Variable load control module - vlcm fan relay

mlschultz

Boost King
Well, I think it is The Mark's turn to experience a flaky VLCM. This all started this past Friday, when I took it to get the annual emission test.

Car ran normal up to operating temp 174* ( I have a Riesche 170* T-stat) with the a/c on before plugging into the OBD reader at the test facility. After the test on the way home, it ran up to 230*, and the main radiator cooling fan was not running (The fan is a OEM Ford Mustang fan). The two auxiliary Spal fans I had installed were running though.

Yesterday, I started the car cold, turned the a/c on max, and the fan turned on as it should. I drove it to the car show and everything was fine. Drove it home, and it did the same thing again and the main fan turned off.

I checked for loose connections, and everything looked fine to me. Just cold started the car now, turned max a/c on, and again, everything worked as it should. I turned a/c off, and after a minute the main fan turned off. Spal fans are wired to run at 174* regardless of a/c position. Temp got to 174, and main fan turned back on with Spal fans. I turned a/c to max and set at 68*. Everything worked fine. Here's the kicker - Cabin got to 68* and the vent output slowed down as it should. I look at the radiator fan and it turned off. The Spal fans were still running. From that point on, the main radiator fan will not turn on regardless of what I do. I am letting the car cool down now, and will see if the main fan will turn on.

I bought a VLCM on ebay last night, but I have a feeling there might be something else going on here.

After the cool down, started up and switched max a/c on, and the main fan came on again. I turned it off, and after a minute, the main fan turned off as it should. Reached 174*, and main fan turned back on. This time, I left a/c off to see if it was related to the a/c function or not. After about 5 minutes, the main fan turned off. Temp started to climb, yet the main fan would not turn back on. A/C was left off the entire time.

I am calling Aric next Tuesday to set up an appointment for him to chase it down.
 
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Mad1stGen

Booster
Unplug the temp sensor on the crossover tube while the car is running. Does the fan turn on couple seconds later ?
 

mlschultz

Boost King
Yes, All three fans turn on when the temp sensor is unplugged at cold start. I did not run it up to 174 though, to see if they would remain on.

With that said, I suspect I possibly have either a bad main fan or ground.
 

Mad1stGen

Booster
Yes, All three fans turn on when the temp sensor is unplugged at cold start. I did not run it up to 174 though, to see if they would remain on.

With that said, I suspect I possibly have either a bad main fan or ground.
Do it at full temp, when you can't get the main fan to turn back on no matter what. That should rule out relays in the VLCM.
 

mlschultz

Boost King
I unplugged the temp sensor and ran the car until the main fan cut off. Plugged the temp sensor back in, and the temp was at 140*. Spal fans kept running.
 

Mad1stGen

Booster
I unplugged the temp sensor and ran the car until the main fan cut off. Plugged the temp sensor back in, and the temp was at 140*. Spal fans kept running.
I believe that with the sensor unplugged the main fan should never turn off. Hmm ... Is there another sensor where the SPAL fans get their signal ?
 

mlschultz

Boost King
I believe that with the sensor unplugged the main fan should never turn off. Hmm ... Is there another sensor where the SPAL fans get their signal ?

I stated that incorrectly. SPAL fans did not run when the temp was below 174* with the temp sensor plugged in. They did run when the temp sensor was unplugged with temp at 140*. I do not know what or where Aric tapped into to control the SPAL fans, but there is no stand alone aftermarket controller for the SPAL fans that I know of.
 

Mad1stGen

Booster
It sounds like there is a relay (I would hope there is lol) that's triggered by either the VLCM output or the temp sensor itself. So it sounds like the SPAL fans are operating correctly, while the OEM fan is not.

I think you're on the right track that the OEM fan is iffy (either the motor, the plug, or the grounding). I know you're not running the original M8 fan anymore, and the GT fan is newer, but it's a mustang fan after all :roll_over:

Do the original fan wires from the car's harness go directly to the motor, or is there a thermostat (found on cobra/gt fan) shroud in line ?
 

mlschultz

Boost King
I spoke with Aric, and will be taking the car to him this Thursday.

Jeremi, There is a relay and fuse for the SPAL fans. They tapped into the battery for power, and the relay and fuse are just off the battery.

I just followed the OEM two wires from the main fan towards the passenger fender where it connects into a larger harness. I did see where they spliced into the main fan wires under the Vortech to use as a trigger for the SPAL fans. No t-stat found in line from the plug to the main harness. Just two wires wrapped up in OEM plastic covering and tape.

If that is the case, I think it is safe to say the Mustang fan is a gonner. The Mustang fan was put in the car August, 2011.

Do you think I can fit the Ford Racing fan - 2005-2013 MUSTANG PERFORMANCE COOLING FAN M-8C607-MSVT in the car? The one in it now is 3R33-8C607-AA.
 

driller

El Presidente
Interesting... the cooling fan in the Blue Flame has exhibited similar difficulties. I haven't had time to look into it in any detail yet but I did run a hot wire to the fan temporarily to be able to run the fan when needed so I don't believe the ground is a problem. :confused:
 

Mad1stGen

Booster
Mike, I think the 05 and up radiators are much larger, so the fan is probably larger as well. I have no experience with them, sorry.

Waiting to hear Arics findings though. FYI you can swap the OEM Mark VIII fan motor onto the mustang shroud if you wanted that option.
 

mlschultz

Boost King
Just got back from leaving The Mark with Aric. I gave him my spiel, thinking it might save him some time in the diag. He said he is going to start from scratch and hunt it down. I told him if it ends up being a dead main fan, I want to go with a 2-3k CFM 16" SPAL fan instead of another SN95 4.6 fan. He said they are noisy. I said I will keep the windows up if need be. I am so done screwing around with fans lol :)
 

mlschultz

Boost King
Already got a phone call. They have been trying to get the main fan to fail for an hour now, and the main fan keeps running fine. lol This cool weather air we are having today must be just cool enough to keep it from failing. Never fails... Nothing is easy with The Mark... lol.
 

mlschultz

Boost King
Aric called and said the car sat in the corner of the shop and ran most of the day with no problem. The main fan would not fail.
I wonder now if the emission test did something to the car, and if plugging in with whatever diag tool Aric has undid or fixed something in the PCM. I dunno.

The plan is - they are going to take it home and drive it more tonight, and try again tomorrow to try and get the main fan to fail. Back to more normal Atlanta summer weather tomorrow. That should help heat things up.
 

mlschultz

Boost King
Going to pick The Mark up at Aric's. He ran the gas tank empty, put more gas in it, and still runs fine.

All I can say is, I guess the monster needed some bonding time with it's maker... :confused:
 

mlschultz

Boost King
Interesting... the cooling fan in the Blue Flame has exhibited similar difficulties. I haven't had time to look into it in any detail yet but I did run a hot wire to the fan temporarily to be able to run the fan when needed so I don't believe the ground is a problem. :confused:
Good luck JP, and I hope you can figure it out. I have a couple VLCM's if you want to try them.

The Mark is back in the cave under cover after I de-funked it inside and out of shop crud. They ran it for 6 hours in the shop with a/c on & off and it ran 174-176* the entire time. So the story goes... to be continued...
 

mlschultz

Boost King
Update - Went to a cruise-in yesterday, and all was fine. Came home, and I noticed the engine temp on the OBDII dash reader was higher than it should be for the IAT being displayed. It was a cool day for around here, and the car should not be running in the 200's.

I shine a flashlight at the main fan, and sure enough, the SPAL fans were running, but the main fan was not. :wave:

So I poke the flashlight at the connector plug for the main fan while the engine is running, and the main fan turns on. I poke at it again, and the fan turns off. lol problem solved :thumbsup:. I have no idea why I didn't try this before. I checked the connection before, and it was fine.

Here's a couple photo's of the connector. 1998 must be a bad year for Mark fan connectors lol. I have the same issue with the cabin fan motor.






 
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