A/C question for anyone out there.

Jared at Pelican Parts · 07-25-2003, 12:14 PM

Question:

It occured to me that i've never actually seen my aux. fan come on during regular driving, however it does come on when the A/C is activated. Now what im thinking here is that the fan would help operation of the A/C system, by lowering the temperature of the gas entering the condensor.

From what i understand, the aux. fan has two speeds, and it always switched on low when the A/C is on, and that high only kicks in when the temperature is hot enoguh to trip the fan switch.

So, if I were to increase the fan speed, the A/C would most likely blow colder from more air being drawn through the condensor.

My idea is to take a switch, mount it somewhere on the dash then tie it into the leads for the fan switch on the radiator, essentially giving the switch a manual control, to kick on the fan to high speed.

Anyone have any input on this?

carolinus · 07-25-2003, 05:06 PM

Well, it sounds like it might work. You could be at the maximum cooling capacity of your system already, though, and find it a waste of time. An AC unit works by compressing gas at one end, and expanding it on the other. The compression heats the gas, and thus a cooler is needed. Then, the expansion cools it, and a heater (air blown through your vents) is needed. If you are already cooling it at the maximum possible rate for your compression system, you won't get anywhere. This is a factor of the volume capabilities of your expansion orifice or valve. If your system is compressed to xxpsi, and then expanded to yypsi, cooling the temperature of the xxpsi won't help unless your compression setup can compress more, and your expansion setup can expand more. Generally, neither is variable to a great degree. Are you unhappy w/ your cooling system as is? If so, you might want to try some of the Autofrost stuff. It is REALLY out there in cooling capabilites.

see http://www.autofrost.com/oil/

Manny · 07-26-2003, 11:28 PM

It will work just fine. I got this setup on my car for at least two years now. The key is to have a minimum of 60 psi drop from high side to low side. So let's say that you have high air volume flowing across the condenser that you high side pressure is at 125psi. This amounts to ~105 deg F condensing temperature. Then on the low side you would like your expansion device to lower the pressure to ~25psi to maintain a boiling temperature of 25 deg F. This will give you a difference of 80 psi. Additionally, you compressor will love you to death because it does not have to work as hard.

carolinus · 07-27-2003, 05:12 AM

Well, since someone else had tried it and had good luck, I will probably give it a go as well.

Jared at Pelican Parts · 07-28-2003, 09:21 AM

Im going to do this after work today. I'll let you know how it goes...

Jared at Pelican Parts · 09-30-2003, 03:39 PM

I re wired the aux. fan to kick on hiogh speed whenever the A/C is activated.

A HUGE difference in the way the A/C works at idle in the heat. You can feel the difference almost automatically. It just so happens I did the switch out f sheer frustration and discomfort, being stuck in traffic on the 101 in the San Fernando Valley, temps reaching 105 Degrees. I pulled off the freeway to find the nearest Radio Shack, bought wire jumpers and a switch, used my wiring tools (I alwas carry a tool kit in the car) to tie into the wiring for the high speed fan, tripped the switch and voila! instant cool...

If anyone would like a wiring diagram showing how exactly to do this, please email me at jared@pelicanparts.com

Manny · 09-30-2003, 05:30 PM

He, he. I told you it will work. What took you so long?

Jared at Pelican Parts · 10-01-2003, 07:16 AM

I actually did it a few months back, I just havent had time to post the results. Working on many projects simultaneously.