radiator fan always on (Page 1/1)
freek JUN 14, 03:21 PM
I just got my 1987 Fiero GT v6 from the USA. Very good car, low mileage. I have got a question about the radiator fan, 1 speed. With the contact in on position, the fan runs continuosly, even with cold and non running engine and AC in off position. I checked the fan switch and fan relay, both in good order. Disconneted the wiring to the AC control unit in the dash, no effect. What else can cause the fan running? The AC high pressure switch ? where is it located so I can disconnect. The fan only stops when I disconnect the relay,
The other problem is the AC, it works, but at idle (and higher revs) the compressor kicks in and out every 5 secs (you can hear the magnetic coupling ticking). What could be the error, maybe it is linked to the fan error since I noticed in the electical schematic that the AC system and radiator fan loops are connected.
Freek, the Netherlands (Eu)
Patrick JUN 14, 04:11 PM

quote
Originally posted by freek:

I have got a question about the radiator fan, 1 speed. With the contact in on position, the fan runs continuosly, even with cold and non running engine and AC in off position. I checked the fan switch and fan relay, both in good order. Disconneted the wiring to the AC control unit in the dash, no effect. What else can cause the fan running? The AC high pressure switch ? where is it located so I can disconnect. The fan only stops when I disconnect the relay.



It's possible someone has either permanently grounded the circuit, or has installed a switch to ground. Ask the previous owner if you can.


quote
Originally posted by freek:

The other problem is the AC, it works, but at idle (and higher revs) the compressor kicks in and out every 5 secs (you can hear the magnetic coupling ticking). What could be the error...



Could just be low on refrigerant and in need a recharge.
freek JUN 14, 04:55 PM
I do not know the last owner, and could not find any self mounted manual switch or jumper to ground. It is a car from sunny Florida, so you can be right the previous owner made a switch or something. Because I can not find it, I Have disconnected all original switches (triel and error method) to ground except the AC high press switch. I just learned that this switch is on the AC compressor, will try to disconnect and see what happens. If this does not work I guess I have to run a new wire from relay to the fan switch.
I will have the AC system recharged, good idea.
FX JUN 14, 05:51 PM
You could have a bad heat sensor that's screwed into the engine just to the right side of the thermostat housing tube that turns the fan on when hot, or a short in that wire. Try unplugging that heat sensor single wire and see if that stops the fan from running, if so, bad sensor, or short in that wire somewhere...And yes, a/c could just be low on freon...

[This message has been edited by FX (edited 06-14-2019).]

theogre JUN 14, 11:29 PM
or fan relay contact is stuck close/on.
or some fool bypass the relay. I've seen this on many cars not just Fiero.

Fan control green wire is grounded/earthed for any reason Turns On that relay. Try pulling E Fan fuse to see relay then turns off the fan.
See my Cave, Rad Fan

Fan Relay is in Front of Left HL assembly.
To get move access...
See my Cave, Headlights section "Is there an easier way to change Fiero headlights?" Just flip the HL should help.


------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 06-14-2019).]

freek JUN 15, 04:19 AM
thank you guys, your input is appreciated, will do some investigation next week.....very happy with the car though! pretty rare here in Holland, all standard but great sound !!
fierofool JUN 15, 09:21 AM
If the AC compressor has been replaced, it's possible that it has the new style pressure switches installed. A common problem when using the two wire pressure switches is that the radiator fan runs constantly. Check the end of the compressor to determine if the switches are still single wire or double wire.
freek JUN 23, 05:29 AM
done some investigations. I learned that I have the HR6 compressor with 2 wired switches. I can see that this was not mounted originally, the switches are wired to ground externally. When I disconnect the grey switch (connected to the green/white wire) the fan stops, as it should, while AC in off mode and engine cold. Checked the switch; it is normally closed and should be normally open, so I presume I have a bad AC low pressure/fan control switch and have found the problem with the fan !!.
I also checked the blue switch, it is also normally closed so that is oke. However, switches seem to be mounted in the wrong way compared with pictures I found, do not know if this matters: looking at the back of the compressor with the 2 piping connections on top, the blue switch is bottom left and grey swicht is bottm right.
Any comments guys? Thanks , Freek