Nick Martorano

When I bought my 66 Coupe with factory AC, the compressor had been changed to the new style unit but they left all of the other stock components. I have now changed the evaporator, expansion valve, and dryer but still not blowing cold air. Only getting 69 degree temps. The system is supposed to take about 2.5 lbs of Freon but only taking in a 1/2 lb. Any idea of what the issue is? The only thing we have not changed is the compressor. Could that be the issue? Think we are going to change it today. Any help will be appreciated!

Thank you all in advance

65 Pro Vette

What did you do with the suction throttling valve? Did you pull a vacuum on the system? Where are you charging the system from?

Nick Martorano

Changed the suction valve to a new style R134 valve and system has been sucked via Snap On recovery machine. Charging low side from the new R134 POA Valve where it has a charge port and the high side from compressor manifold charge port.

Mike Geary

Don't understand how the system could be pulled down to 30"Hg and only take 8oz. The high side alone, if truly evacuated, should accept more than that.

What compressor do you have?

MIke

Nick Martorano

the Compressor is a Sanden that comes with a Billet Specialties Serpentine System. Took the compressor out and cleaned everything and put it back on and filled it with oil 2.4 oz. of new oil and now it took 2.4 lbs of Freon but is still only cooling to 69 degrees at the vents.

VetteJohn

I have a ’66 factory air coupe and have the same issue. Mine is also converted to 134a, Sanden style compressor and converted STV with temperature controlled switch. This system has never cooled the car down enough so that I can use the AC on really hot days. I’ve have to car to a couple of AC shops and no one seems to want to spent the time necessary to track down the problem. One thing I’ve noticed is I never get condensation out of the drain and I know the drain is not blocked. Beginning to think the temp co tolled switch is turning the compressor is off too soon.

Good luck with your problem, please keep us informed of how you make out.

Mike Geary

I've never messed with Sandens, but now that you are confident in the charge, I would next verify that you have high-side (discharge) pressure that is in spec. (if you haven't already) Of course, you will also have peeked at the drier sight glass to not see froth and hopefully see visible flow.

If all the above checks out then there's only one thing left that I can think of -- the expansion valve is not metering 134a into the evaporator.

It's either plugged on the inlet screen, or it's just NFG. Is it aftermarket? Curved bulb as original? Did you test it's operation before installation? If it bench tested good, then debris plugging the inlet screen is likely.

My thoughts, FWIW.

MIke

Nick Martorano

Thanks for all of the comments and help. I have a friend of mine working on it for me and will have him check everything again.

Powershift

I agree with Mike's comments/analysis.

If you have the right refrigerant charge, the correct discharge pressure, then about the only thing left is the expansion valve.

Suction pressure should be around 26-30 psig. Drier sight glass should be clear, but depending on your entire system configuration and charge it is possible to have some bubbles.............but they should not look like a lot air/inerts flowing thru the system. The compressor discharge pressure should also tell if the system has air............as discharge pressure will be very high.

Is the STV valve still in the system and operational?? This could causes problems if not operating correctly and holding the suction pressure above the 26-30 psig recommended value.

Larry

65air_coupe

I converted mine to the Sanden with serpentine belt system and converted STV to temp controlled and it works great. Hope you find your problem, can't beat good A/C these days.

Nick Martorano

Thank you! I sent my buddy all of the comments from all of you so I hope this helps sort it all out!

Nick Martorano

We are now thinking it is an Air Flow problem. Not enough air flow over the condenser. I have an aluminum Be Cool Radiator with a single electric fan but no shroud. Thinking maybe a double fan with shroud and possible another fan on the condenser to push air through. Comments?

Mike Geary

Is that theory based on having good compressor discharge pressure, but no evidence of liquid flow in the sight glass?

Nick Martorano

We came to this conclusion after we ran the AC with the electric fan disconnected and we ran cool water over the condenser and watched the pressures come down. We also were able to add another 1/2 lb of Freon while this was being done. We can see liquid flow in the sight glass.

Greg Hollowaty

Hi Nick,
Please be sure that your heater core is not active. hot water circulating through your heater core will KILL your cool air. The stock assembly includes a water cut off valve that is vacuum activated.

Nick Martorano

Good Idea! I will check that when I get back home today. I am thinking about removing the heater hoses anyway as I do not need heat here in South Florida! But if I can just shut the water off to the heater core.......that would be better.

Thanks Greg, I appreciate your help.

Nowhere Man

When you turn on the AC a vacuum switch on the top of the heater box closes the vacuum heater hose valve. So make sure all the hoses are in good shape and that the valve is working. You should be able to feel the small section of heater hose coming off the valve and see if the hose feels cooler then the hose leading to it.