66 AC Odd Behavior Bordering on Wierd

[Neil C.]

OK Re. my 66 Roadster 4 Spd /427/390 with Factory C60/ with PS//but No Cold AIR from day I got it... AC never worked when I first had the car tho the AC Compressor clutch was functional... so I found a leak by the STV and then tightened and more R134 added that worked for a short time like 2 xs at 5 minutes each or so till Major Squealing..To be safe I had compressor rebuilt just and because with correct Compressor Dated cast and Date Frigidare it nonetheless needed the Clutch Wire terminal moved to 10 from 2 where it was placed incorrectly by previous compressor rebuilder anyhow,,,, even tho Squeal turned out to be 100 % from the BELT at Crank pulleys Correct Lover and upper 3 Groove AC Pulley
Note previous owner had a Clutch Cycling Switch Installed , but I do not know if the STV was converted to depend on that cycling or not with the available supposed UPGRADE aftermarket kit.. Possibly just someone added the Thermostat Cycling Switch... Nonetheless I removed that as I cant believe it worked properly and I tested in in Freezing Water and it would never open contact. I got it to Open only after I put in in the Freezer a while.
Anyhow LONG before any problem with evaporator etc over freezing from lack of cycling clutch on and off could even possibly occur HAD the STV been converted of which have no knowledge without dis assembly. I got Major Belt slippage and noise at First Belt that's not adjustable in first Grooves. Running all Correct Quanta Repop OEM style Wraps and sizes... noise was loud and compressor caused slippage at Crank to Water pump whenever AC was on with Clutch switch on Slippage actually caused the Fan not to move but slightly. Turn AC off and all was OK.... Mechanic thought belt was too loose but it runs fine as long as AC is off......so I worked on the car re other brake light issues and then after repairs re-checked all light functions at idle and decided to try AC again tonite after not trying AC for a week NOW and it WAS FINE.. AC Cranking out old air Clutch running Newly Re Built Compressor Ran a full 15 Minutes with NO SQUEAL...where as before Squeal was Immediate and debilitating the whole Belt system...WHAT Gives??? Maybe Temperature? Some slight amount of R 134 leakage causing less Pressure on Belt???? Was gonna have to try a new belt but now I am wondering.. Temperature at Previous AC Squealing Starts was Daytime 70-80 degrees and Garage Temp when NO SQUEALING tonite was 70 degrees..THOUGHTS?? only use AC at 70 Degrees at Nite or live with SQUEAL and Almost No Compressor turning AC due to slippage....THANKS for any HELP>>>>>>

[Harry S.]

Re: 66 AC Odd Behavior Bordering on Wierd

Neil,

Typically you will get belt noise when it is too loose, I would change the belt as you work through the prolem.

The expansion valve controls the Freon entering the evaporator. The bulb that is attached to the expansion valve that wraps around the top pipe exiting the evaporator box tells the expansion valve when to open and close. If the pipe is too cold the expansion valve closes so ice does not form. when the temp of the pipe warms the expansion valve opens and allows Freon to flow. If the expansion valve is stuck closed the car never gets cold. If it sticks occasionally it could cause your problem. The bulb is under that black gooey tape.

I've rebuilt my STV and I'm note sure you can alter the inside. All I have ever seen is an STV bypass. This means you replace your STV with another piece of hardware. This allows the system (compressor) to cycle differently.

Why not post some pictures of STV, expansion valve, etc.