Installing Aftermarket AC in a Dodge Van

[tbirdtbird]

Posted by DetroitAC July 28, 2022

"Your suction line pressure drop is the problem I think. Is it kinked or squished flat anywhere? any chance you can change to #12 hose?"

[GottaBeCold88]

Yep i remember that comment, haha. I hope the additional port by the evap unit will help confirm or deny that speculation.

[GottaBeCold88]

So I just plumbed in this little guy. Got it vacuumed down, going to charge it up later this week and measure some pipe temps and pressures!

I understand I’ll probably be going to a #12 pipe, but before I go ripping everything #10 out I want to make sure that doing so is absolutely necessary.

Thanks everyone for following along and being patient with me!

[GottaBeCold88]

[GottaBeCold88]

Alrighty folks, finally got back at it today and charged the van back up.

First of all, as you know I added in a second service port right by the overhead evap unit inside the van. This was to see pressure closer to the place where I was reading cold pipe temps with my infrared thermometer, and also to see if the pressure inside the cabin was different from under the hood, closer to the compressor. Remember it is a long #10 hose that snakes through the a-pillar and has several fittings along the way: evap, firewall inside, firewall outside, underhood service port, compressor.

I also swapped out my eBay electric fan for a SPAL fan, just for haha's. I felt like the eBay one I had didn't really move much air. SPAL seems way better.

The other thing I did was change the TXV back to factory settings. Remember I turned it out 1 full turn before. So I turned it back in one full turn.

I kept adding oz after oz of r134a, but for some reason my low side PSI didn't seem to want to get too high. In the end, I went all the way up to 46.7oz with only 20 psi on the low side, and high side getting up to 350 (is that scary?). Vent temps never below 56F, on this 85F day.

My research leads me to believe that the evap is now starved for refrigerant. But I would love to hear opinions.

Also, the inside low-side service port consistently reads 5 psi higher than the under the hood service port. Does this mean I should definitely bump up to a #12 hose?

As usual, check out my chart of readings below:

[tbirdtbird]

"the inside low-side service port consistently reads 5 psi higher than the under the hood service port"

This indicates the amount of pressure lost in the long suction line

350 Hi is kinda high.
Is there any way you can include the old pressure table you made with this current page so we don't have to flip back and forth

According to your table, it appears you have a 60+F temp drop at your condenser. Not sure that can really happen.
I think it would be better to have a column for temp into condenser and an adjacent column for temp out of condenser. At least it would be easier to understand the data

I am gonna defer to Detroit on the rest

[DetroitAC]

5 psi drop is not bad at all, especially with your very highly superheated suction gas. No need for #12 hose, isn't going to improve this situation, and I'm gathering changing it would be a pain. Suction hose size isn't really your bottleneck after all. TXV superheat setting as originally thought could be the issue, but it could also be a restriction somewhere on the liquid line. In the van's current state, what is the temperature of the liquid being fed to the TXV? Should be hot, maybe a few degrees cooler than the condenser outlet. Also, does the TXV have it's own screen inside the small inlet fitting? could be plugged. Maybe check the next time you recover? Also, are there any markings on the TXV you can see? maybe it's not sized correctly, for a different refrigerant, ?

I wouldn't be worried about 350 psig in the condenser, also not worried about a large temperature drop across the condenser, it's a symptom of having way too much suction superheat. Lots of inlet superheat yields lots of outlet superheat. When the suction superheat problem is fixed the condenser inlet superheat will also be fixed

[tbirdtbird]

Superheat is quite high closer to 10 would be better...
Source of the TXV? It seems to be very difficult to get specs on auto AC parts, but a 1.5 or 2 ton rating would be ideal. Here is a link to the only chart I could ever find. Maybe Tim has charts or better sources.
https://www.uacparts.com/legacy/Search/ ... Dimen.html

It was better on the last chart
Here is that chart

ScreenShot-2022-07-27-at-4-00-37-PM.jpg (231.99 KiB) Viewed 4708 times

[GottaBeCold88]

Hey, thanks guys.

Here's a link to my chart, it'll work better than the image I think:

https://quick-jodhpur-b87.notion.site/C ... a2771f02d1

As far as my TXV, it does have some markings on it, looks like it is a 1.5 ton r-134a valve. I think I might replace it, actually. Who knows, maybe it is some junky off-brand peice that has some poor machining inside of it or something?

Glad I don't have to go to #12 hose. I was worried I wouldn't be able to fit the #12 hose through the A-pillar.

So it sounds like the TXV needs to be turned back out again? That, coupled perhaps with a great amount of r-134a?

going on vacation for the next week so I won't be able to work on it for a bit. But I did just order an ACDelco TXV off amazon. If someone knows a better TXV option, let me know.

[tbirdtbird]

How many tons was the valve you ordered?
EDIT:
Also do you know the rating of the current valve? I have never seen the tonnage rating marked on the outside of an MVAC TXV. It has to be researched via PN. I have also never seen a rating over 2 tons. With that much superheat, there is no way the system can perform much at all. Not enough 134 is getting through. Does your liquid line run near any heat-producing parts such as exhaust manifold etc?
We had a guy on here a short while ago who went on for many many pages, and once we convinced him to post a pic of his setup, it was time for a forehead slap. The accumulator sat right over the turbo and downpipe. The system had to remove that extra heat (which was way in excess of the heat it was supposed to remove [cabin heat, heat of compression, and heat generated by the compressor itself running]). He had jacked with the turbo and didn't want to own up. There was no way that system was ever gonna work properly. If your liquid line is close to exhaust, etc, then insulate it. A compressor and condenser can only do so much.

BTW an MVAC supplier here had an entire shipment of TXVs that were junk.
Sure you (Americans) want cheap? You want China? You get what you pay for.

As to your system, I am still just throwing out thoughts. AFAIC Detroit is the one with his hand on the tiller.

Are you able to answer his other questions about possible kinking, etc?