R134a cooling - acceptable or is there a problem?

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bohica2xo
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Re: R134a cooling - acceptable or is there a problem?

Post by bohica2xo »

Whenever you transplant an electric cooling fan, you need to take the whole heat exchanger stack.

The 2005 GMC the 6.0 came from had a stack & fan assembly that worked. Taking some of it may work as well, but using the whole thing as designed would be the best option.

The Lincoln fan? A 2 passenger car with a 4.6L engine? Not the best choice. If you ever looked at the Lincoln underhood, there was a huge engine setback. The fan discharge ran unobstructed for about 18 inches. The bodywork generated a fair amount of underbody suction too. The whole system worked well together.

Your truck has more interior volume in the front seat than the entire Lincoln.

If you do recover it, consider the oil overcharge possibility as well - that question is still open.
foamypirate
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Re: R134a cooling - acceptable or is there a problem?

Post by foamypirate »

Thanks again for your input, as always.

I haven't yet had a chance to take the truck to get evacuated to swap the o-tube, but today, we had a nice storm blow through, and the temp dropped to about 82F and 80% humidity.

Not sure if this is relevant or helpful to determine charge, but I did a bit of an experiment. I had the truck running in the driveway, engine fans full bore, doors open, and the interior fan turned to the lowest setting. The accumulator was literally so cold I couldn't keep my hand on it for a long duration. Even the rubber hose back to the compressor (about 1/2 of it, anyway) was sweating (though the humidity was quite high).

Does this indicate an overcharge or undercharge? I'm afraid if temps drop any lower, if I end up running the fan on slow speed, I'll slug the compressor with liquid refrigerant. Or would the LPCO kick in and shut the compressor down before that happens? Am I just seriously overthinking this?
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Re: R134a cooling - acceptable or is there a problem?

Post by bohica2xo »

The compressor should cycle when you get enough liquid refrigerant in the accumulator.

Slugging would be hard to do, here is what is inside that accumulator:
https://www.youtube.com/watch?v=eOzA2FeJ_Fk

With the fan on low & 80% RH, you should see a very wet to icy accumulator. It should cycle - if you cool the interior down & put the cabin fan on the lowest speed.
foamypirate
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Re: R134a cooling - acceptable or is there a problem?

Post by foamypirate »

Cool video, I always enjoy learning how things work.

Made a lot of progress today. We dropped the charge down to 26 oz, and things are WAAAY better. 90F, and even after extended idling, the high side was around 280-290 (still a bit higher than I'd like, but certainly better than 350-375). The HPCO no longer trips, even with about 1,500-1,800 RPM. The low side was 44-45. With the fan on max, and going down the road, I saw the vent temp dipping into the 46-48 degree range. Turning the fan speed down one notch resulted in 42 degree temps, and the clutch started to cycle. Once I finished my test loop, I popped the hood, and the whole accumulator was sweating, along with about 1 foot of rubber hose on the suction line off the accumulator. I think the charge is pretty much right on now. I might play with dropping the low pressure cut out just 1 or 2 psi to get that last little bit of cooling, being careful not to ice the evaporator, of course, but overall, MUCH happier with the system! I'm blown away by how small the charge is. I guess that PF condenser compared to the giant factory dual tube serpentine, and my shorter than factory hoses made quite a difference in system volume.

Thanks again for all the help and input!
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Cusser
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Re: R134a cooling - acceptable or is there a problem?

Post by Cusser »

foamypirate wrote:Made a lot of progress today. We dropped the charge down to 26 oz, and things are WAAAY better. 90F, and even after extended idling, the high side was around 280-290 (still a bit higher than I'd like, but certainly better than 350-375). The HPCO no longer trips, even with about 1,500-1,800 RPM. The low side was 44-45. With the fan on max, and going down the road, I saw the vent temp dipping into the 46-48 degree range. Turning the fan speed down one notch resulted in 42 degree temps, and the clutch started to cycle.
Great. Now leave it alone.

bohica2xo wrote:here is what is inside that accumulator..
Yeah, once I cut down a drier from my R-12 system, was surprised how small the desiccant bag was.
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