Hi guys i'm new here, i'd like to introduce myself and I have a huge prob I can't figure out. First off my name is Heath and I live in Central TX. I've got a Red 93 Trans Am I just got off a guy for 2k. I knew the car had a few problems and I have since fixed most of them except one. The cooling fans will not come on. I've done pretty much all the checks I can, replaced the relays, replaced the temperature switch in the water pump, tested the circuit from the ignition to the relay center to make sure it is powering up when you turn the key on and it is. I've checked both fans by direct hotwire to the engine and they both work great. The wiring from the relay's to the fans are not broken or damaged because you can take the top of the relay off and connect the circuit inside and the fans kick on, but there is nothing there to make the relay work on its on. Any idea's of what I should check next? ECU prob or somethin else maybe? Also when you put the A/C on it doesn't turn on the fan like its supposed to. Thanks ~Heath
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93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback,
on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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Do they come on when you turn the A/C on?
FYI the stock fan temp is 226 deg for low speed and 235 deg for high speed. The gage has to get pretty high before they come on.2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen" -
no they don't come on at all it was all the way in the red and no neither one comes on when the a/c is turned on either. The a/c is out of freon but I don't think it actually has to turn the compressor on for it to come on does it? I just jumpered the relay for now so they come on with the ignition switch. Just a temp fix but I really would like them to function properly and if there is anyway to do it make them come on at 190 or 195 instead of 220 or higher. I don't particularly like my engine's getting that hot especially an aluminum headed one. I've got a 69 mach 1 with 351w and aluminum heads and wouldn't dare let it get that hot since it got to 225 once and i ended up with a warped head. Thanks for the info though ~heath93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback, on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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You need a new chip burned with the fan on/off temps you want, or you need to add a thermostatically controlled switch to the system . What you called the "switch" in the water pump housing is not a switch, its a coolant temp sensor. The ECM programming deteremines when the fans turn on and off, based on the signal from that sensor. It also affects other ECM programming, like cold start enrichment.
GM designed the engine to run at temperatures in excess of 200*F. You will not damage the heads running in the 200-220* range. Remember, the LT1 engine runs "reverse flow" cooling, and the heads get the coolant first. So its not like your Ford, where the cold coolant hits the block, heats up and then hits the heads.
You can install a 160* T'stat, and reprogram the ECM chip for on/off temps in the 180-190* range, and have the ignition timing tweeked to take advantage of the cooler heads temps..... worht a few HP.
But you have to find out why the fans aren't running before you start modifiying the system.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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He's a good write up on what to get to do some cooling fan mods. But like they said above, it doesn't address why the fans aren't coming on in the first place.
http://www.thirdgen.org/coolTracy, 97 Formula, pretty much stock.
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thats a very informative write up wow, thanks for the info guys i will definately get on trying to locate the problem. On the ac the system had freon and the compressor was engaging when i first got the car but it apparently has a leak as the compressor will not engage does it have to engage the clutch for the secondary cooling fan to come on? I'm going to work on it some more this evening after work but for now i grounded the terminal on the relay that makes the fans kick on so one starts with the ignition. Temporary fix i know, at least until i figure out the prob. Thanks again ~Heath93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback, on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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Unless I'm mistaken (it's happend a couple times). If the A/C system isn't charged the A/C won't trigger the secondary fan since the relay is triggered by the A/C head pressure. No charge, no pressure. In my experience the secondary fan doesn't flip on until the engine is hotter than the surface of the sun or you turn on the A/C. Even with my t-tops off or when it's cool enough not to run the A/C, I run it in traffic just to keep that fan spinning. It does make a big difference. Obviously I havn't done the cooling fan mods or this wouldn't be a problem. It's on the to-do list.
Tracy, 97 Formula, pretty much stock.
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I'm going to suggest starting at the beginning of the line for turning the fans on. This is a check for the temperature sensor.
http://shbox.com/1/4th_gen_tech2.html#ect
A common mistake that I have seen is someone taking the temperature sensor out and putting it back in using Teflon tape. Since the sensor is on the water pump and I assume it probably has been replaced by now, I am wondering if they used Teflon tape on the senor which will cause it to give no reading to the PCM causing the PCM to not turn the fans on.2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen"Comment
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Originally posted by Jeff 95 Z28
ya know i put everything in with teflon tape *shrug* i only put it on about half the threads though do i still need to take it back out and take off the tape? Yeah the compressor isn't kicking in at all so i'm thinkin that maybe that would be the problem for the secondary fan.93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback, on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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You could test it using the chart in the previous link. If it gives you the readings you don't have to take it out. If it doesn't you need to take it out and take the Teflon tape off of it. The case has to ground to the engine. If you don't have a meter I would go ahead and take the tape off of it.Originally posted by Red93TA2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen"Comment
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ok update on this for everyone mostly myself lol, charged the ac system and now one fan comes on with ac but the other fan still will not come on. Checked the resistance of the new sensor i put in with the teflon tape on it and its fine resistances matched chart on that page that was linked. I didn't let it get completely hot because it will go well into the red without the fans on.93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback, on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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Sounds like you have a short somewhere between the ECT and the PCM. I would test the resistance at the PCM terminal. I believe it should be a yellow wire going into the PCM, but I'd find a wiring schematic for your year to verify that. Or maybe someone else here knows for sure. If everything there is good then you need to test for continuity from the PCM to the relay. If that checks out, something in the PCM has gone haywire, but that should throw codes. Are you getting any?
These are PCM pinouts for a 95, not sure if this is the same as a 93.
http://shbox.com/1/4th_gen_tech2.html#1995_pcm_pinoutsTracy, 97 Formula, pretty much stock.
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