Thanks so much for the responses. I already have an inline cutoff valve. Went out earlier tonight did find a couple of openings in the fire wall. Will let you guys know how things go. It appears I will have a busy weekend.
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Re: Hot Box 1977
I'll share with you one of the things I did while driving to the St Louis National some five years ago...maybe seven now. I got one of those indoor/outdoor thermometers and recorded the cabin temperature and A/C temperature in the duct. I used the external proble and shoved it down the throat of the duct where it blew cold. I believe the expected temp is like 43 or 44 degrees which my 78 A/C was blowing and this is early morning. The cabin temp stayed in the 60's until things heated up.
As the outside temp rose...so did the cabin temp until by mid-afternoon the cabin temp was nearly 90 and it was at that point it got extremely uncomfortable. The duct temp continued to blow cold but seems I recall it got up to maybe 48-50 degrees. But the cabin temp would continue to climb from it's base of mid-60's to the 90 range. My conclusion which is the same as many others is that in the later model years (78-82) the glass surface combined with the underbody exhaust/engine heat simply overwhelmed the ability of the A/C system to cool air and could not compensate for the mutliple sources of uncontrolled heat. But it did get better in later years as engineers discovered better ways to insulate the shark cars.
So you not only have the heat that penetrates from below and above but an A/C system that is inadequate. You'll do better than those with big blocks or THM400s. In 77, (actually 76) GM began to use the R3 radial compressor which is an improvement over the A6 axial used in early years.
Oh...this was probably July and I drove from the east coast (South Carolina) through the mountains and to St Louis so I did this over a couple of days.
I don't know if it was mentioned in the previous thread but an additional source of heat that penetrates the cabin is from the inside of the console...there is nothing there but metal to console. While you shop for parts, the insulation barrier material works well for the console area. Remove the console and cut the insulation to cover the metal of the transmission tunnel. Good luck and hope this helps.Tom Russo
78 SA NCRS 5 Star Bowtie78 Pace Car L82 M2100 MY/TR/Conv -
Re: Hot Box 1977
Tom I am a 70 coupe with factory air original owner and have driven my Corvette coast to coast and mainly in the southern states. It has the original A6 axial compressor. The car has SB with turbo 400. I can remember driving to Dallas from San Diego one time and having to wear a jacket in the car with the air on at night, to warm outside not to use the air, left the air on low blowing speed. Have lived in Dallas and the air was sufficient to cool the car. It still has R12, factory orignal carpeting, and has worn out one blower motor. I use the MAX air conditioning selection which circulates and cools the inside air. In the MAX position selection the water valve is closed which keeps hot engine coolant from circulating through the heater core which helps cooling. Not having all the glass of the later model coupes makes a difference for sure as well as having all fiberglass in the floor areas.Comment
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