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sledcaddie
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MAY 04, 10:19 AM
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| quote | Originally posted by Patrick:
If your engine is not warming up properly... the thermostat has probably been removed or it's stuck open (or it's been replaced with a lower temperature unit). The fan running continuously would make no difference to the warm up period if the factory 195° thermostat was installed and functional.
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Well, the thermostat is there, and it's closed. My next step is to disconnect the fan switch wire to see if the radiator fan stops.
Another thing might be a bad sending unit for the temp gauge. The gauge flips wide open when you turn the key, then goes back to cold. After driving awhile, the heater blows hot air. So, maybe it just 'appears' to not be warming up (on the gauge), but actually is warming up.
If I replace the radiator fan switch and the temp gauge sensor, do you use teflon thread tape, or not? I've read that the threads must ground to the block, so no tape?
Diagnosing a Fiero. Always a fun challenge. It really helps having this forum to learn from!
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fierofool
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MAY 04, 04:25 PM
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The gauge sending unit is in the trunkside head near the coil. Be sure someone hasn't been duped into converting to the 'new style' sensor with the oval head. It should be round with a slit in the side of the plastic head.
No teflon tape required on either temp or fan switch. They do ground through the threads. The coolant temperature sensor underneath the thermostat housing neck can be wrapped with teflon, though. That sensor is for the ECM to adjust air fuel mixture.[This message has been edited by fierofool (edited 05-04-2021).]
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DukeHog
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MAY 04, 09:10 PM
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The previous owner of one of my cars put a jumper wire into a relay that is under the trunk carpet near the blower motor for the coil/alternator. I know that it made the coil blower motor run continuously but I believe that it also made the radiator fan run. I can't remember for certain. It may be something to check if you can't find the problem elsewhere. [This message has been edited by DukeHog (edited 05-04-2021).]
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sledcaddie
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MAY 05, 09:37 AM
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I disconnected the wires to the radiator fan switch, but the fan continued to run.
I didn't see any extra wiring, like a 'jumper' on the relay, in front of the left side headlight. I replaced it with a new one earlier. As an 88 does not have the rear blowers for the distributor/coil, there would be no relay in the trunk area.
I'll try to see if any wiring at the radiator fan has been tampered with.
I'm running out of options. Fiero issues are sometimes very frustrating![This message has been edited by sledcaddie (edited 05-05-2021).]
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sledcaddie
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MAY 06, 06:16 PM
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| quote | Originally posted by fierofool:
No teflon tape required on either temp or fan switch. They do ground through the threads.
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I just received a new, lower temperature, fan switch from Rodney Dickman. The instruction sheet states that you should use Teflon tape on the threads. Which is it?
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Patrick
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MAY 06, 07:19 PM
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| quote | Originally posted by sledcaddie:
The instruction sheet states that you should use Teflon tape on the threads. Which is it?
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This isn't rocket science. I do two or three wraps of Teflon tape. It's thin enough that the high points of the fan switch thread easily cut through the tape and ground the unit to the engine.
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pmbrunelle
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MAY 06, 07:40 PM
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You need something on tapered pipe threads.
Often sensors come with pre-applied sealant in the package; in those instances, you can apply nothing. The pre-applied sealant is only good for the first time you screw the sensor in.
If the sensor is dirty/used, wirebrush the threads clean. If new, you can skip this step.
Then, you can apply Teflon tape or Teflon paste, and install the sensor.
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sledcaddie
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MAY 06, 08:25 PM
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WELL!.... As a typical last resort, I turned to the handy-dandy GM service manual. In section 8A-31-6, it gives a trouble-shooting process for when the fan runs continuously. A possible culprit could be the A/C high pressure control switch. As I had the A/C converted to the newer freon last year, this might be it. It also goes on to say which colored wire might be shorted to ground, causing the fan to run. It is always personally gratifying when I can correctly diagnose the "gremlins" that infect our favorite cars. I hope to complete this process this weekend.
The reason this is taking me so long is because my Fieros are stored in the spare garages at my brother's house, which is a few miles away.
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