: Fun with aux fans (limo related)

08-17-11, 12:34 PM
So here's what I've got:


It was a really ingenious arrangement that I may try to duplicate. They used a combination of an electronic fan controller (which is dead and gone) and 2 relays to control 2 auxiliary fans (also dead). The fan controller looked like it was purely a thermal switch. It had 5 seperate terminals on it, but after examining the wiring I think it was really just a thermal switch for dual fans.

The coach builder had it set up so that the fans would come on under one of 3 circumstances:
1) Manual switch on the dash
2) Thermal fan controller (had a radiator probe)
3) A/C high pressure switch

One of the relays had inputs for both the manual switch and the A/C pressure switch. The other relay had an input for the thermal switch. They were wired to each other so any of the 3 events would trigger the fans. It looks complicated at first, but after staring at it for 3 or 4 hours I figured it out.

Both aux fans are inoperative. One is seized up and the other is just not working. I ordered up one from Jeg's to see how it goes. While I'm waiting for it to arrive, I need draw a picture (so I don't forget what all the wires are for) and tape it back up.

08-17-11, 10:52 PM
Okay. My '96's A/C got warm at idle. It was really only effective when I was moving. It drove me nuts. This '94 has a different cooling fan arrangement, plus an extra fan on the stock A/C condenser. There are 4 fans in all.

I like to think the coach builder designed things the way they did for a reason. I ordered up all the parts from Jeg's to reconstruct that arrangement. Relays, harness, wiring, 2 fans and a thermal control. It should work exactly like they had intended, and hopefully keep the A/C cold even at idle. The stock primary fan drops the A/C pressures immediately, but allows them to creep back up to 225 psi so before it kicks in again. I'm thinking having the 2 aux fans working properly should keep the pressure more consistent and lower (which means cooler).

I took enough pics that I should be able to use the Jeg's dual fan harness to rebuild the original setup.

In the meantime, I need to add more refrigerant to the system. It's cool, but not cold.

And the lack of air out of the front vents is driving me insane. I'm going to get to the bottom of it tomorrow. I'm thinking big rodent's nest blocking it up. The fan is working as it should. Not enough air is coming out.

08-18-11, 03:48 AM
Is there a switch panel in place of the left center dash vent on this limo? Did you ever ask the coach builder what the refrigerant capacity of the rear system is?

Oh btw, your profile still reads "1996 Fleetwood 44" Stretch; '02 TA, '95 Nighthawk, '95 F150" :D

08-18-11, 12:25 PM
Is there a switch panel in place of the left center dash vent on this limo? Did you ever ask the coach builder what the refrigerant capacity of the rear system is?

Oh btw, your profile still reads "1996 Fleetwood 44" Stretch; '02 TA, '95 Nighthawk, '95 F150" :D

I need to fix my profile :-)

I didn't think to ask the coach builder the system capacity. Superior put a label right on the accumulator that said how much additional refrigerant was needed (of course I don't recall how much it was). I was just charging it up to the manual's recommended pressures. The pressures fluctuate a lot depending on whether the fan is running or not. I know it's still undercharged, but I need to consult the manual to see whether I should be checking the pressure with the fan running or not.

And there is no switch panel in place of the center vent. They put the switches in panels under the dash and one mounted to the ash tray (odd, but kind of neat too).

There's just not much volume out of the vents, I think even less than the '96. I can hear the fan go to full blast when I turn it down to 60, but there's barely anything coming out. On the '96 I would just use the rear to augment things, but this one has a partition which makes the air circulation harder.

08-22-11, 06:48 PM

I spent hours installing the new fans. They had wider mounting points, despite being 12" fans like the original limo-builder installed fans. I had to dismantle the entire front end of the car to get the aux a/c condenser out (to which one fan was mounted) as well as the 2nd fan. The 2nd fan was mounted behind an external trans cooler. Did some fabrication work on the brackets and put it all back together.

Got them both installed and hooked them up to what should have been a 12V, key-on feed that comes from the limo fuse panel. Nope. No juice. Found a blown fuse in the limo fuse panel. Replaced it. No dice.

Now I have no power in the rear of the car at all. The 80 amp fuse I installed is good, and I've got juice to the big lead that runs to the limo fuse panel in the back. Something must have shorted. On the one hand I'm glad there was no fire. On the other, the whole back of the car is out. There's a main disconnect that I can almost get at. Looks like a 76 amp relay sort of thing. Might be a big breaker. Would be easier to take the passenger seat out (again), but I'm worn out.

It's broke til tomorrow. But the new fans look great!

08-23-11, 03:08 PM
So I'm replying to myself, but like I said this site is a diary of sorts. I can come back later once I've forgotten what I've done.

The rear power is controlled by a 75 amp relay connected to the big fat wire that comes off the battery. I feel better now that I put a fuse out by the battery. Anyway, the relay wasn't working so there was no power getting to the rear fuse panel (making a long story short - this revelation came after hours of investigation). What powers the relay? The A/C compressor fuse, of course. Makes no sense to me, but that's how they wired it up. What else is on the A/C compressor fuse? The manual cooling fan switch.

I had an "ah ha!" moment. Thinking I was smart, I had replaced the old switch with a new one. The old one apparently was supposed to light up but didn't anymore. I replaced it with one that did. This new switch is causing problems.

Now here is where things get confusing.

That switch only switches ground. That is, one terminal is ground, the other goes to the ground side of a fan relay. Also connected to that same ground circuit is a high-pressure A/C swtich. It also switches to ground. So both switches complete a ground. No big deal. If I hook 12V up to that switch to illuminate it when it's on, it works fine until the high pressure switch closes. Then it shorts out and blows the A/C fuse.

If I switch the ground and relay wires around (leaving the 12V wire in place), it works fine when it's turned on and illuminated, but shorts out and blows the fuse when I shut it off. Crazy stuff.

It makes my head hurt to think about what's going on so I just unhooked the 12V to it. So it doesn't light up. It functions like it should - turns the fans on and off. And the fans come on with the high pressure switch, too.

Both fans running keeps the A/C cool at idle, which was what I was going for. Wiring it up like the coach builder did was a bit of a nosebleed, but it's a pretty cool setup.

The only thing I haven't installed yet is the temp sensor. Once that's done, it will be just the way the coach builder designed it. Except for the illuminated switch, which will keep me up at night until I figure it out.

EDIT: Oh yeah. During all this we had an earthquake. The car was rocking back and forth - I thought there was something horribly wrong with it, or that I was hallucinating. I shrugged it off until people started calling me saying "did you feel THAT?!". Crazy stuff.

08-23-11, 04:13 PM
That must have been some Earthquake, because I felt it here too....around 2:00pm....the whole office building shook and I had stuff fall off my desk.....and I'm outside of Toronto!

08-23-11, 06:14 PM
It was the biggest quake I've ever felt here. Apparently the biggest to hit the East since the 1800s.

So now I have a weird smell coming from the HVAC system. Almost a burning smell, but not really. Not sure if the blower controller is on the way out, or the blower motor, but something doesn't smell right. I may have poked a hole in the evap core, but it would have drained itself by now. Compressor is still running and the air is cool.

I put the temp controller in. It's adjustable from 160 to 240 degrees. I turned it all the way up to 240 for now.

It wasn't a totally necessary job, but I'm glad I did it. The A/C should work better at idle now.

08-24-11, 12:17 PM
Here's the post mortem and pics:

New fans. I had to use the ties (which I hate) to install the one on the aux condenser. It was just too tough to modify that mounting bracket because it's part of the condenser.


I used Jeg's temperature controller in place of the failed one that the limo builder had installed:


All of the wiring used to be in these looms by the air box. I'll tuck it back in there one of these days. I soldered where I could, and used butt connectors on the less critical connections:

I used Jeg's dual fan installation kit which came with 2 relays and relay holders. It's virtually identical to the limo builder's setup, which I hastily cut out. I should have left it all in place - would have been a lot easier and less expensive. But, initially I thought I would reduce it to a much simpler arrangement. But, once I got thinking about it I decided to reconstruct their original plan (manual fan control, temp fan control and a/c pressure fan control).


Now I think the blower fan is failing. It smells "hot" and is grinding a bit.

On to the next project.....