Vintage Air users - share your vent temps? I need mine cooler!

[GoodysGotaCuda]

I been working with a Vintage Air in my Cuda and it cools, what I consider, adequately. I'd like to see if there may be some cooler air left on the table that I need to unveil. Insulating lines, changing the charge, bigger condenser, etc.

This afternoon was about 91°F in Texas and fairly humid. After about thirty mins of driving, my lowest vent temp touched 42° and I averaged 46-47°. I'd really be happy if I could get another 3-5° out of it, somehow. It's cooling, but I haul two little kids in my car and would like more capacity.

Can you share some vent/ambient temps?
any tricks you have done to get yours cooler?

[dontlifttoshift]

What do your gauges read at those temps?

Dropping 45* in a 50 year old car is nothing to sneeze at. I usually get under 40* in the center vent regardless of ambient but I typically don't see a lot of 90* plus up here this close to the lake.

I have never stuck my thermometer in a late model vent, what's the X1 blow?

[GoodysGotaCuda]

What do your gauges read at those temps?

Dropping 45* in a 50 year old car is nothing to sneeze at. I usually get under 40* in the center vent regardless of ambient but I typically don't see a lot of 90* plus up here this close to the lake.

I have never stuck my thermometer in a late model vent, what's the X1 blow?


Off of the top of my head, about 325psi/35psi at 1500rpm. From what I was reading, the vintage air may want to run at sub 15psi on the low side. I’ll try to pull some more charge out of it and see if things improve.

[ULTM8Z]

Yeah I think they're the same as Classic Auto Air in terms of pressures.

They say low side of 6 to 22. High side is 160 to 250...rule of thumb is 2x ambient temp + 15-20%.

I'm running CAA and getting mid to high 30s out the vents.

[dontlifttoshift]

If those numbers are real, you need to get that High side down a lot.

It does sound like you are over charge. 1.8 pounds. That's all it needs. I would evacuate the whole system and start from scratch with the freon so you know exactly how much is in there.

Which compressor are you running?

[ULTM8Z]

I think they generally want 24 oz of refrigerant. I just went by that and got the correct pressures by default.

[Z06vet]

I got the best results with 1.7lbs. It stayed a bit colder, and would never cycle off on long trips

[GoodysGotaCuda]

I've pulled some refrigerant and will sneak up on the proper pressures. I haven't had any luck charging to weight when not using a real a/c machine, I'll watch the pressures.


Using a saden Hemi compressor

[Twentyover]

May also want to look at how much fan you have. When I was working for an OEM, we had an A/C non-conformance- the A/C would not meet outlet temperature requirements. Why? the BCM was shutting down the compressor to prevent an engine overheat. Added another 60 watts of engine cooling fan and the test was successfully completed.

More air across the condenser will also lower discharge pressures

[GoodysGotaCuda]

Thanks, I got my high speed fans wired up and it seems to be doing slightly better. I am still messing with the charge amount, I seem to get better cooling at idle than I do at higher rpm. Hopefully I'll have some better results when I get back to it later in the week.

[btmatt]

If you have access to a vacuum pump and gauges ( i usually rent from autozone), i would evacuate the system, hold, check for leaks, and recharge the proper amount based upon either weight/volume. in my experience, pulling a good vacuum and making sure the system holds is critical to a properly operating system.

[GoodysGotaCuda]

I’ve been able to net a pretty substantial drop in temps by playing with the evap temp probe positioning.

Thus far, with no refrigerant changes I am getting a 6-11° vent temp drop from doing only that, depending on the conditions. In some instances I have hit high 20°F temps, which I know will freeze, eventually but over a 20min, closed window commute on a 78° morning it did not have a hint of freezing.

I think it’s safe for me to say that the vintage air temp probe is a bit conservative on its compressor kick out temperature. Will follow up on how it does during the 100°F drive home today.

[dhutton]

What are your current pressures with that mod? At what rpm?

Don

[GoodysGotaCuda]

What are your current pressures with that mod? At what rpm?

Don

Off the top of my head, 250psi/30psi at 1100. I played with the charge in either direction and always kicked out at 42°. 42 isn’t bad, but it’s not mid 30s when it’s 100° out.

The “mod” was just pulling the thermistor probe out of the core about 1/2”. More cabin air passes by it and therefore it takes more cold in the evap for it to cycle. Took no tools and can be accessed by just looking by the blower motor.

$0, minimal effort and very good results so far. I like those kind of mods.

[KUL FIR CHICK N]

What a cool build! Sorry I'm late getting to this party, but I have some thoughts on this.

To start, you should work to get your vent temperatures down to 40-42, but not any lower. The system in your car is designed to turn off the compressor when the thermistor probe senses 34-degree coil surface temperature. At this coil temperature, with everything else set-up properly in the car, you should be able to get consistent vent temps in the low 40's after a short "pull down" period. The thermistor probe has been carefully positioned through extensive wind tunnel testing and the cycling algorithm has been developed to provide maximum performance without freezing the evaporator. Attempting to defeat this is sure to lead to frustration. You'll ultimately be much happier with the thermistor in the factory designed location. We understand the desire to tweak settings and modify components for higher or different performance, (after all, that’s hot-rodding!) but the thermistor settings and algorithm aren’t particularly conservative. Once ice begins to form on the coil, it’s difficult to detect until you have a run-away situation. Think of it as detonation…..you don’t want to go there.

Your efforts will be much more rewarded by focusing on the rest of the set-up.

Starting in the front of the car, make sure you have good air flow through the condenser whenever the system is running and that the air flowing through the condenser is fresh and not being reintroduced from behind the radiator. Make sure your fan package is well sealed to the radiator core and covers the entire effective area and that the air leaving the fans exits the engine bay only to the rear. Its not uncommon for poorly fitted or missing panels to allow hot engine bay air out through the front of the core support (or under/over), which is then pulled back through the condenser and radiator. This will cause high head pressures, engine temperatures, and KILL performance.

Your system is designed to run 1.8# of 134a refrigerant. If everything is set-up properly, you will have no problems maintaining <275 psi head pressure. There is a small amount of safety factor built in to the 1.8# charge determination and you could get away with as low as 1.5#, but any lower will adversely affect performance. It's unlikely you'll see a measurable performance difference between 1.5 and 1.8# unless you have condenser air flow issues. You should never attempt to adjust the charge without a quality charging station. I assume you properly evacuated the system prior to charging. If not, you need to start over, ideally with a charging station.

At the firewall and underbody, make sure there are no air leaks. Pay attention to the shifter boot, brake and throttle pass-throughs, fresh air vents and any unused holes. Make sure that's all sealed-up. I read some of your build thread and noticed that you've applied Lizard Skin and bed liner. That's good stuff and the right move. The most effective place to put it is on the firewall, all the way up, and above the exhaust, all the way back. Additional insulation beyond the Lizard Skin isn't a bad idea either. If you haven’t insulated the roof, it’s worthwhile.

Inside, make sure all the duct hoses are properly attached to the distribution plenum and the louvers and that the hoses are pulled tight and not kinked or crushed. It’s common for people to leave excess hose draping which leads to significant air flow loss. Inspect the door and window seals for damage and proper fit and be sure that the windows are adjusted to seal well. Note that even the trunk lid seal is important as the low-pressure area at the back of the car will draw air out the back of the cabin through leaky seals. Conditioned air pulled out the back will be replaced by hot air leaking in through the front.

If you’re OK with tinting the windows, choose a quality ceramic tint. You can even get ceramic tint that appears almost completely clear but provides 40+% IR blocking. With a black interior, quality tint makes a huge difference.

Hope this helps. Feel free to contact me via PM if you have any questions. We’re all car guys at Vintage Air. We appreciate your business and support and we’re here to help.

Ryan Zwicker
Vintage Air, Inc.

[GoodysGotaCuda]

Ryan, I really appreciate your presence here on the forum, it's nice to see Vintage Air poking around at what their customers may be up to.


What a cool build! Sorry I'm late getting to this party, but I have some thoughts on this.

To start, you should work to get your vent temperatures down to 40-42, but not any lower. The system in your car is designed to turn off the compressor when the thermistor probe senses 34-degree coil surface temperature. At this coil temperature, with everything else set-up properly in the car, you should be able to get consistent vent temps in the low 40's after a short "pull down" period. The thermistor probe has been carefully positioned through extensive wind tunnel testing and the cycling algorithm has been developed to provide maximum performance without freezing the evaporator. Attempting to defeat this is sure to lead to frustration. You'll ultimately be much happier with the thermistor in the factory designed location. We understand the desire to tweak settings and modify components for higher or different performance, (after all, that’s hot-rodding!) but the thermistor settings and algorithm aren’t particularly conservative. Once ice begins to form on the coil, it’s difficult to detect until you have a run-away situation. Think of it as detonation…..you don’t want to go there.


Are you stating that with 40-42° vent temperatures that I would expect to have a 34° coil temperature? That sort of temp increase with the relatively short ducting is not what I was expecting, but could certainly explain a few things a little more for me. The hot rodder in me sought out for more, I haul my 4 month old and 2.5 year old in the 'Cuda very often and naturally things get pretty warm in Texas. A consistent few degree drop makes a huge difference, that said, I wasn't feeling satisfied with the Vintage Air system only getting down to 42°F. While in the HVAC technician textbook I understand it is sufficient given the high ambient temperature, to today's standards, it's a high vent temperature.




Your efforts will be much more rewarded by focusing on the rest of the set-up.

Starting in the front of the car, make sure you have good air flow through the condenser whenever the system is running and that the air flowing through the condenser is fresh and not being reintroduced from behind the radiator. Make sure your fan package is well sealed to the radiator core and covers the entire effective area and that the air leaving the fans exits the engine bay only to the rear. Its not uncommon for poorly fitted or missing panels to allow hot engine bay air out through the front of the core support (or under/over), which is then pulled back through the condenser and radiator. This will cause high head pressures, engine temperatures, and KILL performance.

I feel that I have excellent flow over the condenser, the only thing I can think to change is adding a foam strip between it and the radiator to ensure as much fan air goes through it as possible. I am running dual V6 Ford Contour fans [high speed for a/c] and they move a TON of air and are properly shrouded onto the radiator.


Your system is designed to run 1.8# of 134a refrigerant. If everything is set-up properly, you will have no problems maintaining <275 psi head pressure. There is a small amount of safety factor built in to the 1.8# charge determination and you could get away with as low as 1.5#, but any lower will adversely affect performance. It's unlikely you'll see a measurable performance difference between 1.5 and 1.8# unless you have condenser air flow issues. You should never attempt to adjust the charge without a quality charging station. I assume you properly evacuated the system prior to charging. If not, you need to start over, ideally with a charging station.

Does the amount of refrigerant required vary based on the application? I question this because I have more lines and a different compressor than the cookie-cutter e-body Vintage Air kit. The compressor is off of a new Hemi and mounted low on the driver's side of the engine. The high side line routes low around the lower radiator support and up to the drier/condenser, then continues through the passenger inner fender to the evaporator. The low side line runs behind the engine, past the steering box and back into the compressor.

Would there be any benefit in further insulating some of my pressure hoses?


At the firewall and underbody, make sure there are no air leaks. Pay attention to the shifter boot, brake and throttle pass-throughs, fresh air vents and any unused holes. Make sure that's all sealed-up. I read some of your build thread and noticed that you've applied Lizard Skin and bed liner. That's good stuff and the right move. The most effective place to put it is on the firewall, all the way up, and above the exhaust, all the way back. Additional insulation beyond the Lizard Skin isn't a bad idea either. If you haven’t insulated the roof, it’s worthwhile.

Inside, make sure all the duct hoses are properly attached to the distribution plenum and the louvers and that the hoses are pulled tight and not kinked or crushed. It’s common for people to leave excess hose draping which leads to significant air flow loss. Inspect the door and window seals for damage and proper fit and be sure that the windows are adjusted to seal well. Note that even the trunk lid seal is important as the low-pressure area at the back of the car will draw air out the back of the cabin through leaky seals. Conditioned air pulled out the back will be replaced by hot air leaking in through the front.

If you’re OK with tinting the windows, choose a quality ceramic tint. You can even get ceramic tint that appears almost completely clear but provides 40+% IR blocking. With a black interior, quality tint makes a huge difference.

The cabin is as sealed up as I can get it right now, the side windows do leak some air. The roof, lower firewall and entire floor of the car is ceramic lizard skin coated. I believe you are onto something with the clear ceramic tint, I had not heard of that before and I know it is somewhat of a limitation. The glass does let in a large amount of radiant heat.

Thanks for your time and feedback!

[MAGONSTERZ68]

same here pulled system down to replace failed trinay and heater servo valve. vac'd down, charge with recommended 28OZ and now operating pressures are through the roof, bled out low side to get pres. down to recommended 240-250 and 16-22 and it would not cool past 80*, going to call VA monday to get recommendations.

[rickpaw]

Would there be any benefit in further insulating some of my pressure hoses?



same here pulled system down to replace failed trinay and heater servo valve. vac'd down, charge with recommended 28OZ and now operating pressures are through the roof, bled out low side to get pres. down to recommended 240-250 and 16-22 and it would not cool past 80*, going to call VA monday to get recommendations.

Just to follow up on this, did you guys get your issues worked out?

I just did my AC system yesterday, after switching out to a mini compressor/EZ clip AC lines and fittings. I pulled a vacuum and put in over 2 cans of refrigerants. I don't have a scale so I watched the pressures - at 95deg ambient temp, low side was 20/high side was just under 225. My center vent temp was in 38-41 deg range with an infrared thermometer.

I did notice the low pressure side hose was "sweating". Should I insulate that line with home AC insulating tape?

[GoodysGotaCuda]

Just to follow up on this, did you guys get your issues worked out?

I just did my AC system yesterday, after switching out to a mini compressor/EZ clip AC lines and fittings. I pulled a vacuum and put in over 2 cans of refrigerants. I don't have a scale so I watched the pressures - at 95deg ambient temp, low side was 20/high side was just under 225. My center vent temp was in 38-41 deg range with an infrared thermometer.

I did notice the low pressure side hose was "sweating". Should I insulate that line with home AC insulating tape?


Sweating is fine. I couldn't get below 42* until i slightly moved the evap temp probe. Naturally that is not advised from VA, but it made it work substantially better.

[MAGONSTERZ68]

Went all back together and lame 62 degrees no matter what i do, opened post on forum listing issues and attempts or fix....no luck thus far :/

[dhutton]

Went all back together and lame 62 degrees no matter what i do, opened post on forum listing issues and attempts or fix....no luck thus far :/

Are you testing with the windows rolled up? At idle or something higher like 2000 rpm?

Don

[MAGONSTERZ68]

tinted windows are up and idle at 1800 rpm

[ULTM8Z]

when you recharge it are you using pure refrigerant or is it mixed with additional oil? also may want to disconnect the heater lines temporarily. maybe the diverter door is malfunctioning and you're getting warm air mixed in.

[MAGONSTERZ68]

68 Camaro GenIV sure fit system
Using 3 knob billit rotary variable blend / speed/ temp controller and not the original with mods.(does it have to be calibrated to system?)
SD5 compressor
Car utilizes dual electric fans 3000 cfm with trinary switch keeps car steady at 205 in 100 plus degree weather.
Inline aluminum through firewall bulkhead with extended lines routed through fender
Radiator to core support is foam sealed and pulls hard through closely spaced radiator / condenser / trans cooler

1st attempt:
Charged system on 98 degree ambient temperature day
Evacuated with zero problems 1 hr., held vac no prob 1 hr.
Used digital scale to load loaded 1lb 12oz as per instructions.
Charge was loaded with car at 1800 rpm (to simulate cruising speed) 3.42 gears with 26" tall rear tires
Low side was 30, high side was 275, and center vent temp was 62 degrees
line on compressor was cold and sweaty

Second attempt:
Evacuated 45 min, held vac 45 min
Loaded freon until gauges read 12 to 15 psi on the low and 175 to 200 psi on the high at 1800 rpm same 95 degree ambient temps
Line was NOT cold or sweaty
center vent temps never dropped below 80 degree.

Third attempt:
utilizing second attempt continued to load feaon utilizing gauges read 30 psi on low and 275 on the high again
temps dropped back down to 62 degrees, line was cold and sweaty.

At one point i pinched off the hot water in line to the core to verify i was not getting hot water bleed by into case, no change in temps whatsoever.
On all three tests i sprayed water at condenser, head pressure would drop and low side would follow suit, it would cycle out and recover to high low as before.

[GoodysGotaCuda]

Went all back together and lame 62 degrees no matter what i do, opened post on forum listing issues and attempts or fix....no luck thus far :/

What are the pressures?

[MAGONSTERZ68]

Used autozone freon stuff with oil and dye mixed in with it if that is of any difference.
Thinking i might vack the system flush drier and condenser and reload with JUST freon with zero additives such as dye, oil or seal conditioner.

- - - Updated - - -

1st attempt:
Charged system on 98 degree ambient temperature day
Evacuated with zero problems 1 hr., held vac no prob 1 hr.
Used digital scale to load loaded 1lb 12oz as per instructions.
Charge was loaded with car at 1800 rpm (to simulate cruising speed) 3.42 gears with 26" tall rear tires
Low side was 30, high side was 275, and center vent temp was 62 degrees
line on compressor was cold and sweaty

Second attempt:
Evacuated 45 min, held vac 45 min
Loaded freon until gauges read 12 to 15 psi on the low and 175 to 200 psi on the high at 1800 rpm same 95 degree ambient temps
Line was NOT cold or sweaty
center vent temps never dropped below 80 degree.

Third attempt:
utilizing second attempt continued to load feaon utilizing gauges read 30 psi on low and 275 on the high again
temps dropped back down to 62 degrees, line was cold and sweaty.

[dhutton]

I use the R134A with dye and it works fine.

Don

[GoodysGotaCuda]

Used autozone freon stuff with oil and dye mixed in with it if that is of any difference.
Thinking i might vack the system flush drier and condenser and reload with JUST freon with zero additives such as dye, oil or seal conditioner.

- - - Updated - - -

1st attempt:
Charged system on 98 degree ambient temperature day
Evacuated with zero problems 1 hr., held vac no prob 1 hr.
Used digital scale to load loaded 1lb 12oz as per instructions.
Charge was loaded with car at 1800 rpm (to simulate cruising speed) 3.42 gears with 26" tall rear tires
Low side was 30, high side was 275, and center vent temp was 62 degrees
line on compressor was cold and sweaty

Second attempt:
Evacuated 45 min, held vac 45 min
Loaded freon until gauges read 12 to 15 psi on the low and 175 to 200 psi on the high at 1800 rpm same 95 degree ambient temps
Line was NOT cold or sweaty
center vent temps never dropped below 80 degree.

Third attempt:
utilizing second attempt continued to load feaon utilizing gauges read 30 psi on low and 275 on the high again
temps dropped back down to 62 degrees, line was cold and sweaty.

Have you removed coolant from the heater core by blocking off the hoses? The second attempt pressures look right to me assuming you have adequate airflow across the condenser.

[ULTM8Z]

have you checked the voltage at the compressor clutch?

[MAGONSTERZ68]

have you checked the voltage at the compressor clutch?

yes full voltage, as well as correct gap, clutch is fully engaging and not slipping.

- - - Updated - - -


Have you removed coolant from the heater core by blocking off the hoses? The second attempt pressures look right to me assuming you have adequate airflow across the condenser.

think im going to disconnect the water heater lines for now see if makes a diff.

[MAGONSTERZ68]

so after all this time later, good friend acquired a legit a/c machine. We pulled it down, held vac, loaded 1.8 of freon. At idle and 80 deg ambient temps, at sea level, center vent cooled down to 48-50. Called it good, 229 on the high side and 30 on the low. I have not driven much lately to check on road temps would really like to dip into the mid 40's if feasible with either adding or removing freon.