I finally got my AC back up and running but it just does not blow real hard. I still have the R-12 and it is very cold but I really wish it would blow harder. The car is a 79 and I have to assume that the fan blower motor fan is original. Do they make faster ones? I know that all my ducting under my dash is not air tight, would that make that big of a difference?

The fan does work in all speeds so it is working right.
I do have a valve in my engine compartment shutting fluid to my heater core. I replaced my fresh air vent gasket down by the passenger side kick panel so I know that I don't have air coming in there.

Just need more airflow! Ideas?

Dan

 

Replace it with a C4 blower and fan. Cheap and easy to do. Do a search here, there is a very good thread on this.

 

CHarper,
I see that there is another thread right below mine about this same thing. I asked someone else where they got their C4 blower and fan and if it was a direct fit or if he had to do some mods.

Thanks for your help

 

Bought Mine off eBay for less than $25.00. The squrrel cage is about 1inch longer than the original so you need to make a spacer to accommodate the length. Some use wood and cut it from a pattern made from the old one. I found a piece of plastic like material at Lowes and used a Dremel tool to cut it. Easy mod that helped my 82 a lot and only took a couple of hours. Much easier if you remove the radiator overflow tank.

 

Sounds like a new project. I read on another thread here that they upgraded the ground wire to a heavier gauge and it sped it up even more. Did you do that? I have never pulled the motor or even looked at it so I am not sure where the wires are at except for the resister on top. Maybe I will look at it this week.

Was the c4 motor a direct fit in regards to the wiring?

 

you may also need to check your evaporator core, it may be partially clogged with leaves, dirt, etc.,

 

First thing I'd do is make sure the rest of your system is working right. Are the doors opening and closing when they should, are they sealing, that kind of thing. I replaced the blower motor on my 81 with one thats for an 81. Blows really, really well, and I didn't have to build the spacer the C4 blowers need to have.

 

I will do that also. It is pretty clean, a few leaves and such but not that many.

 

here is info about c4 blower motor install w/ spacer.

http://forums.corvetteforum.com/c3-t...r-install.html

 

Reading it now. Thanks

 

I was way less than impressed by any increase in air flow that I got when I went to a newer blower motor, added the spacer, etc. Just sayin....look for anything and everything else first, then the motor.

 

Most of things the seals in the ductwork died when the car was 2 years old, plus the duct pieces didn't fit to well to start with. I put in a C4 fan while I had it all apart and it really did blow a lot better than the 30 year old stock unit. I am also fixing all the ducts while reassembling. I have some doubts about upgrading the ground wire fixing anything, the wire size should have been good to go. Make sure all the dead leaves and lizards have been cleaned out of the evaporator and that the duct doors all work

 

the newer gm passenger cars have blower wheels with 43 blades . not aware if the motor has more power, but on full blast it will knock your comb over off. the cars cool down very quickly, but of course the wheel is larger than the 30 blade wheel. something to muddle over.

 

check your duct work first.the duct connections are not verry tight .if that is all good and you still want more air ,do the c4 fan.i would look in to the new 43 vain fans that gm is using .

 

I have a 1971 that I did a frame off restoration. I have never been pleased with the air flow even after replacing all of the seals etc. So I read the forums and bought a 1990 C4 blower motor from Autozone for $29. The fan diameter is the same as a C3 but as mentioned is about 1 inch longer. I made a spacer using 3/4" MDF wood and used a jig saw to cut it out. I installed the motor and wired it up. First the motor was running backwards so I had to switch the wires. After that, I noticed very little difference. I turned on the blower on high speed and checked the evaporator housing. I was losing all kinds of air around the evap housing especially where the fan is located. So I took out the fan, and reached inside with a tube of silicone sealer and sealed up the entire circumference where the blower wheel operates. I found a couple of other areas leaking by the wiper door actuator area and sealed those as well. This made a HUGE difference in airflow from the vents inside the car. Then I checked to make sure the max air door and other door actuators were working. I found that they were barely working yet I tested each of the vacuum motors before I installed the interior plenum assembly. After checking with a vacuum tester, I found the engine vacuum supply line where it comes out of the firewall near the distributor was pretty much deformed shut. I assume the heat over the years softened up the hose enough to where when vacuum was applied, it actually sucked itseft shut. I spliced in a new section of hose and presto, all of my heat and ac doors work perfectly. I just finished all of this today and I'll tell you that I'm extremely happy with the air flow now. In addition to all of the other posts, I hope this information will help others when diagnosing this issue.