1988 GT, V6, 5 speed, 12K miles: during A/C conversion to newer freon, still having problems with the radiator fan running continuously. Fan runs continuously, even when A/C is not selected. I have my mechanic doing this because I don't have A/C gauges and/or evacuation station. He has worked on Fieros before. We have tried the 3 trouble-shooting measures in the GM Fiero service manual: unplug coolant temperature switch, unplug hi-pressure cutout switch, disconnect A/C control head connector. Fan still runs. He even tried a different manufacturer's hi-pressure switch, but fan still ran. To verify the hi-pressure switch, he evacuated the system, so there was no pressure. Fan did NOT run. As soon as he charges the system, and it is under pressure, the fan stays on again.
Could we have the wrong compressor? Maybe one that puts out pressure that is too high?
Like many Fiero owners, we have chronic migraines from banging our heads against the wall, trying to diagnose issues. Any help would be greatly appreciated!
The fan running continuously will not present any problems. As soon as you turn the AC on that fan will energize and run continuously. On my 3800SC swap that I did 10 years ago the fan goes on pretty quickly and stays on. No problems so far. Actually when the AC is off. The radiator fan on the FIero is controlled only by a sensor switch on the engine.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 06-20-2021).]
If you installed the new style pressure switches, that could be the problem. A number of folks have had that issue. Don't know the cure other than to find the old style pressure switches.
Check the fan relay under the left headlight for a jumper wire.
[This message has been edited by fierofool (edited 06-20-2021).]
You only mention 1 switch, but there should be 2 in the rear of the compressor. What part number switches did you use, and what color wires are hooked up to each?
If you installed the new style pressure switches, that could be the problem. A number of folks have had that issue. Don't know the cure other than to find the old style pressure switches.
What are the old style switches? Are these the kind that the Fiero Store sells?
Should we replace the new switch with the one we removed?
The fan running continuously will not present any problems. [u][b]As soon as you turn the AC on that fan will energize and run continuously..
The problem is that the fan runs ALL THE TIME, even when the A/C is not selected. So, in cooler weather, the fan running constantly could prevent engine from reaching correct operating temp.
Having recently converted my system and researching the forums I found a thread that discussed cutting the ground to one of the two pressure switches (high or low) from the back of the compressor. If you do a search for AC pressure switch you should be able to find the thread. When I cut the ground it stopped the fan from coming on at settings other than AC or defrost.
". When I cut the ground it stopped the fan from coming on at settings other than AC or defrost."
Hope this helps!
Thanks for your input on what topic to enter into "search". I found several links to this issue. Most of what I found said to NOT cut the ground. If not grounded, the compressor will not kick on.
You only mention 1 switch, but there should be 2 in the rear of the compressor. What part number switches did you use, and what color wires are hooked up to each?
What is the correct color wire for the A/C cutout switch? (dark green?)
What is the correct color wire for the A/C high pressure switch? (black?)
What happens if the wires are switched?
[This message has been edited by sledcaddie (edited 06-29-2021).]
Finally! The shop that was doing my A/C conversion was able to diagnose the problem of the radiator fan staying on all the time.
The fan would not be running until the system was charged with freon. Then, it would run continuously, even with the A/C off. The issue was the compressor switch on the backside of the compressor. He had tried 3 other switches (different brands) with the same results of the fan continuing to run. Finally, he used the FourSeasons switch, and the fan only runs when the A/C is on Max, or the temperature sensor reaches a high enough temp to trigger the fan.
I hope this helps anyone else who has had troubles during A/C conversions. Thanks to all on Pennock's whose input helped us down the road to solving this issue. My Fiero is BACK!
Attached is a photo of the parts box for the compressor switch that worked properly.
