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Getting Hotter in Texas

dk1977

Well-known member
Joined
Oct 5, 2004
Messages
77
Location
Trinity, TX
Corvette
1977 White Coupe
I have a '77 with factory air. I am trying to get any feedback on replacing the stock blower motor / fan with something with more power... I checked previous threads on this subject and it seems there are others with my problem; low air volume from the unit. I have replaced the motor, checked all the ducts and diverters and sealed the inner fender/fresh air box on the passengers side and replaced the hood seal. The air coming in the car (on vent) is relatively cool. When the weather (and the car) warms up, it seems the stock blower (on high) just can't put out enough air to keep up.
My GM truck ('02) can produce a great volume of air from the AC. Has anyone tried replacing the original blower with a later model motor / fan? I realize the constraints of the original housing size. Just wondering?
 
I always thought that HVAC on the sharks was an afterthought. The blowers are neanderthal in technology. If you can figure out a better mousetrap, I'd like to hear it. I have replaced my blower switch several times. The high function always craps out. I guess the engineers thought that the top down and t-tops out were the only way we'd drive out cars.
 
I did the upgrade with a 85 model fan and cage. The results weren't what I hoped. The biggest headache was finding the little rubber tube to cool the motor that would work. My nextstep is checking the evap. core
 
Did the '85 blower and cage fit with no mods to the original mounting? What is different about the '85..more air flow..more rpm? Mine "ok", but I was looking for a motor with more flow, similar to a newer model truck. I guess I will go to an auto parts store and look at newer motors / fans and see what differences there are.
Thanks for your input.
 
You have to fab a spacer,I made mine form a poly. type material. cage is much longer. Do a Forum search, but yours is most likely like mine. If I come up with something that helps I'll let you know
 
Here is a thread I saved that my offer some suggestions. Also, there is a similar article in one of the corvette magazines this month.

Like most of you I've battled the problem of cockpit heat. I think I've finally found a problem in my 74 that may be common to a lot of C3s and which may cause heat to come in to the cockpit no matter how much insulation or sealing is done to the heat/AC system.

Over time I've noticed that I always got an "engine" smell in the cockpit. I figured it was air coming out of the hood and being drawn into the heating system through the air intake in the wiper trough or air leaking into the system through the heater box.
  • I put a wiper cover on earlier this year and I could see that the hood sealed really well in this area so this shouldn't cause a problem with air leakage past the gasket.
  • Since I pulled my heat/AC system out last winter and resealed everything I discounted this as a cause for heat leakage also.
  • When doing the heating system I also installed a shutoff valve for the coolant.
  • I also insulated my entire cabin so I'm not getting heat through the floorboards or the body. This left the air intake on the system as a possible source.
  • I removed the right hand dash pad and kickpanel which exposed the flapper mechanism for the inside outside air control. I removed the vacuum motor and flapper mechanism by unbolting the two bolts that hold the motor, moving it out of the way, and unhinging the flapper. This is done by pulling down the top spring loaded pin, pushing the door into the fenderwell and twisting it so that it can be removed from the inside of the car.
  • I then started the engine with the hood closed and the heat/AC off. I felt hot air coming into the plenum from the engine compartment. This plenum is secured with the same adhesive that holds the rest of our body panels in place and like those the adhesive will dry and crack over time. Anyone who has dealt with stress cracks on the fenders can attest to this.
  • Remember also that air leaking into this plenum will be coming directly off the exhaust system and with headers the problem is exaggerated.
  • To seal this plenum I used windshield sealing caulk. You can get this at your local parts store for around $5 a roll. I used the cault to seal around the entire perimeter of the plenum, or as much as my arm would reach since you're working through the flapper hole. The most important areas to seal are the forward and lower area since that's where the majority of the heat will come from. The rear area is sealed against the forward door jam and really shouldn't leak hot air.
  • After doing this I repeated the test with the engine running and felt no heat entering the cockpit.
  • I reinstalled everything to complete the job.
I've only driven the car twice since then but I can tell you that there was a vast improvement. I took the car to work on a day when the temperature hit about 85 degrees. Before the fix I would have had to have the AC running or the heat would have been unbearable in the footwells and even worse with the t-tops off. I ran the car home that day with the t-tops off and the footwells were no hotter than the rest of the car. I've also noticed that the AC tends to run a little cooler by not having to fight the heat coming into the system.

So far I also haven't had that "engine" smell anymore. I'm hoping that as I use the car more, in different situations, I'll be able to report more benefits from this fix but until then I thought I'd give a heads up to everyone. For details on the cockpit insulation go to my website. You'll see the article on insulation and also what you have to remove to reseal the heater box.
 
The 95 has a two wire hookup,thats why I went with the 80 something. Cage and all was pretty close to the 95. The resistor theroy sounds like a good one cause I hooked up my old fan to a battery and it spun like crazy
 
There are a lot of issues on cooling these old cars from heat being introduced into the car from the engine compartment to the low air flow. I bought a small a/c dial thermometer at the local auto parts store, placed in it the a/c vent and leave it in there to monitor temperature. I have a web page outlining most of what I have done and has some info on the fan replacement. I haven't done it yet.

Currently I have removed the splash shield from behind the passenger wheel and am tightening the bolts to the evaporator housing. They were loose and could have been a source of hot air into the system. In addition, I have some strip caulk and put a bead where the two halves come together and any where else it looks like heat could get in. When I caulked the inside of the fender it was difficult to get my arm in and I'm hoping to be able to seal it from the outside as well.

Every time I do something I seem to wring a degree or two out of the temp coming out of the vent.
 
Thanks for the info on the article JOE1975. I'm off to Auto Zone!! Will update my progress.
 
Something I wanted to try - an auxilliary fan IN the ducting

I have a buddy who's a VW freak - they have a nifty little fan that mounts in a duct that would appear to fit in one of the main air ducts of my vette. I keep meaning to get one before I even start thinking about putting in a Vintage A/C system.....

There is a pretty decent book out on vette a/c probs - but what I've heard here more or less covered it....
 
I went to the local NAPA parts store yesterday and bought a '95 vette blower motor with fan cage for $50. I made a template of the new motor's mounting surface and plan on pulling the old motor tomorrow and determine the dimensions of the spacer. The new motor does have 2 electrical plugs instead of one. I'll have to play with it to figure out what's what with those. I'll try and document the process and post as I progress. Hopefully this will project will be worthwhile. The duct mounted fans sounds interesting as well...
 
Have you looked at that little rubber tube to cool the motor?
 
Well, after much cursing and thrashing I finally have the '95 blower ready to go in tomorrow. I ended up making the spacer out of cabinet grade (7 ply) plywood. It's 1 & 1/8" thick. Getting everything lined up and centered was main concern. I put it in for a test run and did notice air actually "blowing" from the vents. How much better is yet to be determined on a road test.
I am now trying to figure out an easy way to route the cooling tube to the motor. The hole is on the opposite side from original and it is smaller than the original. I'm playing with grommets and flex tubing. Any suggestions?
I will post pics and comments.
Thanks for the input.
 
I was able to find the one for the 80's model cut it and added a piece of copper tubing can't even tell
 
Did you buy it new? What was your source. The local NAPA say they can't get one for the '95...GM only. Got it all put back together this morning. I made a tube using flexible tubing spliced into the old one. Had to use a 7/8" rubber grommet and silicone a small copper tubing connector to it in the motor, it should work fine. Hopefully, we'll give it a real test this weekend.
 
Everything came out from the top. Here is the order I used.
1. jack car up about 8" and put on stands, remove right wheel / tire.
2. remove a/c comp upper bolts & slip off belt.
3. I unpluged / moved all the wiring for the a/c clutch cycle switch / press shutdown, etc. just to free up more room.
4. remove overflow tank bolts & move the compressor toward the firewall. Snake the tank out from the top. You will probably have to unbolt the a/c sight glass/ pressure switch and gently move the line / around up to give you more room.
4. Once the tank is out, the motor is exposed but kind of hard to get at. unbolt 5 screws and unplug the wiring. It will come out through the same opening the overflow tank did.

I have some pics I will put together and post as soon as I can

We test drove last night and the wife commented that she could feel the difference in the force of the air out of the ducts. If I had to put a number on it... it boosted air flow about 20 - 30%.
 

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