Vintage Air Not Cooling Properly
 

Need some help with my VA Gen IV system in my 68 Camaro. Been fighting a cooling issue now for about 5 years (off and on) and I'm about ready to pull the entire system out and go another route. I've charged and re-charged the system probably 5 different times per VA's instructions. I've changed compressors to the SD7 Sanden. The issue I'm having is the vent temps will only get down to around 58-60F. AND as you start driving the car and everything normalizes, the vent temp increases to about 64F. The last attempt at troubleshooting, we hooked the gauges up and i rev'd the engine to 2000rpm and held it there. Low side was reading 5psi and high side was at 225psi. This was with the 24oz. of recommended freon. We added a few ounces and the pressures increased to 8-9 low side and 300 on the high side. Car is dripping water so there's nothing plugged or frozen up.

Called VA and they want me to "start from scratch" and asked me to drain the compressor oil and change the dryer. Also asked me to add back in 8 oz to the compressor but Sanden calls for 5oz so i'm already doubting the tech and because I've done this several times, I know it'll yield the same results.

Sooooo, all that said to see if someone on here with AC experience has any clue as to where to target my next troubleshooting efforts this weekend when I recharge the system.

Bad expansion valve? Blend door issue?

I've talked to several folks in my area with similar issues who have just given up on VA but it's too hot in South Louisiana to not have AC.

Much sympathy for you, I hate gremlins like this....especially when you know all the parts are there and new, and yet one of them is obviously bad.



Jeff-

It's been a long time since I've worked on AC, but those pressures seem way off. What are ideal pressures based on the conditions when you took the readings? I know when high side pressure is too high, the condensor can be partially plugged or your air flow is no sufficient.

Just throwing this out there as another thing to check... is the heater control valve flowing the correct way and wired correctly if I recall they have a directional arrow on their valves for recommended flow direction. Also think they used two different valves over the years depending on how old your system is. Hopefully you not getting a mix of hot water in the heater core at the same time the a/c is running through the evaporator core.

BB

From what I’ve been told 15-25psi on the low would be good, preferably on the higher side of that range.

Yeah I chased that rabbit a few years ago as well. VA sent me a new style valve. I’ve even installed a manual block valve ahead of that and closed it off.

I do automotive a/c full time up here in Canada and the pressures I typically see on production vehicles differ slightly from Vintage Air systems that I service a few dozen times a summer.5 psi is within VA specs for the low side and 225 on the high side makes me suspect your not getting rid of the heat in the condenser since the vent temp isn’t below 46 degrees. Try spraying some water on the condenser with the system on and if your vent temp drops like a rock in a few moments then you have verified your system can produce cold air. The fix could be as easy as a 2 speed fan that may pull more air then your current one or it might mean your condenser is under sized even though it was a kit made for your application.We have have lines run beside the exhaust manifolds and condensers mounted too far in front of the radiator with no seal so the fan just pulls air around the condenser instead of through it.Lots little things to look at ,but enough them and you have a problem. Just my two cents and I’m aware that there’s some really smart A/C guys on this site.Hopefully these few suggestions help

I'd start with your fans. Verified there blowing the correct direction and not reversed? SD7 has lower output than the 508, which is one of the reasons accessory drives have the overdriven crank pulley. Ive never experienced that issue with VA before. My only other thought is you have the blend door not programmed correctly. There is also 2 ECU's, one for factory air car and one for non air car. Have you verified you have the correct ECu for the installation? I know some people have had some issues, but Ive installed dozens and I think I only ran across one bad ECU.

I ended up receiving a PM from Shane @ Vintage Air and after discussing the issue with him, he's going to swap out the evaporator box due to an issue they had with a specific manufactured year range that mine falls in. Fingers crossed this fixes it but after talking through it with him, I'm hopeful. Just not looking forward to having to pull the unit out but if it'll produce cold air like it should, I'm up to the challenge.

To answer your original question, I did not verify if the ECU was correct or not. My car was a factory AC car and that's the system I ordered. I never got that far with VA's tech support to check that particular item. The fans are operating correctly.

I appreciate the feedback. I am planning to look at sealing up the areas to ensure I get as much air being pulled across the condenser as possible.