Any A/C experts

[Learpilot]

Does your car have clutch on the radiator fan?If so,rev the engine and look at the fan,if it slows down considerably,that's probably your problem.
Its not cooling the condenser fast enough to condense what's coming out of the compressor,high pressure hot gas.The other consideration is if you have a receiver dryer unit instead of an accumulator,the dyer is partially restricted,with drying material.A lot of these dryers when they are wore out,will send the drying pellets which are inside a sack out to rest rest of the system and restrict the expansion valve,and possibly other components.
I used to see this happen all the time.What happens there is that the condensed hot liquid coming out of the condenser is filling the dryer faster than it can come out,causing a restriction.
Paisano

Thanks, I have a fixed flex fan that pulls a lot of air,  plus a 12" electric pusher fan on the condenser.
Every time I have opened the system I changed the dryer. I think the expansion valve may be the problem, but I am going to live with the current A/C then this fall or winter I plan to put a new complete A/C unit from Vintage Air.

[The Paisano]

If you have a restriction in these units,its usally going to show up as a frost ring around the component that's restricted.The rpm's have to be up a bit for to happen normally.If it is a real bad restriction,its not going to cool at all.Also,if you expansion valve is stuck open,the sight glass will have a lot of bubbbles,and it will shoe up that way regardless of the amount of freon that put into it,cause it floods the evapaorator.
Does this unit have a thermostatic control switch ?It looks wired in line to the copressor.Its shuts it off at a certain temp.You said that to went to 42
degrress.under the cover of the switch,there's usually 2 little screws,one times the compressor shut of time and the other regulates temp.In the old days we used to adjust the to run colder.Just make sure that you don't get real close to the freeze point,cause this will ice up the evaprator .  
Paisano

[Ed ke6bnl]

those are low suction pressures and you most likely have a low pressure cut out switch and as you increase rpm the suction pressure drops more and is probably going off on the low pressure sw. sound like low on gas. Ed

[muncie]

I tried 2 SA units, liked them so well that I tried a VA unit, liked it so well
that I am on my second Hot Rod Air unit. Wouldn't use anything else.
Just my .02

[Learpilot]

If you have a restriction in these units,its usally going to show up as a frost ring around the component that's restricted.The rpm's have to be up a bit for to happen normally.If it is a real bad restriction,its not going to cool at all.Also,if you expansion valve is stuck open,the sight glass will have a lot of bubbbles,and it will shoe up that way regardless of the amount of freon that put into it,cause it floods the evapaorator.
Does this unit have a thermostatic control switch ?It looks wired in line to the copressor.Its shuts it off at a certain temp.You said that to went to 42
degrress.under the cover of the switch,there's usually 2 little screws,one times the compressor shut of time and the other regulates temp.In the old days we used to adjust the to run colder.Just make sure that you don't get real close to the freeze point,cause this will ice up the evaprator .  
Paisano

I put a new thermostatic control switch ,because before I did it would turn off the compressor at 55 degrees. The new one cuts out at 40 degrees. I can live with this A/C unit this summer. In the fall/winter I plan to get a new Vintage a/c unit, complete with everything new. I am also going to redo my interior at the same time.
THANKS FOR YOUR INFO !!!  Rick

[papastoyss]

Go to www.jalopy journal, click on hamb board , look up member lobucrod, he sells the insulation I spoke of priviously. I found some at the swap meet at Asheville NC. yesterday & bought 2 rolls for my 40 coupe project. This is good stuff, far better than the foil/bubble wrap stuff that is commonly available. Also Bob Drake sells a insulating, sound deadning material similar to but thinner than Dynomat that is inexpensive to use. If you are going to strip & redo your interior I also highly recomend the Kool Kar ceramic insulation. Yes, I have all this stuff in my current ride & thats part of why we can't keep the A/C on high. My wife likes it, "happy wife,happy life"

[Learpilot]

Go to www.jalopy journal, click on hamb board , look up member lobucrod, he sells the insulation I spoke of priviously. I found some at the swap meet at Asheville NC. yesterday & bought 2 rolls for my 40 coupe project. This is good stuff, far better than the foil/bubble wrap stuff that is commonly available. Also Bob Drake sells a insulating, sound deadning material similar to but thinner than Dynomat that is inexpensive to use. If you are going to strip & redo your interior I also highly recomend the Kool Kar ceramic insulation. Yes, I have all this stuff in my current ride & thats part of why we can't keep the A/C on high. My wife likes it, "happy wife,happy life"

THANKS I will look him up for the insulation. I mostly go to car shows by myself ,but when she does go with me she does enjoy being comfortable.
I have found out that the money for a project is easyer if the CFO likes it. Some times it is hard to sell new shocks or other suspension stuff because there is no problem in the right seat.
You live near the spike tv speedway. Have you seen any of there project cars ?
Thanks , Rick