Evap assist fan install in floorboard

mthomas58 · 05:28 PM

Taking the lead from Jim Sims and others, I installed a fan in front of the evap resistor intake, using a slightly different method, in an effort to increase airflow through the vents.

I had intended to install a 74CFM computer fan....but couldn't resist trying the new Spal 4" motorcycle/ATV fan that I was planning to install on the rear condenser that delivers 124CFM with an amp draw of 1.9. Build quality and CFM are sooooo much better. Only drawback is the fan noise. On fan speed 1 & 2 the fan noise is very noticable. Somewhat noticable at speed 3 and not at all at 4. I may go back and line the floor board panels with 1/8' dynamat foam for sound dampening.

I cut new floorboard panels (2) out of scrap paneling and mounted the fan directly in front of the resistor pack opening. I've got so much wiring behind the floorboard that I doubt I was getting good airflow to begin with. The using 1 x 2 stock, I built up another layer of floorboard to allow air to enter behind the carpeting. If I can't live with the fan noise, I'll swap out the Spal for the computer fan but I REALLY like the Spal!

I wired the fan to the front condenser fan so it cycles on and off with the compressor. Here's a few pics of the install.

david914 · 03-18-2007, 05:31 PM

Yeah, server's acting weird. I sent an e-mail to Pelican. Hopefully it'll clear up soon.

BTW, nice setup! Hopefully it'll help this Summer!

Loaded · 03-18-2007, 05:35 PM

What does this do? I just searched and couldnt find anything.

mthomas58 · 03-18-2007, 06:53 PM

It increases the velocity of the air at the intake which, in theory, should increase the velocity of the A/C vents output. Here is a pic of the fan......much heavier build and motor than a computer muffin fan.

Jim Sims · 03-18-2007, 07:22 PM

Nice work. Jim

mthomas58 · 03-20-2007, 08:52 AM

Correction on my fan speed comments. The factory A/C blower switch has only three speeds as position 1 is off. Therefore, evap assist fan in the floorboard can be heard at position 2 only. Not at all at 3 and 4.

Will definitely keep in place - fan noise is absolutely not an issue.

mthomas58 · 04-08-2007, 05:55 PM

Update: assist fan is working great, however, 1-1/2 air space between the floorboards is too small. There's too much suction on the top board causing the fan to draw more current and blow fuse (tapped into 7.5amp in-line fuse at front condenser fan).

Just widened airspace another inch and vented top support to draw more air. Air appears to be nearly free flowing now. It's amazing how much this 4" fan draws. These spal fans are awesome!

Can't wait for 90 degree temps to see how my mods work.

Mysterytrain · 04-08-2007, 06:10 PM

Mark, did you make a sealed duct for the air that is exiting the spal fan and direct it into the evaporator opening? I would think you would want to draw as much as possible from the front side of the fan and force it all into the original opening without it leaking around the backside of the floor board. Just thinking out loud. Nice work!!

mthomas58 · 04-08-2007, 06:29 PM

Good question. Thought about it but decided against it because the evap box is not sealed.....there is another approx 2-1/2 inlet at the tunnel (and I'm sure the orig foam seal to the box is toast). Addtionally, I've got so much crap crowded around the resistor pack opening that there is not a whole lot of room for air to go anywhere but in the evaporator. I may address this at a later date.

With the fan and A/C running, if I run my hand around the perimeter of the floorboard, the system seems to be pulling air all around.

mthomas58 · 04-21-2007, 03:31 PM

Quote:

Originally posted by Mysterytrain
Mark, did you make a sealed duct for the air that is exiting the spal fan and direct it into the evaporator opening? I would think you would want to draw as much as possible from the front side of the fan and force it all into the original opening without it leaking around the backside of the floor board. Just thinking out loud. Nice work!!

Have been thinking about sealing the floorboard since the last post to keep air from leaking out behind the floorboards. Pulled top floorboard up today to do some checking and there was qite a bit of air leaking out from behind the floorboard particulary around the mass of wires on the left and top. Stuffed some paper towels in at the leaks temporarily to test. Significant reduction in air escaping. Will monitor system for any performance improvements. Still waiting for a really hot day to arrive here in Atlanta.

mthomas58 · 04-22-2007, 07:43 PM

Quote:

Originally posted by mthomas58
Have been thinking about sealing the floorboard since the last post to keep air from leaking out behind the floorboards. Pulled top floorboard up today to do some checking and there was qite a bit of air leaking out from behind the floorboard particulary around the mass of wires on the left and top. Stuffed some paper towels in at the leaks temporarily to test. Significant reduction in air escaping. Will monitor system for any performance improvements. Still waiting for a really hot day to arrive here in Atlanta.

Quick update: sealing up the floorboard proved to be a bad idea....car did not cool as well (significantly). I think the reason is that the floorboard fan CFM is less than the A/C blower thereby restricing airflow and efficiency at high speed (without the ability to pull from the sides as needed).

It was about 80 today here in Atlanta. With the floorboard sealed, I could not get vent temps much below 40. Pulled the paper towel insulation and vent temps got down to 36 in a couple of minutes.

Jetjockey · 02-22-2010, 08:42 AM

Here is a floorboard that will improve flow back to the evap box if installed without carpet.