Hot Wired Radator Fan (Page 2/2)
theogre AUG 23, 09:47 AM

quote
Originally posted by MasterBaker:
The former owner told me car didn’t not overheat but was worried fan did run much and temp were up over 200 degrees. He told the mechanic the sensor may be bad. Mechanic totally rigged it.

Question on the AC switch that turns on radiator fan. If the system is low on Freon will that disable the switch when you turn on AC inside car. Car does not blow cold air at all. It’s very low on Freon. Didn’t know if that switch also relies on gas pressure inside AC system to trigger fan.

1st problem is Engine is Not "Running Hot" running @ 200-230°F = The PO had no clue and "mechanic" is ripoff shop.

AC Limit switches Will Not disable the Rad Fan.
Low switch can stay on w/ low pressure so compressor does little but when any are "off" then ECM says No AC and won't run the AC Clutch.
fierosound AUG 23, 10:20 AM
As you can see, the fan temp switch closes at 235F, opens at 225F.
So technically not over heating as it's designed that way, but starts getting close to the "red" on the gauge.
At my altitude (3500 ft) the engine sure didn't like it before the fan kicked in.

Many have changed out the switch to one the has lower temp on/off cycles to keep the engine more consistent with the 195F thermostat.
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[This message has been edited by fierosound (edited 08-23-2023).]

MasterBaker AUG 23, 10:48 AM

quote
Originally posted by theogre:

[QUOTE]Originally posted by MasterBaker:
The former owner told me car didn’t not overheat but was worried fan did run much and temp were up over 200 degrees. He told the mechanic the sensor may be bad. Mechanic totally rigged it.

Question on the AC switch that turns on radiator fan. If the system is low on Freon will that disable the switch when you turn on AC inside car. Car does not blow cold air at all. It’s very low on Freon. Didn’t know if that switch also relies on gas pressure inside AC system to trigger fan.

1st problem is Engine is Not "Running Hot" running @ 200-230°F = The PO had no clue and "mechanic" is ripoff shop.

AC Limit switches Will Not disable the Rad Fan.
Low switch can stay on w/ low pressure so compressor does little but when any are "off" then ECM says No AC and won't run the AC Clutch.[/QUOTE]

I spoke with the former owner of the car. He is beyond pissed the mechanic hotwired the fan and didn't address his concerns. Especially when he didn't necessary have an overheating issue. Car came from PA. Fan likely wouldn't of kicked on much up there. Plus he lived in the country side, no stop and go, all highway miles. Think he saw some higher temps on the gage and told the mechanic to change temp sensor or radiator temp fan sensor. The mechanic just rigged the damn thing for pennies on the dollar. He never addressed any of the issues or concerns. I am working on getting it reworked back to factory. I am going to replace both sensors to make sure temp is accurate and to make sure fan kicks on at the correct temp too.
Vintage-Nut AUG 23, 10:57 AM
BTW

In 2003, I heard that my '88 GT Radiator Fan was "On" on a cold start with the A/C control "Off".

As the factory A/C stopped working (no cold air) and the compressor belt was removed years ago; I found that the A/C High Pressure Switch had shorted to ground causing the fan to run constantly.

By disconnect the A/C High Pressure Switch from the Compressor, the problem was solved, and the fan switch and the fan have been working properly after the event.

[This message has been edited by Vintage-Nut (edited 08-23-2023).]

Fieros4evr AUG 23, 12:57 PM
Similar situation on my bucket list to repair: A month ago, I brought an 87 Fiero 2.5 with an overheating issue right after start, requiring the ac switch to be on in order to run the fan to avoid overheating. I showed theogre back then a photo of a cluster wire with 3 plugs sitting unconnected in the engine bay and he identified them connectors to the ac compressor. The funny thing is that this Fiero did not have a compressor at all connected to the engine, just a spool of some sort in its place running with the timing belt.

I don’t want to interrupt MasterBaker’s post, but I mentioned this if it by chance relates altogether with overheating. Thanks MasterBaker for this important topic and to everyone involved.

[This message has been edited by Fieros4evr (edited 08-23-2023).]

MasterBaker AUG 23, 02:19 PM

quote
Originally posted by Vintage-Nut:

BTW

In 2003, I heard that my '88 GT Radiator Fan was "On" on a cold start with the A/C control "Off".

As the factory A/C stopped working (no cold air) and the compressor belt was removed years ago; I found that the A/C High Pressure Switch had shorted to ground causing the fan to run constantly.

By disconnect the A/C High Pressure Switch from the Compressor, the problem was solved, and the fan switch and the fan have been working properly after the event.




Going to splice the radiator fan wire back to factory this weekend. I am very interested to see if the A/C high pressure switch is functioning with low pressure/Freon in system. Thanks to the forum members I will be able to trouble shot the current issue and now know that the A/C pressure switch can defaulted to ground. I would have never thought about looking at that switch had it not been for the members commenting in the thread. No I know it can be unplugged to allow the fan to operate from the fan temp sensor. Great stuff! Thanks all.

[This message has been edited by MasterBaker (edited 08-23-2023).]

theogre AUG 23, 07:37 PM
If splicing wires up front etc...
Use "Weather Proof" crimps preferred 3M ones and good crimper. Crap crimpers often cut the heat shrink tube trying to crush the metal part.
Then shrink the tube to melt the "glue" to seal it.

Clean the wire(s) plastic before crimping so "glue" works better.

[This message has been edited by theogre (edited 08-23-2023).]