Vintage Air / Sanden compressor troubles

[parsonsj]

I'm charging a brand new system. Vintage Air Gen IV, Sanden compressor, binary switch.

All new.

I evacuated the system (30" for two hours). Turn off vacuum pump, system holds vacuum without any needle movement at all for 2 hours. All is well.

Static pressures are 80-110psi (depending on ambient), and when I start the A/C, low side goes to 55psi, and high side goes way high. 350+, and the binary switch cycles it off. It drops to 250, cycles back on, and goes back to 350+. Cycles take 30s or so. Ambient temps are 80ish. Outlet air temp is 68*.

I've only charged the system with engine running for 5 minutes or so. Hardly at all. I can't believe I've got an overcharging condition. Yet those high side pressures are alarming.

Any ideas?

[Chevy Kid]

How much freon did you put in? Binary switch cuts compressor at 406psi.

[parsonsj]

Yes, I think the binary switch is cutting the compressor at 406 psi. My gauge set is probably just a bit off.

Scale says about a pound. Charge calls for a 1 lb 12 oz.

[dhutton]

Is the fan running? I usually point a box fan into the condenser when charging. It also makes it easier to charge if you place the freon can in warm water.

Don

[parsonsj]

Yes, the radiator fans were running. Condenser was very hot though. Maybe more fan would help.

[dhutton]

Windows rolled up and fan on max?

[parsonsj]

Yes, and yes.

[matty12]

how long does it take to cycle under high pressure? Is it immediate or takes a bit of time. Does pouring water over the condenser help at all? Wheres your high side port located? Can you feel any cold spots anywhere on the high side from compressor back to tx valve?

Could be overcharge or a blockage. If its a blockage it will be after your charge port

[KUL FIR CHICK N]

If you're running electric fans, you should be running a trinary switch. How are the fans triggered? Is this a new car? I've seen the fans running backwards before and that would cause this. Air in the system will cause high pressures as well. Assuming you're charging with a scale and gauges, when you switched from the vacuum pump to the bottle, did you purge the lines?

Ryan

[parsonsj]

how long does it take to cycle under high pressure? Is it immediate or takes a bit of time. Does pouring water over the condenser help at all? Wheres your high side port located? Can you feel any cold spots anywhere on the high side from compressor back to tx valve?

Could be overcharge or a blockage. If its a blockage it will be after your charge portIt's pretty immediate -- 30s or so. I'll try water/more fan, but the condenser is too hot to touch. I'll check for cold spots (a blockage, right?) The high side port is located on the fitting going into the condenser.

[parsonsj]

If you're running electric fans, you should be running a trinary switch. How are the fans triggered? Is this a new car? I've seen the fans running backwards before and that would cause this. Air in the system will cause high pressures as well. Assuming you're charging with a scale and gauges, when you switched from the vacuum pump to the bottle, did you purge the lines?No trinary switch. The fans are a whole separate thread -- I'm using the ECU along with an AC pressure sensor to manage the fans. https://www.pro-touring.com/threads/112506-PWM-radiator-fan-controller

Yes, this is a new car, and I'll check for the fans running backwards. Yes, I'm charging with a scale and gauges, and yes, I purged the line. The thing is, according to my scale, I've only got about half the charge in. (total is supposed to be 1 lb., 12 oz., but I have about 15 oz in). It's gotta be some kind of blockage, I think?

Is there any point to trying to get the rest of the charge in? Or should I evacuate/recover, and open the system now?

[parsonsj]

One other thing: I'm using a Sanden SD-7 compressor. It's tiny... could this be some sort of mis-matched component problem?

[dhutton]

I think you should add an external fan before you bail. Are your fans running max speed or something less?

The SD-7 compressor is lower displacement so it will not cool as well as the larger compressor. At least that is my understanding.

Don

[parsonsj]

I guess the other thing that's important is that there is an intercooler between the radiator and the condenser.

Yes, the fans are running max speed (discrete mode), and I'm turning them on manually. I'll get another fan and some water on condenser... and see if that drives down the high side pressure.

[parsonsj]

Uh... never mind.

I think I figured it out. :hand: I never removed the cardboard protection from the intercooler core. I put all this together over a year ago, sent it off to paint, then bolted it in.

I had no airflow at all through the condenser.

Anyway, thanks to all for banging on "fans, fans, fans" until I got my brain working again.

[dhutton]

Uh... never mind.

I think I figured it out. :hand: I never removed the cardboard protection from the intercooler core. I put all this together over a year ago, sent it off to paint, then bolted it in.

I had no airflow at all through the condenser.

Anyway, thanks to all for banging on "fans, fans, fans" until I got my brain working again.

Good to know I am not the only one doing stuff like that.... :lmao:

Don

[parsonsj]

Good to know I am not the only one doing stuff like that

LOL! I know!

I'm just glad I listened to you to add more fan before pulling the whole system apart.

[dontlifttoshift]

Made my Monday, thanks!!

Let us know what the gauges read now, and the thermometer in the vents.

[parsonsj]

I got 52* air, 35/320 on gauges, 85* ambient, 80% humidity.

I think I'll be happy with that. Thoughts?

[KUL FIR CHICK N]

That'll do it, and that's why I asked if it was a new car. Glad it was something simple.

Closed loop fan control via pressure transducer is the hot setup...we're running a similar setup on the "Will Chill" '36 Ford.

On Sanden compressors, SD7 just means it's a 7 cylinder compressor. They make all different sizes of SD7's. If you're talking about the SD7b10 that we originally introduced on our Front Runners, it's a 100cc compressor and yes, it is smaller than the more common "508" style. The SD7b10 is good for around 14-17k BTU, which is a perfect match for most aftermarket systems. A larger compressor will perform better at idle, but will cycle more often at speed and on the highway. On Vintage Air Front Runner systems, we overdrive the SD7b10 more than we do the 508 in order to offset the displacement difference.

Ryan Zwicker
Director of Engineering
Vintage Air, Inc.

[KUL FIR CHICK N]

I got 52* air, 35/320 on gauges, 85* ambient, 80% humidity.

I think I'll be happy with that. Thoughts?

With the windows up, 1500-1800 engine rpm, blower on high, I'd expect the high side to be around 250-275, low side will pull down to around 17-20 and the compressor will then cycle. Vent temp should pull down to around 40 before the compressor cycles (after sufficient cool-down of the cabin).

At 320 on the high side, you aren't getting enough air flow across the condenser. You might want to seal any gaps between the condenser/intercooler/radiator that would allow air to bypass your heat exchangers. Same with the fans, you need to ensure all of the air that the fans are moving is coming through the radiator and not through leaks in the shroud.

[dontlifttoshift]

Put a box fan in front of the condenser and see if it gets better, in the vents and on your pressure readings. I would like to see high side come down a lot.

[KUL FIR CHICK N]

Put a box fan in front of the condenser and see if it gets better, in the vents and on your pressure readings. I would like to see high side come down a lot.

Yes, the high side is too high, especially at only 700RPM.

[parsonsj]

OK, I fussed at it some more today. I recovered, vacuumed, and re-charged, using a buddy's A/C scale. I went a bit less on the charge weight given my mini-compressor.

Numbers: (with windows open -- there is no windshield in the car yet; I should have mentioned that before :hand: ) 44* vent air, 25/175, 80 ambient, 85% humidity, 700 rpm. Condenser was only warm to the touch. Fans had no problem keeping temps down.

It seems obvious that I was over-charged earlier. Thanks for all the help guys!! I really appreciate it.

Next question: should I worry about compressor oil levels, since I vacuumed it twice?

[dontlifttoshift]

That's more like it. I wouldn't worry about the oil.

[parsonsj]

That's more like it. I wouldn't worry about the oil.Thanks Donny!

That'll do it, and that's why I asked if it was a new car. Glad it was something simple.

Closed loop fan control via pressure transducer is the hot setup...we're running a similar setup on the "Will Chill" '36 Ford.

On Sanden compressors, SD7 just means it's a 7 cylinder compressor. They make all different sizes of SD7's. If you're talking about the SD7b10 that we originally introduced on our Front Runners, it's a 100cc compressor and yes, it is smaller than the more common "508" style. The SD7b10 is good for around 14-17k BTU, which is a perfect match for most aftermarket systems. A larger compressor will perform better at idle, but will cycle more often at speed and on the highway. On Vintage Air Front Runner systems, we overdrive the SD7b10 more than we do the 508 in order to offset the displacement difference.

Ryan Zwicker
Director of Engineering
Vintage Air, Inc.Ryan, thanks for removing your invisibility cloak. :) The SD7 I'm using is the teeny little one sold by Concept1 for use with an LS9 in a DSE subframe.

I'm still struggling with the fan control. Rick Love told me not to do it, and to stay with discrete fans. Sometimes I don't listen. :) I got a new ECM today that was supposed to work, but it had an OS/VIN mismatch, so I've got another one coming.

Question: what would you recommend about fan percentages vs pressure?

115809

[dhutton]

Rick Love told me not to do it, and to stay with discrete fans. Sometimes I don't listen. :)



LOL, must be an engineer...

Don

[KUL FIR CHICK N]

Thanks Donny!
Ryan, thanks for removing your invisibility cloak. :) The SD7 I'm using is the teeny little one sold by Concept1 for use with an LS9 in a DSE subframe.

I'm still struggling with the fan control. Rick Love told me not to do it, and to stay with discrete fans. Sometimes I don't listen. :) I got a new ECM today that was supposed to work, but it had an OS/VIN mismatch, so I've got another one coming.

Question: what would you recommend about fan percentages vs pressure?

115809

That looks pretty good to me. If anything, I'd go 100% at anything over 300psi if it'll let you. Would be good to monitor pressure while cruising on the highway and tune the bottom end of the curve to that.

Your compressor is an SD7b10, or a knock-off equivalent. Not sure if C1 is using Sandens or "Sanden style" but, either way, it's a 100cc/rev.

Ryan