Automotive Air Conditioning Information Forum

Hello All, this is my first post on Auto AC. I'm excited to be here, seems like a lot of intelligent folks on the boards.

My vehicle is a 1993 Dodge B-150 Van. I am located in Brooklyn, NYC. I have had my van for over 10 years and it has a lot of sentimental value. I paid only $1500 for it when I got it and have pu on about 120,000 miles since it became the owner. I have done an engine and transmission swap on it, a rear end swap, a suspension rebuild (twice) and basically I have a 350-series drivetrain and suspension on a 150-series, short wheelbase van.



It's a fun vehicle but it was built without air conditioning—it only had heat from the factory. This has been okay for 10 years, but I finally decided to try and put air in this bad boy.

I thought about buying a junked van with AC and transplanting all the stuff over, but thought it too big of a task as I live in Brooklyn, NYC, and having a junk vehicle around is hard to do in urban areas. I also found that AC vans have a strange grate on the firewall on the passenger side that seems to be part of the sheetmetal. Plus, I have a lot of custom work going on under my dash (wiring, and amp, other custom things) and the entire dash would have to be replaced with one with holes for the vents. So, I decided to go with an aftermarket system.

I bought an evap unit from a company called ColdMaster https://coldmasterinc.com/product-categ ... oning-kit/ in Florida. The evap unit was advertised as being good for commuter vans so I figured it would keep me icy cold. It has a rating of 22,220 BTU which I thought would be more than enough.

The evap unit:
https://coldmasterinc.com/product/unive ... v-223-100/



Under the hood, I was able to source brackets and a compressor from a junked van. I did install a new compressor, which is a Sanden 4785 repop. CORRECTION! It's a Denso 471-7031 New Compressor. NOT a Sanden repop.
I made all custom hoses, and source my parts (fittings, drier, binary switch, fan, condenser) from ColdHose.

For a condenser, I used a 16x28 parallel flow unit.

For a fan, I used a 14" model.

I mounted the Evap unit in the center of the van, on the ceiling above the windshield. This may seem like and odd choice, but I've seen a lot of custom vans with really cool overhead consoles in this area and it doesn't really block visible much at all.

Wish I had a better photo:


I built a custom console to go around the unit and hide all the hoses and wires, and threw a couple speakers up there as well. The console is a 3-piece unit: 2 speaker boxes and on box to cover the evap unit.

All hoses are run through the A pillars. The smartest part is the way I deal with condensation. I mounted a peristaltic pump in the speaker box, which routes water down through a hose in the A pillar as well.

Once I got the system all buttoned up (took me a LONG time to complete!) I vacuumed down and charged up the system myself. I rented gauges and a vacuum pump from Autozone and used about 5 (maybe?) cans of r134a.

Unfortunately I am disappointed! I can only get my vent temp down to about 58* on an 80* day.

I took it to 2 different AC shops and they all told me that the unit was too small for the inside of my van. Okay, that makes sense that it would never cool down the interior of my van. But should the vent temp at least be lower? I mean, I have a convertible, and even when the top is down the vents seem pretty damn cold.

Right now I am planning to add another, larger unit in the rear on the van. I have one that is rated at 35,000 BTU. Curious what you all think about this plan, also curious if I am suppose to run the evap units in parallel or in sequence. Thanks in advance!

GottaBeCold88 wrote: ↑Thu Jul 14, 2022 3:03 pm Once I got the system all buttoned up (took me a LONG time to complete!) I vacuumed down and charged up the system myself. I rented gauges and a vacuum pump from Autozone and used about 5 (maybe?) cans of r134a.
Unfortunately I am disappointed! I can only get my vent temp down to about 58* on an 80* day.

At first glance, +/-five cans sounds like a lot of refrigerant for that system. It might actually be overcharged. What pressures did you record after charging it?

Did the cans contain pure refrigerant, or did they have any sealer and/or other additives in them?

With a correct charge into a well-held vacuum, a system free of all air and moisture, and efficient compressing/condensing/evaporating, you should be seeing vent temps much lower than 58°F at an ambient of only 80°F.

A van requires a lot of cooling, so the addition of a rear set-up will certainly help. Others on this Forum might wish to comment further.

Thanks John. I'm worried I may be overcharged as well. I think I might want to evacuate and start fresh.

Question—when you have the refrigerant evacuated, does it take all the oil out with it as well? I'm also a little unsure if I have enough oil in it. I'd like to start fresh with a more measured approach to both oil and refrigerant.

Can you give us more details? Hose sizes you ran to the evap unit? Drive ratio crank to compressor pulley? How did you determine how much refrigerant to charge? What is the expansion device? Is there an accumulator or a receiver?

A second evap unit will help total cooling power, but the air coming from both will be warmer than you have now. It will be a lot of interior airflow and noise with slightly cool air. People usually prefer colder air because there will be not so much fan noise to stay comfortable. If you go that way, plumb them in parallel.

GottaBeCold88 wrote: ↑Fri Jul 15, 2022 6:21 am I'm worried I may be overcharged as well. I think I might want to evacuate and start fresh. Question—when you have the refrigerant evacuated, does it take all the oil out with it as well? I'm also a little unsure if I have enough oil in it. I'd like to start fresh with a more measured approach to both oil and refrigerant.

I'm not an expert on aftermarket systems, but I do know that an original factory-installed A/C system for your '93 called for 44 ounces net weight of R-12 and 7.25 fluid ounces of Mineral Oil without rear A/C. With rear A/C, the specs are 65 ounces of R-12 and 9 ounces of Mineral Oil.

You've done a lot of custom work on your van, so these specs might or might not be appropriate for your aftermarket R-134a system with different components and hose lengths. But they might give you a "ballpark" about where to start.

As you can see, the amount of refrigerant that you charged into your front-only system tracks more closely with an original van having both front and rear A/C, presuming that you used five 12-ounce cans. So I'm still leaning toward the possibility of an overcharge as the reason for your elevated vent temperatures. A corollary to that is your Sanden copy might not have enough displacement to give you the performance you expect.

If you have a shop recover the system, some oil usually will come out, and it will accumulate in a graduated container on the side of the recovery machine. This lets you or the shop know exactly how much to add back in when you recharge it. Evacuating a system prior to recharging doesn't normally remove any oil.

How much and what type of oil does the new compressor call for?

So how about some pressures?

Engine RPM above 1500, evaporator fan on highest speed. Hold that for 90 seconds to stabilize and read the pressures while the engine RPM is above 1500.

Dragging the hot air from the top edge of the windshield across the evaporator is not going to provide the best vent temps anyway. Might want to consider relocating the evaporator behind the driver's head and blowing forward toward the front seats.

DetroitAC wrote: ↑Fri Jul 15, 2022 6:34 am Can you give us more details? Hose sizes you ran to the evap unit? Drive ratio crank to compressor pulley? How did you determine how much refrigerant to charge? What is the expansion device? Is there an accumulator or a receiver?

A second evap unit will help total cooling power, but the air coming from both will be warmer than you have now. It will be a lot of interior airflow and noise with slightly cool air. People usually prefer colder air because there will be not so much fan noise to stay comfortable. If you go that way, plumb them in parallel.

To answer your questions:

Hose sizes you ran to the evap unit? - #6 and #10 reduced barrier. See my plumbing diagram below:



Drive ratio crank to compressor pulley? Unsure. How do I find this?

How did you determine how much refrigerant to charge? I just went off the gauges. This was my first time doing this. I think I way overcharged it as the gauges weren't changing as I filled. Suddenly the gauges spiked and the system started shaking. Then I shut down the motor, evacuated a significant amount of refrigerant (and oil with it) but unsure how much. I got a little freaked out. Gauges read what I think is normal now.

What is the expansion device? There is an expansion valve on the evap unit.

Is there an accumulator or a receiver? I used a generic receiver/drier unit.

This is the compressor I am running:

It's a Denso 471-7031 New Compressor with Clutch

https://www.amazon.com/Denso-471-7031-N ... merReviews

Ok, I just went outside and got numbers for ya.

Current temp outside is 83*

At 1500 RPM, in Park, Evaporator fan on full blast:

Low: 50
High: 310



At idle (750 rpm) the numbers were low: 60, high: 220.

Vent temp was a pathetic 70*, with the van sitting still.

GottaBeCold88 wrote: ↑Fri Jul 15, 2022 12:18 pm Current temp outside is 83* At 1500 RPM, in Park, Evaporator fan on full blast:
Low: 50
High: 310

GottaBeCold88 wrote: ↑Fri Jul 15, 2022 12:18 pm At idle (750 rpm) the numbers were low: 60, high: 220. Vent temp was a pathetic 70*, with the van sitting still.

Somehow, your pressures are off. A low side of 50 PSI corresponds to an evaporator temperature of about 54°F, while a low side of 60 PSI corresponds to an evap temp of 63°F. So I'm not surprised that you're getting warm-ish 70°F air out of the vents. The high side at 1,500 RPM is much too high as well for an ambient of only 83°F, suggesting a condensing problem. We're not so interested in idle-speed pressures, though, only pressures taken at 1,500 to 1,800 RPM and at maximum heat load.

Correct me if I misunderstood. At first I think you mentioned a Sanden copy but later you mentioned a Denso compressor. Did you replace the former with the latter, or are they one and the same?

Just a guess, but it's possible that an overcharge and/or inadequate oil amount damaged the compressor internally in some way, which is now causing the unusually elevated pressures on the low side. Is the compressor making any strange noises?