91 Running hot

[91vetteman]

Just curious where to begin or go from here.
91 is running warm & the fan isn't kicking on till about 230-240 ?
Hard to tell exactly what the temp its turning on at since I dont have the digital reads. But it appears to be reflecting that temp at this time.
Some background when driving in normal conditions non-stop shes's about 160-180 roughly. But anytime in stop/go traffic she climbs up to about 230-240.
Been doing some reading on these forums already & purchased one of those fan temp switch comes on at 200 & off at 185. Well had it installed today & the fans still are NOT coming on any earlier ???
Also this might be a stupid question & excuse me if it is, but how do you know if you have true "dual" fans ?
I have 1 fan on the left (driver side) & another on the passenger side. Not sure if that one is just for when the a/c is on or not ?
I know to me it sounds like dual fans , guess one being the main & auxiliary .
Someone please enlighten me on that one becuase up to this point I havent got clear explanation from anyone.

So back to my original problem, what to check & where ?
Had someone check the radiator said it looked ok & didnt need to be cleaned.
Could a relay be bad somewhere or is there another temp switch thats faulty over-riding this new temp fan switch I bought ??
So right now I have a 160 thermostat which was just changed along w/my coolant so thats ok.

I appreciate any info you guys can provide. thx

 

[vetteboy86]

I have an 86 with one fan. It also has the aux. fan in front of the radiator. I know my girlfriends olds has a dual fan setup and one is for when the car gets to temp the other is when the AC is on. I dont really understand this because the dual fans are alot smaller than my one. I dont know how they expect a smaller fan to move as much air. Anyways to your question. I am sure their has to be a fan relay somewhere. I would start their. Have you let the car idle up to temp and physically see the fan come on? If so then once the first fan comes on, turn the air on and see if the other comes on. Once again i am not that familar with that setup. But for right now a physical insepection of their operation would be the first on my list. I will check in my manuals for the location of the fan relay.

Good luck
Craig

 

[91vetteman]

I have an 86 with one fan. It also has the aux. fan in front of the radiator. I know my girlfriends olds has a dual fan setup and one is for when the car gets to temp the other is when the AC is on. I dont really understand this because the dual fans are alot smaller than my one. I dont know how they expect a smaller fan to move as much air. Anyways to your question. I am sure their has to be a fan relay somewhere. I would start their. Have you let the car idle up to temp and physically see the fan come on? If so then once the first fan comes on, turn the air on and see if the other comes on. Once again i am not that familar with that setup. But for right now a physical insepection of their operation would be the first on my list. I will check in my manuals for the location of the fan relay.


Well your exactly correct both of the fans are small & I dont get the point in that set-up but anyway. It seems the only fan that does come on "period" is the drivers side , the passenger side fan never comes on whether the a/c is on or not. So im going to check the relays which are located up near the radiator. The other fan which now is almost acting like the primary & aux fan because it comes on at a certain temp which like I stated is about 230-240. Also the same fan comes on when the a/c is on ....weird isnt it ??
Dont get why the 1 fan is acting as both ..???

 

[VetNutJim]

The primary fan turns on at around 220.

The SECONDARY fan turns on at about 230 or whenever the AC is requested.

I think the design intent was to minimize electrical power consumption and squeeze the last bit of mileage they could get out of our Vettes.

It's a pretty good system EXCEPT you need to have a new chip made that will cycle the fans on earlier.
GM INTENDED these to run hot..hotter than I want mine to run.
Mine ran 230-240 in traffic until I did this. Not it rarely gets above 210 in traffic.

The RIGHT way to fix it is with the chip programming.
You don't have to get anything changed but the primary and secondary cooling fan activation and deactivation parameters.

 

[rrhayden]

I had a similar problem with a 92, and this is what I learned not sure if 91 is the same.



The ecm turns both fans on the first at 228 and the other at 235. You can check the fans by jumping the adl like you are retriveing codes. With the jumper in place, both fans will run with the key on ( not running). In my case the primary fan had caused the fusable link to melt, thus no fan. Replaced the fan motor, and link and all was well.



Good luck

 

[Hrtbeat1]

90's and 91's

We almost have a seperate breed of cars 90's and 91's. We don't have MAF's and use a speed density system. the relays are on the drivers side near the radiator shroud. There should be two of them mounted on a single mounting clip. rrhayden and VetNutJim are both correct. The computer controls when the fans come on (way too hot IMHO) and would need reprogramming to turn on at a lower temp. Jumpering the A & B (? I think?) terminals should let you know if both fans are working. There are many posts on the CAC about cleaning the radiator shroud (you wouldn't believe the birds nest you will find in there) which can help cooling a lot. You can also jumper one of the leads of the relay to ground and if the fan is good it will come on. (I can't remember which but I'll check mine when I get home.) Another thing you can do is jumper the two leads and run it back to a simple on/off switch with the other side of the switch going to ground. When you want the fans on flip the switch. Easier than reprogramming the computer unless you have the equipment to burn yourself a new Prom.

Like I said I will check my relays and post back later today.

Hope this helps

A hui hou

 

[Hrtbeat1]

Fan Relays

To check if your fans are operating jumper pins "F" of the relay to ground, with the key on the fan should come on. It could be as simple as the relay went bad, if one works and the other doesn't try swapping them. On my Vette pin "F" is a blue/black stripe wire, the other is blue/white stripe wire. These relays are readily available at most of your auto parts places, Kragen, Autozone, Advance, or NAPA.

Hope this helps

 

[91vetteman]

To check if your fans are operating jumper pins "F" of the relay to ground, with the key on the fan should come on. It could be as simple as the relay went bad, if one works and the other doesn't try swapping them. On my Vette pin "F" is a blue/black stripe wire, the other is blue/white stripe wire. These relays are readily available at most of your auto parts places, Kragen, Autozone, Advance, or NAPA.

Hope this helps

Just wanted to put this "Thread to Rest" sorry for the delay, especially to those who threw out some advice. After I installed the fan switch , the main man himself which some of you might know as "vette tech" connected the leads to both relays . Now I have both fans operational at 200 F , this is a DEFINITE improvement compared to what it was running at.

Thx again for the assist gang ~