A/C questions

[chris142]

thanks for the info guys.

ill suck it down and check out the orifice tube, maybe something got in it. then I might check out the compressor for oil.

I do have a blue orifice tube, should I give that one try? I know there different sizes but not sure of the specs on them.

No you want a smaller tube. Red or orange.

 

[no mufflers]

ok, a member here mentioned he had an orange one. ill check the parts store and see if they have one on hand.

does it seem like the orifice tube could be a problem?

 

[HS108]

That was me

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[needlenose]

...I've always assumed the compressor was what determined refrigerant volume...

I have a document from Sanden somewhere on my computer that describes how to determine the refer charge by calculating the total volume of space in the loop and plugging in some numbers for refer density and desired temp drop(or something like that). You can then determine the oil charge by calculating 8-10%(don't remember exact) of the refer charge.

I'm sure I left something out, but I think the compressor has much less to do with it than the size(volume) of the other components and the physics of 134a to get the proper pressures at known ambient temps with the proper lubrication.

I would add that the compressor has to be matched to the charge however. If it's too small it will run continuously and never shut off. Too large and it will short cycle. But it's the volume and pressure that determines the charges.

At least that's what I remember reading.

 

[franklin2]

I can't explain this, but several times after recharging a automotive system, right after it didn't seem to cool very well but a day or two later it cools better. On your next try if you still feel it's not cooling well enough, let it go and drive it the next day and see how it does.

 

[no mufflers]

so i got the orange orifice tube installed and recharged with 3 oz of oil and 2.80 lbs of Freon. the tube i took out was pretty dry so that's why i added some oil.

what i noticed was the large hose from the drier was starting to frost along with some of the fitting on the evap core. not sure if that is good or not. i did a fair amount of driving today with ambient temp at 85* and i was able to get a steady 58* from the vents. its better but not much. on long idle times it does stay cooler longer vs before it would go to 70* quick.

i thought i could smell some Freon or a/c oil odor while driving but it might have been me and it came and went.

any way, i still think the air should be a lot colder and if the evap can make frost then it should be really cold. i guess i will put a valve to bypass the heater core and see what happens. i have some pictures to show also.

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[F350camper]

going just off the last two pics @ ambient of 85° you look low to me. I'll let others weigh in cuz I dont do hvac for a living, but the frost / ice on the low side line and the pressures makes me think you are low.

 

[F350camper]

also, is there a chance your blend door isn't working correctly after your hvac controller swap?

 

[no mufflers]

also, is there a chance your blend door isn't working correctly after your hvac controller swap?

the blend door should be 100% but anything can happen. i do get a solid thump when i go to cold.

 

[79jasper]

What if you're hearing the max/recirculation door? Lol

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[needlenose]

...but the frost / ice on the low side line and the pressures makes me think you are low.

I tend to agree with this. If you can, pop the cover off your evap and look at it. If there's frost on it, your definitely low. It's freezing up and that's why your gaining temp.

Also, going by what I was taught, your high side should be 180 + ambient. Using that measurement, you're way low on the high side. This too indicates a low charge. Does the compressor cycle when idling parked?

 

[chris142]

The snow on the low side line is a good thing. Your ac is working well. Something in Your dash is allowing warm air to mix with the cold air.

 

[no mufflers]

The compressor will cycle a little.

The frost was when I just charged it. It had lessened after driving the truck for a while. I thought the pressure was low but just reporting for now.

 

[gnathv]

Put in a shot of freon at a time until that ice turns to condensate.

 

[needlenose]

BTW, I assume your machine has a scale? Are you charging from a single container or cans?