I am frustrated as I can not get anyone to figure this problem out. I have an 88 GTA stock that overheats in the summer BUT only when I run the A/C, I have changed the water pump,thermostat, the a/c compressor thinking it was dragging, the radiator, all the bottom air damns are in place and in good condition, the 2 fans are hooked up direct and i even changed one of the fan motors, about the only thing i have not changed is the radiator cap, the temp will pretty much climb up fairly quick in traffic and will boil over so i know the gauge works, now if i get on the highway it will eventually cool back down with the a/c running, this makes me think that the fans are not pulling enough CFMS at idle? but the car couldn't of overheated when new so what could be the issue?

 

Sure it's not overcharged?

 

If you mean the A/C? I don't believe so, it was done at a shop and the correct amount was added along with the oil.

 

I bet your fans aren't getting enough current to pull their rated CFM's. Lower voltage equals lower RPM's. Make sure your "direct" wiring of the fans is of the proper gauge and check/upgrade your charge wire from the alternator

 

Which fan motor did you replace? Both of them need to be 100%. They get old and slow down. The pass side fan is for the A/C.

 

I took a look at his car. Someone chopped up the stock wiring harness for the fans and bypassed the relays etc. <most likely because the previous owner cut the fusible link that powers then out> Were gonna replace the fusible links and rewire the fans. PCM grounds to the relays work. Voltages on the fans were like 10v and 9v for the other. LOL.

BTW, in the future if anyone has this problem, Probe the black/red wires coming out of the cooling fan relay/s with a multimeter while the fans are running to see if they are getting proper VOLTAGE. Also test the green/white wire going into the relay and see if it has ground from the PCM once the car has reached operating temperature <look at the temp gauge inside the car to average when your hot enough>

<Relays are located below the radiator fill cap on the TPI cars, on the GTA's on is on the passenger inner fender. Other cars may have them in diff positions.>

Watajob, btw good idea about the overcharged situation, not a lot of people know that will also overheat a car; but this is not his case <unless something changes after we fix the fans>. 91 1LE, Nail, Head .

 

While your in there re-wiring add another relay for another fan. You can add a pusher fan and add it to the front of the A/C condenser and wire to come on only when the A/C is turned on or just to a switch. I added one and it made a big difference. Its all about airflow. I have been itching to get one of those Taurus fans and see if they are as good as they say but havent found one yet.

 

Actually that front pusher is on a per situation base. You would be shocked to know how much those interfere with ac condensers and their ability to act as a proper heat exchanger when the real fans come on. Unless its properly controlled, it can actually hamper the condensers at highway speeds. Almost every car company turns off their fans at over 40 mph unless in a extreme over heat situation. unless i run some 1500cmf scirocco's or s blades. Regardless f cars cool very well when properly maintained.

And I have already went through this before. Imagine you going 100 mph and then hitting a 20 mph car. Your not going a 100 anymore. <yeah yeah you crash> same **** happens with air. Te he.

Like i said though, per situation base. Sometimes it will help one car and it will hinder another car. I mainly fall back on the pushers if the condenser is having flow issues that i cant fix other than replacing the condenser.

Thanks for the though though. BTW what are you using to control your 4l80? TCI unit? PCS, Comp? FAST?

 

I just got the vert a few years back and just started driving it the last 6 months. At 80 and faster it will slowly overheat. At 70 or less it will run around 180. I installed a pusher and an aluminum air dam and it is fixed. Like you said every car is different but ultimately it is all about air flow. I have a 4l80e but it isn't installed yet. The car I am going to put it in has a special suspension and it will take some fab work to complete. It makes over 600RWT and the 700 will not live. I would like to get OBDII for that car so it will all work off of one unit but I don't know who does those. First I got to get the trans figured out with the ford 9 huge torque arm rig I got from autoweldchassis.com You should check those guys out. They are not kidding about there rear suspensions at all.They would support a dump truck and make it hook.