wildviper44

ok so i recently bought a 91 RS and everything is pretty solid with the car, i can't complain....yet it does have an overheating issue. the guy i bought it from said that whenever the a/c is on it will make the cooling fan come on, thus the car will not overheat. yet it is november, and i do NOT want to keep the f***ing a/c on just to keep the car from overheating!!!! hahaha. please can someone tell me of an alternative (maybe some wiring option i can do or something) that i can make the cooling fan run independently? both my other camaros have cooling fans that are wired to an independent switch located next to my headlight switch in the cabin that i can turn on or off at will. in this Camaro, there are two switches but they are not wired to anything. i'm thinking i can use one of these switches to work for my cooling fan, can someone please tell me how to do this? i would think it should be pretty simple.... thanks

mjwadams

This is the exact problem I have with my 92 R/S. You can buy a generic fan thermostat from places like rockauto.com (sorry, don't have links).

Another trick I use in the winter is to set it to A/C but set the temperature to heat. You will get heat like normal but your A/C will run and keep your motor cool.

KNBlazer

Do you have dual fans or one big one? if you have two fans you can ground the one that runs off the switch, dunno which side it's located.... if you only have one fan, you can also do the same thing... that's how my bird is wired... fire the car up and the fan comes on.... or if you don't want to do that and keep the wiring as is, you can set up an independent switch with resistors and control at what point the fan or fans kick on prior to the control of either the switch or ECM...

Caveman305

iTrader: (8)

have you tried replacing the fan switch on the engine itself, thats what tells the fan to turn on when a certain temp is reached, you wont have to deal with turning on the fan manually

Apeiron

Why do you say it's overheating? Is it boiling over? What temperature is it getting to? What temperature does the primary fan turn on at? Does it get hot when it's sitting still? when it's moving? both?

Base91

iTrader: (1)

And running the a/c will make the engine hotter not colder.

Apeiron

It turns on the secondary fan, which will cool the engine if the primary fan doesn't run.

Base91

iTrader: (1)

If you're driving at moderate speeds in normal temperatures the fan shouldn't need to come on the emgine temp should stay fairly steady. Does it overheat (what temp?) when you're moving? If so you may have a problem other than the fan(s). Thermostat? Sludge in the block and/or rad? Running too lean? There loads of info on wiring up additional thermo switches and manual override switches. Either hooked in with the ecu or separate.

NufNuffZ28

iTrader: (10)

Is it a factory setup or is this carbed?

If you can't get the factory setup working right use a fan temp switch that you can put in your radiotor and use that.

Camaro305SB

Running the A/C does NOT cool the engine down. The other fan turns on but the engine has to work harder because the compressor is running, negating the little bit of faster air flow over the radiator/condensor. The A/C fan turns on to decrease condensor temp, not necessarily engine temp. Fans usually dont come on until over 220 on some cars, OP are you sure its even overheating?

I believe a 91 RS would be PCM controlled but correct me if I'm wrong

Bad idea to run something that draws that many amps though a simple switch. Let a relay turn it on, and the switch should control the relay.

Honestly, unless the OPs gauge is going to the top, I don't think there is anything wrong with the car at all.

eagle_eyes

iTrader: (3)

if you are wanting a manual switch, i wired my ground switch to supply the fan relay with a ground to turn on the fan using the same wire the ECM does. this way, if the computer wants the fan on, it will turn on, and/or i can manually turn it on the same way.

Dante93GTZ

iTrader: (5)

Cooling systems on these cars aren't complex...

Check:

Timing
Radiator
Hoses
Thermostat
Coolant Reservoir
AIRDAM
Fans (are the motor(s) good?)
Fan switch
Heater core (not leaking)
Heater core valve (on the valve cover)

If the engine itself is ok and the head gaskets aren't blown, you should be fine.
If the switch fails and doesn't kick on the fans, get a new auto-switch or wire up a manual one.

Only two cooling issues I've had with my thirdgens was (a) switch broke; replaced it, and (b) IROC was missing airdam.

Base91

iTrader: (1)

You haven't said what the engine temp is at a moderate steady speed on a normal temp day. If it doesn't stay close to what the thermostat is rated at then the fan(s) aren't the underlying problem. Ditto on eagle_eyes re the switch. It's what I've got but only ever need it between auto-x runs.

Dante93GTZ

iTrader: (5)

You should be able to trigger the fans as well by jumpering the 1&2 pins on the ALDL connector.

I used to use this trick between runs at the drag strip. It bypasses the switches and just kicks the fans on. I only used it when the engine was off, but it did work while on too.

NufNuffZ28

iTrader: (10)

I understand that and of course meant using a relay to do this. either way a radiator fan switch will work for this IF he doesn't wanna use the ECM for whatever reason...

Camaro305SB

Yes but he would need to tap into a low amp power source (NOT B+) for the control side of the relay.

51F1

I actually went to a garage one time because my fan never ran. They said the temp was normal and the fan turns on at 220. The gauge would sit at 200 or so

spade

iTrader: (3)

make sure you have an air dam please everyone always forgets about that... its very crucial to cooling a 3rdgen

Camaro305SB

Yea, thats normal. People think that 200-210 is hot when it really isn't. With a pressurized system and the correct mix of coolant/water it should even begin to boil until over 240.

Fourth gens are the same way. It was almost a 20 degree difference when cruising in my 93 LT1 Z. I took it off to replace the bumper cover and didn't re-install it. Boy was that a mistake.

hellz_wings

iTrader: (2)

dual fans, upgraded radiator, cooler thermostat, cooler fan on temps (set in the PROM), oil cooler, tranny fluid cooler, air dam, cowl induction hood... there's probly more..

but going from single fans to dual fans made all the difference.. I have only a 305 and i always overheated with single fan.

KNBlazer

it was probably your timing... and if you had it dead on, then it could have been your chain... if everything you mentioned was in place and working properly, then there is no reason why you would have heating issues... or at least I don't think ... ALL.LLLLLLL... ...

hellz_wings

iTrader: (2)

my engine is a 305 but heavily modified... the block is not stock in anyway.. (cam, heads, forged everything, 4* advanced timing, etc.) but is still a 305 (or 310 if you count the bored over 0.030).. Now it runs good at 160-180.. dual fans made overheating a thing of the past

rodsatheart

iTrader: (1)

Have you check the thermostat ? If the fan comes on normally try a diff. fan switch.
https://www.thirdgen.org/forums/cooling/236407-radiator-fan-switch-alternatives.html

kd5bwp

Mine runs cooler with the ac on. Typically about 20 to 30 deg cooler. Have switch out the temp sensor check the gauge with infrared gun and have installed a second temp sensor that goes into the radiator cap.
Replaced the
switch to turn on the fan
replaced the water pump
all hoses
heater core
thermostat
radiator
did a flush (was dirty but nothing too bad seen worse)
did a pressure check (checked out fine)
Fan will only kick on at 230+ and car will over heat. How do I know because the car starts to idle really bad and starts missing when it gets above 220. But If I turn the ac on then the fan on; it will keep the car under 210 in traffic. Never let the car go above 230 and normally try to throw water on the radiator when I get stuck in traffic (take the first exit when it gets hot and get to a gas station and throw water on the radiator not engine and let keep it running to cool off the block.) But on really hot days like we have gotten this past summer of 117 it would over heat if I got into stop and go or if I wasn't moving at least at 20mph. Air dams are also in places and I'm at a lost why this happens. Don't now if PO had engine rebuilt. But from the looks and mileage it's original 143,000.

KNBlazer

You need to run a lower temp thermostat, and make sure it has a hole so it allows the system to purge itself after filling it up with coolant... I never had a problem with overheating, the only times was when the timing was off... either ended up having to adjust timing or replace the timing chain... replaced the chain twice before going with a double roller... never had the problem again, well up until I forgot to plug the fan back in after working in the general area, but it only got up to 220 before I pulled over and plugged it back in....

hellz_wings

iTrader: (2)

Hahaha that's crazy... my camaro got up to 260 once (3 years ago) when the dumba** at futureshop didn't plug in the fan after he installed the alarm system! I overheated and radiator juice spilled out the cap... It was just about the burst but didn't thankfully (pulled over just in time). I plugged it back in and always double check any work that's one on my car that's not done by myself.

Back to cooling: Cooler fan switch (160 or 180* thermostat) and dual fans are a must for a performance engine IMO... I got a used 1989 trans am dual fans assembly for 100$ off ebay and I have a 180* thermostat... it's worked for the past 3 years perfectly and my engine stays around 160-170 in traffic, stop and go, highway driving, you name it.

Sonymaster20

iTrader: (3)

This will solve your problems

http://www.jegs.com/i/Hypertech/533/4028/10002/-1

If it is a TBI then this should get it. I got it and it keeps my car around 200-210. just perfect after replacing it.

luvofjah

iTrader: (2)

my 91 TPI 5 Speed has had no heating problems... I have Jet Hot coated Hooker 2055's, which I assume help it flow better which also keeps the heat down... My car is black and I live in FL... I removed my air dam, but I have a Knight Rider front nose with openings straight through to the radiator... never goes above 220... and if AC is on, it takes longer if it even gets to 220...