Starcool AC Blower Fan

adamwcordell · 09-09-2022, 08:12 PM

Hey All,

I had the blower fan on my starcool system seize up and was blowing the 20 amp fuse on my Starcool panel.

Anyways I wired in a replacement and realized that it's sucking air not blowing... Didn't pay much attention on the install for +/- leads just matched blue to blue black to black but now I'm having second thoughts... lol

Picture attached.

Should this thing suck air or blow air?

adamwcordell · 09-09-2022, 10:17 PM

Welp. It's backwards.

https://www.sportsmobileforum.com/forums/f19/quick-starcool-fan-question-10309.html

**daveb** · 09-10-2022, 10:10 AM

Probably the same as my starcool electric radiator fan. Somehow it was hooked up backwards and my mechanic had to reverse the leads. Huge difference in the air duct temperature while at idle or in slow traffic after reversing the flow. Trying to blow air against the natural flow as I was driving didn't work well.

adamwcordell · 09-11-2022, 08:39 AM

Yup that's exactly what I had to do. I also had to flip the fan blade, which was a head scratcher for a minute but i think i finally got it all figured.

capnkurt · 09-12-2022, 12:14 PM

This whole front fan thing has me wondering why so many of these were hooked up to blow toward the front of the vehicle (pulling air from inside of the engine bay and pushing it forward). My Starcool was (and still is) set up the same way. Seems to me that Sportsmobile would have a good reason for making it so, but then again mistakes are often made.

However, it got me wondering if the reason has to do with the fact that while parked and on shore power, it might be a better setup to pull air OUT of the engine compartment rather than put more hot air inside of it. When you think about it, wouldn't it be better to take the heat from the condenser and put it outside where it can quickly dissipate, as opposed to packing it into the engine bay where it would likely not be able to escape as easily? It would also heat underhood components and allow for more heat transfer from the engine bay into the interior of the vehicle. I'm theorizing, of course, as I am no fluid dynamic specialist by any means. So, for cooling the van when parked and the engine is cold, might it not be better to run the fan so that it's blowing forward?

This obviously leaves the setup undesirable for driving, when the front-blowing fan is fighting against both the engine-driven radiator fan's forces and the general airflow while in motion. Perhaps wiring it to blow forward was seen as a good compromise? While driving, the relatively small force of the Starcool fan doesn't have a chance at overcoming/defeating the relatively large volume of air that moves rearward though the radiator/condenser as a result of driving force and the much bigger radiator fan's capacity. Perhaps, while not as efficient while driving, the forward blowing fan is really intended more for shore power cooling?

I certainly don't know, especially since SMB has said that it was a mistake to have the fan blowing forward (according to a couple of posts I read). It just got me wondering...

thoughts?

adamwcordell · 09-12-2022, 02:38 PM

I mean you could be correct about evacuating the air from the engine compartment being the thought process.

My thinking was -

The fins on the condenser are designed to conduct heat out of the condenser, then once the heat is in the fin it's convected away via airflow.

Q = h*A*(t2-t1)

Q is heat transfer
h = convective heat transfer coefficient (dependent on several parameters)
A = area of fin
t2 = fin temp
t1 = temp of air blowing over the fin

The larger t2-t1 is the more heat is transferred, which is obvious. Basically you want the coldest air possible going over the fin.

h has it's own parameters which define it, one of which being Reynolds number which largely depends on speed of the fluid (air moving over the fin in our case)..

It's an optimization problem really. You want the fastest coldest air. You can't get any colder than the outside air temp so you want air closest to that temp as possible blowing over your fin and you want it to be moving fast as possible. I think it makes sense to suck the air from outside, away from the hot or hotish block which would warm the air up, and force it over the fins. I dunno I'm rambling trying to remember my heat transfer courses from college at this point. Bottom line, I'm not switching it back hahaha

**daveb** · 09-12-2022, 06:06 PM

Well in my case I don't think it was SMB who hooked the fan up backwards, it was probably Freedom Ford of Fresno. That was the reason the fan didn't have to be changed because I'm guessing it was built correctly at SMB. Ford simply reversed the leads. During hot weather in slow traffic the air got a bit warm. After my AC guy reversed the polarity, it made a big difference and ran like it did before going into the Ford shop.

capnkurt · 09-13-2022, 05:51 PM

That's good to know, Dave. I've had the same issue with mine...that is, while in slow traffic the A/C doesn't work as well. My fan's blades are correctly oriented such that they are designed to be pushing the air rearward through the radiator, so I'm going to switch my wires and see if it improves anything.

**daveb** · 09-13-2022, 08:48 PM

It still cools less during hot weather in stop and go traffic, just keeps the AC system cooler especially when the engine fan isn't pulling air through. Not sure if SMB installs the fan in different configurations depending on make/model or year, but it makes sense to bring the cooler outside air over the fins and into the engine bay.