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Speed control options on fans

Ecomike on Mon May 19, 2008 7:06 PM User is offlineView users profile

Year: 85
Make: Jeep
Model: Cherokee2.2
Engine Size: 2.2
Refrigerant Type: R-134a
Ambient Temp: 90 F
Pressure Low: NA
Pressure High: NA
Country of Origin: United States

I am looking for non OEM options for reducing electric AC condenser fan (aftermarket), and AC Blower OEM (rewired, bypassed the AC blower speed switch) loads on my alternator by reducing the fan and blower speeds. Anyone out there come up with some nice inexpensive solid state options?

I am thinking of 0-100% DC speed controllers, and even DC to DC solid state voltage converters to drop the motor voltage as possible options. I want to avoid the dropping resistor options.

I am planning to test the current draw of my fans at various voltages to find out where I need to be. I have a custom power plant (nissan sd22 diesel) in my jeep and the alternator (50 amp rated) is getting overloaded when I run the head lights, AC condenser fan and the AC blower on max speed and then tap on the brake lights. I live in Houston, so it gets very hot and humid here, very fast.

I do not need the AC condenser fan on all of the time, and it cools more than I need even at idle on a 95 F day at 80% humidity, so I am looking at slowing it down. Right now it runs off a fused toggle switch I installed. I would also like to find a more energy efficient way of reducing the AC blower fan speed than the coil wire resistor packs AMC used back in the 80's, located in the duct work. Their wiring of that speed control, fan speed switch, ignition switch, fuse box and so on was a poor design, wire, switch and contact size wise, and after 23 years it has many problem areas in the wiring and contacts, so I have it bypassed currently with a toggle switch, and 30 amp in line fuse right off the battery.

I have heard that some of the new vehicles have or had PWM (pulse width modulated) speed controls for the AC blowers, but I am not familiar with them. Who used them, which ones worked best and are the least expensive new?

94RX-7 on Mon May 19, 2008 10:49 PM User is offline

I've been researching various electric fan controllers for potential use on my truck. There are PWM controllers available from the major fan manufacturers such as Flex-a-Lite and Spal. I don't know how much it will cut your load, however. You can't get a bigger alternator I presume?

GM Tech on Tue May 20, 2008 8:05 AM User is offline

Why not just buy one out of a Cadillac (Eldorado/Seville)- like from an early 90's vintage-- I have two that I use to control head pressure for test purposes- my input is a variable potentiometer- so I can adjust to what ever fan speed I want. Cadillac used these to do exactly what you want to do- the fans run at whatever speed is deemed necessary. I have two leads to hook to the battery with clips- and two plugs that plug into the electric fans- then I adjust the variable pot to get whatever fan speed gives me my desired head pressure. Most of your work will be done for you and the salvage yard may sell the fan speed controller cheap- since they may not know what it is- or where it is located.......

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

bohica2xo on Tue May 20, 2008 6:52 PM User is offline

Jooo mean dees one GM?



15 bucks at Pick-A-Part. Or $202.79 at Rock Auto...

I grab them every time I see one for 15 bucks.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

GM Tech on Tue May 20, 2008 9:53 PM User is offline

Yeah Buddy!! Thad be the one!!!!

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

NickD on Wed May 21, 2008 3:43 PM User is offline

Ha, make your own, downstream is a circuit I designed for my blown out Caddy module, believe they call the OE version a POS whatever that means. Just get a couple of 555 timers, hook one as an astable to set the clock speed, around 100 hz, and use that to trigger a the second wired as a monostable with a timing pot for the pulse width, and use that output to fire up the circuit someplace below.

Circuit is still working great, it cut OE Vsat from 1.2 volts down to 0.2 volts, that's cool, both in performance and heat dissipation.

crf on Thu May 22, 2008 3:59 PM User is offline

Hi, would you mind posting the wiring diagram for the fan control module and the value of the potentiometer? Thanks

Ecomike on Sat May 24, 2008 3:48 PM User is offlineView users profile

Here is one I am looking at on Ebay, cheap, and already assembled.

http://cgi.ebay.ca/DC-Motor-Speed-Control-Controller-Electronic-30-Ampere_W0QQitemZ160240469400QQihZ006QQcategoryZ78197QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Where exactly is the GM module located? Any other years, or models that used them?

Any idea how much these units cut back the power draw? Anyone ever collected any test data at all?

Any one have a postable schematic of the pinouts for it?

Ecomike on Sun May 25, 2008 4:44 PM User is offlineView users profile

Here is a site rich with the electronic science involved with these.

http://homepages.which.net/~paul.hills/SpeedControl/SpeedControllersBody.html

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