I need more help.....again

[rj35pj]

Here is a wiring question.....:( I am using a Ron Francis wiring harness, stock cooling fan, standard thermostat switch that screws into the intake, and the AC unit supplied by North Racers. The thermostat switch will turn the radiator cooling fan on at about 185 degrees as it should. I have a fan overide switch wired into the thermo wire (green wire), the overide switch works fine. I wired my AC fan switch into this same wire, this allows all three potential grounds to be run through the fan relay. All three of these methods will turn the cooling fan on. My only problem is that if the thermostat switch has already turned on the cooling fan and I turn on the AC I blow the 20 amp fuse for the heater (that is my power wire for the AC unit). With this info and not being able to see what I am talking about can anyone tell me where I am going wrong? Like I said any one of these three methods work fine except for when I turn on the AC with the cooling fan already running, turned on by engine temperature.
North Racers in their instructions suggest using a Hayden fan control unit and I will be looking into that, I just can't figure out why my idea is not working and I can sure use a fresh set of eyes on this situation......
Thanks,
Bob

[michael everson]

Wow. Never heard of this. You got me stumped. You say all three work fine independently? If so I have no clue. What happens if you turn on th A/C and then ground the fan sensor? Does the fuse blow? All I can think of is that the A/C is actually a positive not a negative
Mike

[Norm B]

What year is your cooling fan from? My 1995 donor had 2 circuits for the fan. One worked from engine temp and the other from the AC. Each would run the fan on low speed individually and when both were energized the fan ran on high speed. Maybe Michael is correct and the AC circuit is positive. I can dig through the wiring diagrams for your year if you want.
Norm

[rj35pj]

I think the AC switch must be positive and is bring in more juice that I don't need.... I did not get a wiring diagram with my AC, I am going to call about that.

[rj35pj]

I spoke with Southern Rods and Parts who supplied the AC unit. The tech guy asked me why I needed a third way to turn on the fan. He said if the thermostat turns the cooling fan on at 185 degrees and I have a manual overide I really don't need a third way to turn on the cooling fan from the AC. He did say that if I did want to wire up a third way I would need a trinary switch instead of the binary switch I am currently using.

[CHAZC5ZX]

that's funny the fan comming on with the A/C is the one you MUST have. If you are running the A/C and come to A stop with no fan the pressure will rise enough to blow the hoses.
Chaz...

[rj35pj]

that's funny the fan comming on with the A/C is the one you MUST have. If you are running the A/C and come to A stop with no fan the pressure will rise enough to blow the hoses.
Chaz...

That is what I questioned...... he felt the fan would come on soon enough to prevent the pressure build up, that is a chance I'm not willing to take. Thank you for confirming what I was thinking.
What have others done in this case????

[loeffler1]

rj35pj

SOUTHERN parts is correct, you need the trinary swith. I've got the same setup with my vintage air unit, enginr block switch, dash override switch and AC switch (trinary). Get online with the vintage air site or call them at (800) 862-6658 and check page 66 of catalog, part nos 24676-VUS (switch kit for barb crimp) or 24678-VUS (switch kit for beadlock crimp) or 11076-VUS (switch kit for female thread). My catalog didn't have the prices in it and I've lost my price sheet. They are great people to work with, probably talk you through your problem. Sounds like you are shorting out something when you double ground the switch and the override.

Bill

[loeffler1]

Looked up the prices for you online. The first two are $51.00 and the third option is $35.50 Mine is the threaded kind that screws into the dryer. The beadlock kind is crimped directly onto the AC line. I'm not sure about the barb crimp. Seems as though any AC shop worth their salt can talk you through this also.

Bill

[xlr8or]

Or get a Lincoln/Taurus two speed fan and combine it with a stand alone harness from The Hollister Road company. That will allow the engine block sensor to turn on the low speed setting and the dash switch and/or AC kick the fan to high.

Much better setup for cooling and making sure the AC condensor gets plenty of airflow when the AC is on.

I run this setup in mine and it works great. All new parts for under $250 and it takes the load off your main harness.

[rj35pj]

Thanks for all the help and suggestions. Before I read the last few posts I ordered the unit below from Yogi's Inc a streetrod parts supplier. When I read the discription it was what I was looking for. If this doesn't work I will certainly follow up with Vintage Air.
Thanks again!
RELAY - AIR CONDITIONING
From Flex-A-Lite Fans


Taps into A/C hot lead. Automatically engages fan when air conditioner is turned on, gives your system a head start on the added cooling demand (not required on Flex-a-Lite fans with built-in A/C relays)










#FLE31146



RELAY - AIR CONDITIONING / EA







Quantity:
Only $18.50

[tirod]

Some factory wiring setups use a diode in the system to prevent back feeding the AC circuit when both are on.

[rj35pj]

Some factory wiring setups use a diode in the system to prevent back feeding the AC circuit when both are on.

That diode set up would have been nice, but this is just one more example of why calling these cars "kit cars" is misleading. I've told people I used to think you just put part "A" together with part "B" and that was all there was to it.......not so. :)

[CJBergquist]

I have the RF harness and the North Racers AC and didn't need anything special. I have an on/off switch that powers a remote relay. I have a thermostat switch that closes to ground at 180 degrees. I wired this to a second relay. The primary side of the second relay is connected to hot source and the thermostat switch completes the circuit to ground when the temp reaches 180 degrees. The secondary side of this relay powers the first relay, turning the fan on. The wire from the AC dryer also is wired to the first relay.

So, I can turn on the fan with the on/off switch...or if the temp reaches 180 degrees the thermostat will turn on the fan...and last but not least if I turn on the AC the fan will be turned on.

I think I have a hand drawn wiring diagram. If you would like to see it I guess I could take a photo and post here. Let me know. HTH

[rj35pj]

I have the RF harness and the North Racers AC and didn't need anything special. I have an on/off switch that powers a remote relay. I have a thermostat switch that closes to ground at 180 degrees. I wired this to a second relay. The primary side of the second relay is connected to hot source and the thermostat switch completes the circuit to ground when the temp reaches 180 degrees. The secondary side of this relay powers the first relay, turning the fan on. The wire from the AC dryer also is wired to the first relay.

So, I can turn on the fan with the on/off switch...or if the temp reaches 180 degrees the thermostat will turn on the fan...and last but not least if I turn on the AC the fan will be turned on.

I think I have a hand drawn wiring diagram. If you would like to see it I guess I could take a photo and post here. Let me know. HTH

Chris,
Thank you for your offer. I finally did sort out my problem and now like you I have three different ways of turning on the cooloing fan. :)

[Thanatopsis]

Chris,
Thank you for your offer. I finally did sort out my problem and now like you I have three different ways of turning on the cooloing fan. :)

What was your final solution?

[rj35pj]

What was your final solution?

The three ways are grounding the fan circuit through the thermostat, grounding the circuit with a manual override switch, and the one that gave me the tough time was running a relay with a resistor with one wire going to the grounding wire from the thermostat, one wire from the AC switch (runs from switch to compressor) and two other grounds. After all this I found out that Ron Francis makes a relay for this exact problem with the wires already color coded to fit the harness that came with my kit. Live and learn.
In the course of learning I did short out two thermostats-that cost me a few bucks.