rudyt5000

get a new fan relay...i had the same problem and i checked the thermostat and i broke a bolt on it. the relay should be between the radiator and battery it only cost like 5 bucks or something and will save alot of time in the long run trust me . now my fans turn on really nice ....

raul.garcia

Turning on the A/C will work only if there is enough head pressure to close the switch (if the switch is good.) The other thing you can do is disconnect that switch on the passenger side of the engine (since you can get to it from the top) and ground the wire, that's all the switch does so it should turn on the fan provided there' 12v at fan relay. Another method is to jumper the ALDL diagnostic A&B terminals, that will also turn on the fan. If the fan won't turn then look for faulty wiring, relay, and burnt fuses & fusible links.

Camaro_Boy

hey, ok well i replaced the sensor on the side of the passengerside of the engine and no luck. i will check for that relay because otherwise this will never end lol. i app all the help.. i hope for this problem to be resolved asap
any other things would be greatly app


thanks alot
Douglas

slimdawson

Obdi pcm must not use head pressure to close a switch. I have no ac and my fans still come on when I put the selector in the ac position.

78K5Blazer

I now have the same problem (or close).

Over heats (220) and no fan comes on.
Turn A/C on and the fan runs good and engine stays cool.
I took the wire off the switch on the PS head and touched it to ground - fan came on.

So I changed the switch on the PS head about 30 min ago. When it got to 220 and no fan I turned the engine off and came inside to read here. 'Wells' brand switch.

Could it still be the relay?

Why would GM put a switch in that works at 240 F? Is this so? If true, what stock vehicle had a switch in the right range that I can go buy tomorrow? I really do not want to put a manual switch in.

Thanks,
Doug

nj85z28

yea the stock switch comes on really hot-like over 240* but Jeg's has a 195* switch Just put in my car, made a world of difference

Camaro_Boy

well the fluid was coming outa the overflo lol... im accually going to try grounding the wire to find out if maybe the unit is faulty or not.. thanks again

Douglas

Camaro_Boy

doug, it has so much potential to be 100 things lol.. im going to try to have mine grounded and if it works im going to ninja or whatever his name is.. lol. sorry man u have helped me alot hah.. but ill try that.. so...

u should try to replace the sensor on the passenger side of the engine.. u might find it to be that

Douglas

Camaro_Boy

hey, i still havent solved this problem if it is not fixed by saturday it is going into the shop and i would like to save the money but what can ya do. it is overheating.. i couldn't find this "thing' beside the raditor and the battery whatever it was.. i replaced 2 sensors the "fan switch" between 6 and 8 and i replaced whatever the heck is on the water spout... i was wondering what a ecm is? could this be the computer that isn;t working or is it something else? im all outa guesses? and if it might be the computer... where exactly is it located? thanks again

as i said.. it did work for a little bit on and off.. so it could of the been computer if the computer effects the circuit...thanks again

Douglas

rudyt5000

let us know what it is in the end....i hate takin it to the shop cause thats just too much money ....but its worth it when you really just cant figure it out and tired of it ....but im still thinkin it might be the FAN RELAY lol...oh well http://thirdgen.org/techbb2/search.p...der=descending hopefully this helps you out ...just learn from other's who had the same problem

nj85z28

ok, of course the fluid was coming out, you shut the car off when the temp was that hot, so obviously the fan would not be on to cool it down. the stock switch tells the fan to come on at almost 240*! putting a lower temp fan switch in will solve your problem

Drkhrse89

If you have a dual fan setup and a TPI then you might want to look to replace the CTS (coolant temperature switch). I had the exact same issue where my primary fan was not turning on at all even after the 228* point. Then the secondary fan would finally turn on because it hit the 240* point. I replaced that and it was working again. The sensor is right underneath the throttle body next to the thermostat housing. Also the only real way to fix the running hot problem on these cars would to reprogram the prom. In a dual fan setup the primary fan is controlled by the prom and the secondary fan is controled by the air conditioning or true overheating. Also you will need to lower the thermostat temp in order to have coolant flow at the right temp. The Jet fan switch is a waste of money in my eyes, actually most of their stuff to me is a waste of money.

nj85z28

ok, drkhrse, have you tried it? because i have and it worked on my 89 TBI...and my car runs about 185*...... and it is alot easier to change than reprogramming **** left and right

IROC-T

I'm happy with my Jet fan switch,worked for me.

90rocz

Some more thoughts:
1)w/o a working thermostat, water will pass through the radiator too quickly to cool off and when it reaches a certain point, it will overheat badly.
2)you must make sure you have the correct water pump, some water pumps run clockwise, some counterclockwise, depending on which belts and pulleys you have.
3)Stock fans don't come on until at least 220*(for emissions)and 240* is not uncommon, when it hits 260* then worry.
4)If your radiator cap is bad, your coolant will boil-over at a lower temp.(plus it lets AIR into the system..)
5)You can use vinegar to boil out and flush your engine and radiator, will remove scale build up like cleaning a coffee pot.
6)Spoiler under radiator needs to be in place.
7)You can use a jumper wire at the cooling fan relay to test if the fan , relay & switch; if the engine is at 220*+ and you jump the relay(large red wire to ground)and the fan comes on, then the relay or switch is bad, fan doesn't come on=fans' bad.