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    #1

    Underdrive pullies and AC performance

    Dear Panthers,
    Scott has thoroughly worked up and rebuilt my A/C system (New compressor, condensor etc). He also installed an underdrive pulley. The A/C works okay (though not terribly cold) so long as I'm at medium to high RPM's. If I'm stuck in traffic or cooling the car with four dogs while I'm inside the supermarket, it is no better than opening the windows and hoping for a breeze. My high dollar new system is worse than my stock 92 Subaru A/C.

    I (who does not change his own plugs) have a theory how this might be fixed and would be grateful for your opinions.

    I think that becuase of the underdrive pulley that the compressor isn't spinning fast enough to generate major cool.

    What would happen if Scott installed a smaller compressor pulley? It's spin harder, cool better and I could chill my Buds in front of the vents. Yes?

    Donald McCaig
    Tags: None
    #2
    Originally posted by yucatec View Post
    Dear Panthers,
    Scott has thoroughly worked up and rebuilt my A/C system (New compressor, condensor etc). He also installed an underdrive pulley. The A/C works okay (though not terribly cold) so long as I'm at medium to high RPM's. If I'm stuck in traffic or cooling the car with four dogs while I'm inside the supermarket, it is no better than opening the windows and hoping for a breeze. My high dollar new system is worse than my stock 92 Subaru A/C.

    I (who does not change his own plugs) have a theory how this might be fixed and would be grateful for your opinions.

    I think that becuase of the underdrive pulley that the compressor isn't spinning fast enough to generate major cool.

    What would happen if Scott installed a smaller compressor pulley? It's spin harder, cool better and I could chill my Buds in front of the vents. Yes?

    Donald McCaig

    I get about 45 at the vents at idle with the underdrive pulley. Before I installed that, I got about 42 degrees, so there is a slight performance hit with the UD pulley. 3 degrees isn't really that substantial though. A smaller compressor pulley might help, but I think it would probably be harder finding one than anything else. The pulley and clutch is somewhat integrated, and I don't believe it would be possible to swap just the pulley for a smaller one without replacing the clutch assembly too. Finding something that fits on the Panther compressor with a smaller pulley diameter may also be a problem.

    I think in your case more fan might be the answer. I'm using a Mark VIII fan that covers probably 90% of the radiator. Theres about 2-3" of width not covered. It moves enough air that I can feel a breeze coming from under the car if I'm standing at the driver's door. With more fan I think you'd actually get better cooling than I get since your evaporator and condensor are new, while mine are not. Its also possible that some marginal improvements could be made by better sealing the area between condensor and radiator. This would force more air to flow through the condensor instead of around it. The factory used these tarboard looking things that just sit up against the side of the radiator to do this, but they weren't that great 20 years ago and I'm sure by now are really not doing much. I doubt it would be a huge change, but if the goal is optimal AC performance it would be worth it I think. It would be pretty easy too I think, probably some foam rubber could be made up into a gasket of sorts to prevent air from being pulled through the space between the parts.


    Vaguely related comparison. This weekend amongst other repairs to my Chevy S10, the fan clutch was replaced. The old one was completely shot. At idle, the AC was really lousy in the truck, and at low speeds it wasn't too great either. Highway was OK. With the new clutch installed, it gets so cold that its actually uncomfortable. The amount of air moving across that condensor hugely affects the system performance.

    also splitting this thread off for more visibility.
    Last edited by gadget73; 07-20-2008, 10:39 PM.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Comment

      #3
      yea i dont think that the electric fan that i installed moves enough air across the entire ac condensor.....i have a few ideas for better fans.....i thought that one would be sufficient, but it isnt enough air to cool the ac condensor and the radiator

      1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
      2006 Lincoln Town Car Signature. Stock for now
      1989 Ford F-250 4x4 much much more to come, sefi converted so far.
      1986 Toyota pickup with LSC wheels and 225/60/16 tires.
      2008 Hyundai Elantra future Revcon toad
      1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

      please be patient, rebuilding an empire!

      Comment

        #4
        Originally posted by lincolnmania View Post
        yea i dont think that the electric fan that i installed moves enough air across the entire ac condensor.....i have a few ideas for better fans.....i thought that one would be sufficient, but it isnt enough air to cool the ac condensor and the radiator
        I believe I'm running the same fan as Yucatech. 15" Proform for a Mustang. I'll say, I'm not really impressed with it. Seems to handle my '88 GM just enough to get by. Had the '88 out on a long trip yesterday in the heat and the A/C wasn't as cool as I had thought it should be, either. It's probably due for a recharge, though, so I can't say it's all a fan issue. The fan ran pretty much all the way home, too.

        Comment

          #5
          My $90 A/C revamp (with a used accum., no new orifice tube, etc), netted me 38 deg F at the vents, as checked with a meat thermometer. I added an e fan to blow the heat off the condensor, and noted no difference; it was a cheap 1000 cfm Proform fan.

          I was a hack, and used the tie raps included in the kit to mount the fan to the condensor, and I believe they chaffed a hole in my condesor. The A/C is no longer as cold as it should be, but I haven't dug into the root cause yet. Next year. New hoses, and everything; watch, it will probably blow warmer.
          **2012 Ford Mustang Boss 302: 5.0/ 6 spd/ 3.73s, 20K Cruiser
          **2006 MGM,"Ultimate": 4.6/ 2.73/ Dark Tint, Magnaflows, 19s, 115K Daily Driver
          **2012 Harley Davidson Wide Glide (FXDWG):103/ Cobra Speedsters/ Cosmetics, 9K Poseur HD Rider
          **1976 Ford F-150 4WD: 360, 4 spd, 3.50s, factory A/C, 4" lift, Bilsteins, US Indy Mags, 35s Truck Duties

          Comment

            #6
            Dear Panthers,
            I tested my A/C yesterday. Engine temp 185, outside temp 84, at idle w/ Max A/C: 68 degrees at the vents.

            Donald McCaig

            Comment

              #7
              ugha.........yea i think that the electric fan just isnt moving enough air..........shame is that the factory e-fans wont fit in there cause of the heavy duty radiator
              i need to relocate the transmission and the power steering coolers also to somewhere else than in front of the ac condensor

              1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
              2006 Lincoln Town Car Signature. Stock for now
              1989 Ford F-250 4x4 much much more to come, sefi converted so far.
              1986 Toyota pickup with LSC wheels and 225/60/16 tires.
              2008 Hyundai Elantra future Revcon toad
              1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

              please be patient, rebuilding an empire!

              Comment

                #8
                oh wow, yeah that would definitely be why its not performing. I get temps in the 40s at my dash vents with an underdrive pulley.
                86 Lincoln Town Car (Galactica).
                5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                91 Lincoln Mark VII LSC grandpa spec white and cranberry

                1984 Lincoln Continental TurboDiesel - rolls coal

                Originally posted by phayzer5
                I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                Comment

                  #9
                  Sounds like it needs some pushers in front of the condensor. Could just make a relay setup that turns on a pusher when the AC is on.
                  Builder/Owner of Badass Panther Wagons

                  Busy maintaining a fleet of Fords

                  Comment

                    #10
                    Dear Panthers,
                    To enrich the confusion . . .

                    Comment

                      #11
                      Dear Panthers,
                      Sorry about that post. This morning was chilly in the mountains so I turned on the heat. At 180 engine temp, I couldn't tell if the fan was wafting warmish air unless I put my hand directly over the vents. Apparently a hot summer is going to become a cold winter.
                      Donald McCaig

                      Comment

                        #12
                        I wonder if that blend door in the dash is stuck. I know you've got a cable operated one since its not automatic, but its possible either the flap broke off the lever that moves it, or maybe the cable snapped or something and the whole problem is the blend door isn't being moved with the temperature lever. If that door is stuck somewhere in the middle, you'd get lousy heat and ac performance.
                        86 Lincoln Town Car (Galactica).
                        5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                        91 Lincoln Mark VII LSC grandpa spec white and cranberry

                        1984 Lincoln Continental TurboDiesel - rolls coal

                        Originally posted by phayzer5
                        I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                        Comment

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