Red87Bird

Hi guys.
I have a 1987 305 TPI Trans Am with dual fan setup.
The secondary fan won't turn on,even if I turn the AC on.I jumped the ALDL and only the primary goes on.I am going to change the relay but I suppose that the fan switch is disconnected .Is the 2 fan switch on the driver side of the car? I found something like the switch on the driver side near the manfifold with a green wire that goes close the A/C.
I am worried because on summer,in my country the weather reaches 42 degrees Celsius but my car neves goes over 230F.
Ah,on the passenger side the is an other "connector" near the manifold,is this the knock sensor?It is disconnected......

knight123

iTrader: (4)

couple things to help you:

- secondary fan can't be tested from the ALDL connector, only the primary
- secondary fan will only energize with the AC assuming it has a good charge and the compressor turns on
- the fan cooling switch is located on the passenger side way up under the manifold, the one closer to the oil pan is the knock sensor
- on the passenger side there is 2 wire connector going into the AC line, if you jump those wires the secondary fan should turn on. If not suspect the relay, fan or wiring to the fan. You can't leave this jumped as the PCM will throw an error if the secondary fan comes on with startup.
- secondary fan cooling switch is set to about 236F I think so you are basically overheating at that point.

knight123

iTrader: (4)

sorry, forgot it's an '87, you may have to trace the cooling line switch since it's different then mine.

Red87Bird

No problem , for your help ,I didn't know that jumping the ALDL the secondary one did not come on.
Thanks anyway

camaronewbie

I'm curious as to why this would throw a code, and what code it would throw.

Isn't connecting these two wires essentially the same as the A/C being on?

If so, I'm confused as to why the secondary fan being on at startup would throw a code - given that it's perfectly fine for you to leave the A/C on and shut off the car - and upon startup the secondary fan would come on immediately anyway - and that will not throw a code.

camaronewbie

Also, 236 is not overheating - these cars are designed to run warm. Overheating ONLY occurs when the coolant bubbles over - there is no real world set temp for that to occur - it's going to depend on pressure, ratio of coolant to water, cooling additives, and a whole slew of variables.

herbz28

iTrader: (1)

i am having the same exact problem with my car so i will be following this to see the outcome. Also red where in Italy are you? My younger brother lived in Italy for 2 years. He lives in Rho Gorizia Parma and a couple other places. And your motor is setup exactly like mine.

Red87Bird

I am In Foggia,Southern Italy near the Gargano promontory.
I ordered a new Fan Motor (ACDelco) and the relay.When it comes I will try to turn the A/C on and I hope that the fan switch is in my car and it runs.
Tomorrow I will post more photos with details.

knight123

iTrader: (4)

I never checked the actual code, but the check engine light would come on when I had it jumped. there is an input from the secondary fan relay to the pcm on my car and I think it expects to see that line change state to prove the circuit is working at some point, if it's grounded all the time the pcm can't verify the ckt is working. To get around this I added a hayes manual temp sensor to the radiator and had it connected to the relay switch lead and grd. I set the temp to 210 and now anytime it reaches that it kicks on the secondary fan (which also kicks on the primary fan on my car once the pcm see's the secondary turn on) they both run until the temp drops by 5 then turns off. Since this manual switch is in parallel to the AC the AC still turns it on if it's on. Now I have plenty of cooling and my engine temp never goes over 210. I still have the original switches in case the manual fails.

I know the cars are designed to run hot but that also does not mean the engine will last as long as if it ran cooler. As long as the car is in closed loop and the 02 sensor is hot enough the engine can run about 170ish and be fine with no ill effects. just my opinion.