Fan Stays on (Page 1/2)
Spadesluck MAY 03, 06:48 PM
I have an 87 GT. Wasn't until recently the fan just stays on with the key in the on position. Things I have checked:

Relay...tested it with a power supply and it does is job in clicking on and off
Sensor....I disconnected the sensor and the fan stays on

I can only assume that I have a grounded wire some where then? Is there any fuse associated with the fan electronics? Ideas?
Patrick MAY 03, 09:41 PM

Turn off the A/C.
Spadesluck MAY 03, 11:47 PM

quote
Originally posted by Patrick:


Turn off the A/C.



It is off.
cliffw MAY 04, 02:56 AM
There is a reason I offer no help here in Tech. I know nothing compared to the many tech gurus.

There has to be a fuse but, what would that matter ? If it's blown, the fan won't work. Testing purposes ?

I have the opposite problem. Mine won't come on, unless the A/C is on. Where is the relay ? The sensor ?
Spadesluck MAY 04, 03:02 AM

quote
Originally posted by cliffw:

There is a reason I offer no help here in Tech. I know nothing compared to the many tech gurus.

There has to be a fuse but, what would that matter ? If it's blown, the fan won't work. Testing purposes ?

I have the opposite problem. Mine won't come on, unless the A/C is on. Where is the relay ? The sensor ?



Relay is in front of the driver side headlight. Sensor is a one wire plug next to the thermostat on the motor. Yours sounds like a fan sensor is bad.

I asked for a fuse to make sure I do not have a short in there.

[This message has been edited by Spadesluck (edited 05-04-2019).]

Blacktree MAY 04, 10:25 AM
To Spadesluck, I'm assuming you tested the relay with the engine off? If the engine is on, and the fan is running, the relay shouldn't be clicking on and off (it should be constantly on). So I'm assuming something is holding the relay on whenever the ignition is hot. If that's the case, then you probably have a short to ground in the green&white wire that activates the relay. That wire runs to a lot of places (like the fan switch, the A/C compressor, and the HVAC panel). But you could start by unplugging those things one by one, and see if anything changes.

To CliffW, I'm guessing a bad relay. Like mentioned above, it's under the driver side headlight. You can test the relay using a paperclip, or a short piece of wire, as a jumper. With the ignition on, back-probe the green&white wire, and touch the other end of your jumper to a chassis ground. The relay should click (and the fan should come on). If it doesn't, the relay is probably toast. If it does, then the fan switch is probably toast. If you end up replacing the fan switch, I would suggest getting a 210°F fan switch from Rodney Dickman. ---> http://rodneydickman.com/ca...th=22&products_id=88
Spadesluck MAY 04, 03:17 PM
Found my problem. One of the pressure switches on my AC Compressor is triggering the fan on all the time with the key in run. I check this by unplugging all the sensors one at a time and leaving them unplugged. Figured I would pass this along.
Blacktree MAY 04, 04:14 PM
The good news is, even with the wire unplugged from the A/C compressor, the HVAC panel will still turn on the fan. However, replacing the fan switch on the compressor will require evacuating the refrigerant.
Spadesluck MAY 04, 04:34 PM

quote
Originally posted by Blacktree:

The good news is, even with the wire unplugged from the A/C compressor, the HVAC panel will still turn on the fan. However, replacing the fan switch on the compressor will require evacuating the refrigerant.



Which is why I am just going to leave it alone right now.
cliffw MAY 04, 07:57 PM

quote
Originally posted by Spadesluck:
Relay is in front of the driver side headlight. Sensor is a one wire plug next to the thermostat on the motor. Yours sounds like a fan sensor is bad.



Thank you. Thank you.


quote
Originally posted by Spadesluck:
I asked for a fuse to make sure I do not have a short in there.



In where ? Am I missing something ?
12v go into the fuse and comes out the other side. A short would blow the fuse. Then it would't run at all.
Am I missing something ?

Do you have a test light ? An ohm meter ? You can make a test light from a Fiero side marker lamp.

[/QUOTE]

You don't have a short. You have something energizing the fan.