Stock fan amp draw

[str8stang036]

I am using my stock fan with a manual switch for high speed. Ever since I connected the fan it has a big amp draw, it drops close to 2 volts as long as it's on. The alternator does help out however I wanted to know if it's supposed to be such a big drop?

Also, The fan started heating up the wires connected to the switch so much, that it ended up ruining the switch. What would cause this? My dad and I are stumped at this. Is this a tell tale sign the fan is going out of business?

 

[str8stang036]

How do I know if both low and high speed are on at the same time?

 

[SQUEEZE&STROKE]

There are two seperate wires that need to be GROUNDED inorder to turn each fan on...one wire for low, one for high. This is if you pulled the pin in the computer connector. When I converted my car to an A9L I just ran the two wires to two switches...but no power needs to go to it, just ground the wires.

 

[desertcox05]

you have 3 wires going to the motor right 1 for low speed 1 for high speed and one for the ground. don't ask me what the colors are. like you said the motor could be going out too. as for burning up the switch, it can't handle the amp draw which is why stock goes through the ccrm. you may have to wire it through a relay but I'm betting on the motor going bad . one more thing both speeds can't be on at the same time

 

[SQUEEZE&STROKE]

you have 3 wires going to the motor right 1 for low speed 1 for high speed and one for the ground don't ask me what the colors are. like you said the motor could be going out too. as for burning up the switch it can't handle the amp draw which is why stock goes through the ccrm you may have to wire it through a relay but I'm betting on the motor going bad

Correct:

Orange-High Speed
Red-Low Speed
Black-Ground


I am talking about using the wires inside the cabin from the computer 52 pin connector. This way you use the CCRM and dont have high voltage High amperage wires running all over.

FWIW-Now that my car is carbed I have a 50 or 60 amp relay and cable the size of my pinky to run the power to the fan. I also have a 50 or 60 amp fuse tied in as well. I tried it with smaller wire and it melted in about 60 seconds of fan use.

 

[HISSIN50]

The OEM fan control is interesting in that the default is for low to be on. EEC intervention is required to turn it off.

You're smart to question if both speeds are on at once. If you're above ~208*F, low should be on. If so, manually turning on high isnt a good idea.

There should not be that large a hit to the system unless you dropped a diode in the alternator. Keep an eye on your fan wiring and connector in case the fan motor is starting to seize (causing a large draw).

Here's a little write-up on installing manual fan switches.

Good luck.

 

[m0l0]

The OEM fan control is interesting in that the default is for low to be on. EEC intervention is required to turn it off.

Thats right this is a fail safe addon , for whatever reason te computer or any system involved fails, the computer enters limp mode this will get you to the next service shop.

 

[str8stang036]

Is it better to use the low speed fan on constantly as opposed to the high speed fan?

I no longer have the stock connector to the fan, it was removed. How would I connect the fan to the ccrm then? I have an idea, however I want to hear other options.

 

[str8stang036]

ttt

 

[HISSIN50]

Is it better to use the low speed fan on constantly as opposed to the high speed fan?

I no longer have the stock connector to the fan, it was removed. How would I connect the fan to the ccrm then? I have an idea, however I want to hear other options.

Low potentially might not be enough but it is easier on the fan and electrical system to only use low.

For the connection, you can get a new connector from Resto houses. Or solder spade terminals to the OEM wires. You have to be sure the terminals fit really tight, otherwise loose connections cause poor conductivity, which causes heat, which causes failure.

Good luck.

 

[str8stang036]

What if I made the fan have its own circuit? I saw somethings on jegs for similar use, however they used a 30amp 4-pin relay. What amperage relay should I use to make a circuit like this?

 

[HISSIN50]

What if I made the fan have its own circuit? I saw somethings on jegs for similar use, however they used a 30amp 4-pin relay. What amperage relay should I use to make a circuit like this?

You'd be giving up your OEM two-speed fan control though.

Does your fan create that huge drop in voltage even when the car is cold?
If not, you can work around the existing issue.

If it does, something is probably amiss and you can do a work-around like you're considering.

You can use some prefabbed controller or relay if you want. Or just wire up your own relay circuit. You can use the OEM inputs to trigger the relay you add if you want. That's how I'd wire it (I'd do it so the relay is triggered if the car reaches low speed on temps [208 unless you can tune it down] and/or it comes on with the AC).

If you want the best tractability, use a 75 amp Bosch relay. Otherwise a 40 amp relay should get you by but the load from the fan will shorten the longevity of the relay. Keep spares in your glovebox.


More involved: To use two speeds, you really need 3 relays (a control relay and two drivers).

Lastly, the absolute best way to do it is with a Delta Controller ( www.DcControl.com ). This is a complete package that makes anything else look like a chisel compared to a CNC machine.

Good luck.

 

[str8stang036]

I would love to try the oem way. I don't care much for switching b/w low and high speed. I removed the connector and wires going to ccrm from fan. I can get to the 14 and 17 pins on the ccrm for low and high, but I don't know which wires went to which numbers on the ccrm from the fan to get it going. From looking at mustang-tech, I believe it is pin 6 and 7 that help with that and they are missing because I removed them. I would much rather solve this problem using the oem or similar electrical route.

 

[HISSIN50]

If you dont care about high or low and just want high to work:

Grab a SPST or SPDT relay (or preferably a 75 amp relay. They're about 25 bucks but you can find them in some Mark VIII's at the J/Y).

30 is fused battery power.
87 goes to the fan's high speed terminal
85 is grounded.
86 will have a couple legs. One will connect to CCRM Pin 14 (so you're using low speed to drive the high speed fan now). The other leg will connect to the HVAC feed into the LPCS.

NOTE: You must use blocking diodes on the two legs for 86 to prevent backfeed. They're about 50 cents a piece at Radio Shack.

Now when you reach 208*F or the AC is on, high speed will come on.

 

[maximos]

My fan went bad a few days ago and I went ahead and replaced it with a Mishimoto fan (and radiator since I was in there already). The problem I am now faced with is that the Mishimoto fan only has two wires coming from the motor (ground wire and a fan-on wire). As you guys know already there are three wires leading into the factory fan (ground wire, low-fan, high-fan). What would you recommend I do to get the fan to come on and stay on when the temperature reaches the appropriate level? Also, are there any other fans you woud recommend because I am definitely open to other options.

 

[HISSIN50]

My fan went bad a few days ago and I went ahead and replaced it with a Mishimoto fan (and radiator since I was in there already). The problem I am now faced with is that the Mishimoto fan only has two wires coming from the motor (ground wire and a fan-on wire). As you guys know already there are three wires leading into the factory fan (ground wire, low-fan, high-fan). What would you recommend I do to get the fan to come on and stay on when the temperature reaches the appropriate level? Also, are there any other fans you woud recommend because I am definitely open to other options.

The following would work for your application since both had a one-speed fan in mind.

If you dont care about high or low and just want high to work:

Grab a SPST or SPDT relay (or preferably a 75 amp relay. They're about 25 bucks but you can find them in some Mark VIII's at the J/Y).

30 is fused battery power.
87 goes to the fan's high speed terminal
85 is grounded.
86 will have a couple legs. One will connect to CCRM Pin 14 (so you're using low speed to drive the high speed fan now). The other leg will connect to the HVAC feed into the LPCS.

NOTE: You must use blocking diodes on the two legs for 86 to prevent backfeed. They're about 50 cents a piece at Radio Shack.

Now when you reach 208*F or the AC is on, high speed will come on.

You could replace your OEM fan motor with one from AZ (they're about 60 bucks with lifetime warranty). Otherwise, some fabbing is required. It's too bad that Viper fans got so expensive because they are neat if you're in a real hot climate.

If your OEM fan control still works, you can actually add one relay with the inputs being the OEM fan plug to trigger a relay. Again, use blocking diodes with low and high speed terminals connected to pin 86 of a relay. That way anytime your OEM fan would have been on, your new fan will be on.

 

[str8stang036]

thanks for the replies everyone. I am going to look for the relay today and have my more electrically savvy friend help me tomorrow.

What store can I find the 75 amp relay at? The highest I have seen is 40amp at radioshack.

 

[maximos]

I fixed it without all of the technical wiring. I simply bought a Dorman OE replacement fan and it works great. It wasn't too expensive either. Fast install too!

 

[HISSIN50]

What store can I find the 75 amp relay at? The highest I have seen is 40amp at radioshack.

You generally have to buy them online.

For now a 40 amp relay should work fine but at some point you'll want to upgrade (before the 40 amper takes a dump).

 

[str8stang036]

For future reference, how can I tell the fan may be at the end of its duty, other than high amp draw? What is there to check?