingly short for how much you pay......and they fit ok but not as good as a GM one. You NEED a good one though as the connector wil slide right off without the locking tab....
You can check any Late 80s to Mid 2000s GM. Most should have it.
I found some on a late model impala with the 3400 in it. One fan motor looked different but the connector was the same. I pulled the wire as far as i could go and got maybe 2?? feet of wire on the connector.
SIDENOTE
The LS shroud makes it hard to disconnect the fan motor plug cause it makes it kind of recessed and I can't even fit my thinnish fingers in there to unplug them. you should have plenty of room from the bottom of the car but its impossible to get them off easily..........I had to pull the fans so many times for other stuff so I made the wires extra long so they came up with the fans and i still had to use one of those picks to get in there and remove the locking tab once i had the fans out.........
I cut the bottom of the shroud housing where the plug goes, as well as the very bottom fan "guard" so i can easily unplug the connectors should I need to pull the fans again........
I wish I did it sooner when I was putting in and polling the fan out so much earlier this year... now that I actually cut it I probably wont have to pull them ever again lol
The a/c compressor cycles on and off as it should.
Engine running: I have power at the primary fan wires (black/red stripe). It doesn't matter if the temp switch is plugged in, unplugged or grounded. Nothing changes.
A/c running: if I disconnect the a/c pressure sensor in the hard line from the condenser to the evaporator nothing changes. I do not get power to the secondary fan wires (black/pink strip) no matter what I do. Exception: I get power to the secondary wires only when I jump the relay.
Now the service engine light is on and it runs ruff. I looked for a vacuum hose or wires off but they are all connected.
I found some cut wires.
The plug has a red wire cut off going into plug and coming out of plug, circled/arrow in red.
The red wire that runs through plug is cut at the green circle and has power with the key off.
The a/c compressor cycles on and off as it should.
the compressor shouldnt be cycling?.... I mean it DOES but in short operation it shouldnt be cycling if it has a full charge. Seeing as you don;t have fans installed yet though, if its cycling in that short ioperation time, im thinking theres not enough refrigerant? It wouldnt send a signal to turn the fan on if its cycling I think as it wont build the proper pressures?
Engine running: I have power at the primary fan wires (black/red stripe). It doesn't matter if the temp switch is plugged in, unplugged or grounded. Nothing changes.
Maybe someone grounded it to be on at all times... is there a switch anywhere on the dash etc? Youre talking about the ecm temp switch correct? Not the fan switch? the ECM sends the signal for the primary fan.
A/c running: if I disconnect the a/c pressure sensor in the hard line from the condenser to the evaporator nothing changes. I do not get power to the secondary fan wires (black/pink strip) no matter what I do. Exception: I get power to the secondary wires only when I jump the relay.
Overall it sounds like the car has several wiring issues unfortunately. I think the best thing to do is get the radiator and fans installed so you can run the car longer and do diagnosis without worrying about the car overheating etc...
Now the service engine light is on and it runs ruff. I looked for a vacuum hose or wires off but they are all connected.
I found some cut wires.
The plug has a red wire cut off going into plug and coming out of plug, circled/arrow in red.
can you see what the other wires go to?... i dont think those would be related to the fan though... pull the codes for the SES light.
i'm thinking the former owner ditched the OEM fans and decided to install those two small fans... they didnt cool enough so they somehow wired the primary fan to be on constantly. (mine was on..turned out to be a short in the wires at the relay cause they were al lcorroded)
Id sort out the coolant temp circuit before the ac fan operation first.
Try look at the primary fan relay. ground wire ..... I THINK its the same color as mine... so the relay ground wire would be green with white stripe. Try trace it down. My guess is that they grounded it somewhere
Mine is connected to the ECM and I added a fan switch circuit so it comes on via the fan switch in the head first. ... if it were grounded directly to something it would be on constantly.
As for the secondary fan switch activated fan... regarding it not getting power when the fan switch wire is grounded... trace the ground wire back to the relay... it should be simple. it could be cut or broken in between the switch and relay.. if thats so, just wire in a new wire to the fan switch.
You;ll find the issue. You'll just need to dig a bit deeper to find it.
.. is there a switch anywhere on the dash etc? Youre talking about the ecm temp switch correct? Not the fan switch? the ECM sends the signal for the primary fan.
No switch on dash. I talking about the temp sensor in the right side head.
.. is there a switch anywhere on the dash etc? Youre talking about the ecm temp switch correct? Not the fan switch? the ECM sends the signal for the primary fan.
No switch on dash. I talking about the temp sensor in the right side head.
. pull the codes for the SES light.
I don't have a code reader. Can you suggest one?
That switch in the head should activate the secondary fan wires (Im thinking you got a broken or cut wire between that secondary fan relay and end of that switch wire wire, but focus on the primary fan first...). Since the Primary fan is ECM controlled its possible it works fine I think the sensor in the intake manifold below the thermostat tells the ECM the coolant temp and from there the ecm grounds the fan to come on. Cheap 2 pin connector sensor that sticks straight out...id just replace it now since you have everything apart for extra insurance. It COULD be...... but I DONT THINK ITS TELLING THE ECM THAT YOU HAVE A HOT CONDITION ALWAYS THOUGH.. it sounds like the relay is grounded to be on so im thinking someone wired it directly to ground (see previous post)
There are code readers for OBD1 but you just need a paperclip as it does the same thing basically... Put the two ends of the clip into the ALDL connector under the dash somewhere... it would go into ports A and B... if you look at the connector head on, that would be the top right 2- ports right next to each other. make sure the paper clip is jammed in kinda tight and making contact with the metal pins...... Turn the key to the on position (but don;t start the car) the SES light will flash codes like Morse code. You will first get 1 flash, followed by a pause, followed by 2 flashes to indicate code 12 which is always there showing the ecm is operating that would be followed by whatever codes are in the ecm and it just repeats code 12 and the other code
12 - 23 - 12 -23 (its saying code 12 meaning the ecm is operating and code 23 meaning it has code 23 stored and then it repeats 12 and 23 till you pull the paperclip or turn it off)
Looks like I have some things to check out. I want to replace the power steering pump before I put in the radiator so it might be several days before I have that done. I will check the wires for brakes & grounds. Thank you so much. I'll report back.
Looks like I have some things to check out. I want to replace the power steering pump before I put in the radiator so it might be several days before I have that done. I will check the wires for brakes & grounds. Thank you so much. I'll report back.
no prob!
DEFINETLEY do it while you have the radiator out....im wishng i did mine earlier as well
I was looking under the dash right side and found a few drops of antifreeze. GREAT. So I have a new heater core now. The dash has a plastic cover on that covers the badly cracked dash. This car isn't the gem I thought it was but when I get it all done it will be. I have the power steering pump out.
I was looking under the dash right side and found a few drops of antifreeze. GREAT. So I have a new heater core now. The dash has a plastic cover on that covers the badly cracked dash. This car isn't the gem I thought it was but when I get it all done it will be. I have the power steering pump out.
New coolant sensor in intake by thermostat.
I didn't find any wire that was grounded/spliced.
Ugh.. heater core... its not as bad as it seems though. ...Im not sure about camaros... but for Firebirds i was able to remove the top heater box bolt by using a flexible extension... it was actually super easy.. .the HARDEST part was removing the hoses nd this was back in 2002 when I didn;t know about inserting a pick to break the seal etc.. or much about cars lol
I think the easiest would be to get some fans installed and see what happens / how it operates. Could be a short in the wiring / relay somewhere?
Power steering pump is supposed to be in tomorrow morning. I should be able to get the radiator in and running tomorrow. I'm keeping my fingers crossed.
03-23-2022, 01:20 PM
