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AC Fan in a '75 K5

Discussion in 'The Garage' started by BEHJR, Jul 15, 2003.

  1. BEHJR

    BEHJR 1/2 ton status

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    AC Fan in a \'75 K5

    Just got the K5 and the A/C works (I didn't believe it).

    Newer cars have higher output fans. Am wondering if anyone knows of such for a replacement. Or are the components such that it would be pissin up a rope, ie moving the air too fast across the coils for the air to cool.

    Comments, thoughts, suggestions welcome.

    PS. A/C is a must when it is too hot with the top off. Gotta love Texas summers.

    Thanks.

    BH.

    /forums/images/graemlins/ears.gif
     
  2. redk5

    redk5 Registered Member

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    Re: AC Fan in a \'75 K5

    I't may be possible to bypass the resistor in the existing fan, this would give nothing but a high setting but will reduce the life of the fan, the only other thing i can think of is to find a fan out of a bigger vehicle that may have larger fan fins, (suburban?) I'm not to familiar with the fan sytems on other gm trucks though. Try calling a gm dealer.
     
  3. BEHJR

    BEHJR 1/2 ton status

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    Re: AC Fan in a \'75 K5

    The settings on the fan work fine, lol. I am amazed. Just trying to push more volumn of air through and have it cooler and a bit quicker.
     
  4. RustBuket

    RustBuket 1/2 ton status

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    Re: AC Fan in a \'75 K5

    Rig up a 14hp bin fan..... /forums/images/graemlins/grin.gif Those'll practically blow you into the back seat! Mind you, you'd need quite the set up for an alternator!
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: AC Fan in a \'75 K5

    The setups already have straight 12V (actually whatever the system is at, 12-14V typically) in the "high" position, but the difference between AC and non-AC is the squirrel cage size, and the way the motor is wound. (at least from my RC car days, motor winding was what controlled RPM at the same voltage)

    I think you'd be pissing up a rope. You can try newer Camaro's and what not in the wrecking yards, but I'd be fairly surprised if GM ever increased the speed of the fans beyond what the AC setups had. They started out with cooling to the AC fan motors, so that tells me they probably were on the border of the capabilities of the motor size they were using when they designed it. (at least in terms of longevity, sound, etc)

    Fan motors such as ours were used probably WELL into the 90's, so later ones may have a bit of an advantage against a '75, but I wouldn't bet money on it. They are so common that I'd get my hands on one or two newer ones and try them back to back. (friends cars, etc.) You'll notice that GM didn't change the motor mounting (at least most of the time) between FWD cars, RWD cars, and trucks, so you have an almost unlimited source for them.

    Just make sure it's an AC fan, as the non-AC motors are definitely a different speed.
     
  6. K5 NUTT

    K5 NUTT 1/2 ton status

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    Re: AC Fan in a \'75 K5

    Swapped in the blower motor from my 76 K5 to the wifes 90 burb...they look the same except the way the squirrel cage attaches to the shaft....however the cage fins are at a deeper angle than the early units....so when i buy the replacement for the 76 it'll be for the 90 v2500 burb by application...

    Also as far as a/c goes...
    1) Add a 10" condensor fan to help cool the refriderant down....
    2) Hook a vacum operated heater valve in with the cowls fresh air door vacum pot so when you go to max air you shut off the hot water and the fresh air together...
    3) Late model p/u-burbs-vans all have neoprene covers over the accumulator...to keep engine heat from boiling the refriderant...you can do the same with insulation and metal tape...and doing the entire suction line doesn't hurt by the way...

    4) Line the outside of the evaporator housing with some sort of heat shielding also...there again making an igloo for the evap....

    5) Maintenance...which never gets done....remove grille...fin comb bent fins on condensor....use shop air first and then a trip to the carwash to hose out the cores ie: rad...cond....this makes a dramatic diff....you can see how the cond fan will help by watering down the cond and watching the discharge psi on a set of gauges and instantly see the results on the dash temp...

    DW
     

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