Need to add a fan for better radiator cooling (Page 1/1)
n7vrz SEP 19, 11:50 AM
'95 GMC Sonoma 4 cyl auto a/c
With a/c running and truck at a stop the thing wants to overheat. Not so running down the highway. I've checked the radiator and it isn't plugged or corroded. Engine mounted fan seems to be working also. Shroud is in place.
So I want to add a fan to kick in when I switch on the a/c.
My question is where would I hook up the wire to trip the relay? Should I splice it in to the compressor clutch wire or somewhere else? I would think that it would be 'somewhere else' since the clutch would cycle as a/c is needed or not due to interior temp. I wouldn't want the fan to cycle too.
jaskispyder SEP 19, 02:14 PM
Hmm, this probably has temp. controlled clutch on the fan (engine mounted). It could be bad.

http://www.autopartswarehou...8v9e2a6-apwidg9S8GqP

What is the coolant mixture? 50/50?

Otherwise, you would have to find the wire that controls the AC compressor, tap into that, run a relay to the new rad. mounted fan unit.

I think it would be easier to fix the system you have though.

My truck, with a 350 engine and A/C doesn't overheat, even on the hottest day (95F) when it sitting at idle, with the A/C on. The fan is mounted to the engine.

[This message has been edited by jaskispyder (edited 09-19-2012).]

Stubby79 SEP 19, 02:25 PM
You could find a wire that's always hot(or grounded) at the switch when it's turned on. There ought to be one.
Or else you could hook it into the brake switch, so it's only on when you're pressing the brake...then it'd be on the entire time you're stuck in traffic and not when you're driving.
'course I agree with the previous post: something ain't quite right with your cooling system or fan.

BTW, are you basing this off your temp gauge or is it boiling over? Temp sensor for the gauge is usually right at the outlet to the rad, so it's going to read a lot higher at idle with only the air flow from the fan than it would while moving. If it's going into the red though, yah, something isn't right.

[This message has been edited by Stubby79 (edited 09-19-2012).]

carnut122 SEP 19, 09:01 PM
There should be a "hot" wire that runs from the back of the AC switch on your dash. It will only be hot when you want air. Use it as your "control" input for your fan relay.
n7vrz SEP 19, 09:53 PM
stubby, I'm basing the temp on the gage trying to peg high when the a/c is on and the car isn't moving or is going very slow. Get up to highway speed (or turn the a/c off) and the temp comes back down.

carnut, thanks. I'll find that wire.

jaskispyder, I forgot about the fan clutch. I'll replace it first then go with an add on fan if it still wants of over heat.

[This message has been edited by n7vrz (edited 09-19-2012).]

jaskispyder SEP 20, 12:08 PM
hoses could be bad also... something to look at.
rogergarrison SEP 20, 07:01 PM
Flex A Lite makes a self contained switch ($30 for kit) that shuts the fans off and on at whatever temp you dial. I put one on my Mercedes. I wouldnt connect it to the air compressor clutch wire. At least on mine, it blew the fuse everytime.

Truthfully though, check to see if your original electric fan runs hot wired. If it does, check to see if the sensor switch is powering it on. Id rather try to fix the OEM system first.

[This message has been edited by rogergarrison (edited 09-20-2012).]

jaskispyder SEP 21, 08:35 AM

quote
Originally posted by rogergarrison:

Flex A Lite makes a self contained switch ($30 for kit) that shuts the fans off and on at whatever temp you dial. I put one on my Mercedes. I wouldnt connect it to the air compressor clutch wire. At least on mine, it blew the fuse everytime.

Truthfully though, check to see if your original electric fan runs hot wired. If it does, check to see if the sensor switch is powering it on. Id rather try to fix the OEM system first.



A couple of things...

He doesn't have an electric fan, it is run off the engine, by a belt.

Also, I would recommend running a relay from the compressor switch, not wired directly to the switch (as that would draw too many amps for the circuit). (maybe you did this, but it wasn't clear in your text).
n7vrz SEP 25, 04:06 PM
Seems to have been the fan clutch. Replaced it with a new one and could now hear the fan. Couldn't hear it before.
Remarkable how the mind accommodates the slow change in sound to be the new norm. Then suddenly when it is really normal it hears it anew.
Anyway, thanks for reminding me about the fan clutch.
jaskispyder SEP 26, 09:12 AM

quote
Originally posted by n7vrz:

Seems to have been the fan clutch. Replaced it with a new one and could now hear the fan. Couldn't hear it before.
Remarkable how the mind accommodates the slow change in sound to be the new norm. Then suddenly when it is really normal it hears it anew.
Anyway, thanks for reminding me about the fan clutch.



excellent!