Is there any kind of aftermarket "booster" or replacement fan that dramatically boosts the air conditioner air flow output from virtually non-existant to reasonable on a 1974 vette? :seeya

 

We are installing a C-5 corvette blower in my 74 Today...I will let you know about the improvement if we get it in.....the blowers on the mid seventies vettes are worthless

 

Dan, I've been doing a lot of work on my system, and feel your pain. The best thing I did was seal up all my duct leaks. The evaporator case had a crack where the engine or head had been run into it during a major repair plus the case itself was not sealed (or secured properly, for that matter) to the firewall. In addition, when I had the dash apart to replace my heater core, I found that all the ducts (which have a terrible fit and finish from the factory) had lost their seals somewhere along the line. Needless to say, I had NO airflow :mad !

I used close cell foam that was cut and glued to the various stock places, and then I duct taped the outside of the joints as well with aluminum duct tape. I replaced the fan motor with a new one, and used a NAPA squirrel cage (it has more fins and a better contour than the original) and I now have what I would call good air flow out of my vents and defroster. I may still use the later (C-4) fan & cage assembly (with a custom spacer) that others have tried with some increase in air volume. Also, I have really insulated the floor and tunnel on both sides with excellent results! I actually NEED the heater now if I use the car on cool evenings :rolleyes: . I don't have the A/C compressor mounted yet, and I still need to have R-134A compatible hoses made, so I'll have to wait for the results of that effort. I'm confident that it will work well.

Most of the stuff I did was detailed in Michael Davis' book "A/C strategies for the 68-82 Corvette", available from the Classic Motorbooks' web site. Good luck.

Hans

 

Dan,

Either Vette Mag or Corvette Fever did an excellent article about 2 mos ago on improving A/C airflow in C3's. If you don't subscribe, go buy one and order it. :seeya

 

On my '72 convettible I noticed a large aluminum block with passages in it directly in the airflow stream, near the front of the housing discharge path...
I never found out what/how controlled it...all I saw was a blockage...so I removed it....and increased the airflow a good bit....another thing to do is seal the outside air flapper door shut, I used RTV, and wired it shut, disconnect and block all the vacuum lines to the inside and outside flappers, remove the inside flapper from the kickpanel, another airflow blockage....
sealing all the housings against under dash/firewall leakages is of course mantatory....
another thing is take that ground wire off the brass tab, solder a heavy 10 ga wire to it, and run it to the engine block direct...puts another 1.5 or so volts to the motor on hi speed....more air flow...another thing is make sure you get within one volt of the direct alternator output to the blower motor when on high speed...check the relay for bad/heated/weathered/fried connections, it's mounted on the evap housing, right above the exhaust headers, smart...duh!!!!

check for corrosion on that 30 amp white fuse holder near the horn relay/power distrubution block on the driver fender liner....
for that matter check the relay for voltage drop across the high speed contacts...
the power wire to the motor is also noted for overheating and causing power drops, and melting insulation in the process....

of course check for trash/leaves in the airbox pressure side....on the blower side of the evaporator....

I installed a new vac operated heater flow valve in one side of the heater lines...maybe should do both....but one seems ok....

now with carpet insulation underneath...it should be ice cold in there, unless of course the a/c isn't operating...another topic entirely....

GENE