Building an A/C system from near scratch

[KBScobravert]

Glad to see Kim's worked out for you!

The guy does good work but you have to give him deadlines. I REALY should have told him to have them finished by Friday at 2p. That would have allowed me to be two days ahead of where I am now. Days I am running out of before Thursday's trip to Oklahoma and back.

Any thoughts on renting/buying a vacuum and gauges set and charging this thing myself?

[redfiveohconv]

I'm in, this is good stuff.

[KBScobravert]

I'm in, this is good stuff.

Thanks. It is all for not though if the AC is not working come time for the trip Thursday.

[shumpertdavid]

I know I don't want anything with Stop Leak in it. Instead I used PAG100 with leak UV dye just in case.

dye is a good thing for sure. you will lose a little oil in the vacuum process, my a\c machine drains the oil it recovers at the end of the vacuum process and allows me to add oil through the lines before I fill it. As far as the charging yourself with a set of gauges the best thing I can tell you is to add the factory charge to it plus an extra .2 ounce to account for what the gauges and the charging hoses will hold. Like I said before, just trying to add by gauge readings is not an accurate way to ensure a proper fill.

[KBScobravert]

Stock calls for 2.13-2.2 pounds of R12. With the longer lines and the larger condenser I am going to put in 2 and expect to put about 2.5 in before the pressures get to where I read they need to be at.
ambient 90*f - 45-55psi (low side) 250-270psi (high side)

[shumpertdavid]

figured it would have been a r-134-a car stock, but 94 was the breaking year there were still a few that carried over on r 12. Rule of thumb used to be 80% of original charge amount when converting over. The best way to get a correct fill would be to use a surface temperature probe (not an IR thermometer) to measure the inlet and outlet of the evaporator core. You are looking for temperatures to be within 3-5 degrees of each other. This ensures the evaporator has a complete fill of freon running through it. However most people don't own the right temp probe to accurately read it. That being said I'd say your pressure readings are pretty close to what you'd like to see. Possibly a little lower on the low side, I'd look for 35-45psi.

Extra line lengths, bigger condenser, etc will require extra charge amounts, but would be minimal amounts I'd think.

[KBScobravert]

figured it would have been a r-134-a car stock, but 94 was the breaking year there were still a few that carried over on r 12. Rule of thumb used to be 80% of original charge amount when converting over. The best way to get a correct fill would be to use a surface temperature probe (not an IR thermometer) to measure the inlet and outlet of the evaporator core. You are looking for temperatures to be within 3-5 degrees of each other. This ensures the evaporator has a complete fill of freon running through it. However most people don't own the right temp probe to accurately read it. That being said I'd say your pressure readings are pretty close to what you'd like to see. Possibly a little lower on the low side, I'd look for 35-45psi.

Extra line lengths, bigger condenser, etc will require extra charge amounts, but would be minimal amounts I'd think.

Awesome. Thanks for the insight. I wished I could find a temp probe in the next 12hrs.

[KBScobravert]

I am almost done with the hour vacuum.

Bigshoe (Chris) loaned me the pump a gauge set.

...and it was/is a 134 car.

[greenbullitt]

I am almost done with the hour vacuum.

Bigshoe (Chris) loaned me the pump a gauge set.

...and it was/is a 134 car.

sweet! I was gonna say you could bring it by the shop one night, but glad Chris got you hooked up

[KBScobravert]

Took three cans but I know that each can still had some in it when I swapped them over. Compressor comes on an stays on. Idle does not drop enough to require IAC involvement. We were worried about that in the tune. Air reading at the vents are right between 50-55. No visible leaks with the green UV dye. Pressure steady with engine idle and compressor on. Video to follow.

[KBScobravert]

sorry the video sucks but you get the point. My frankenstien A/C works......so far

[shumpertdavid]

Is the low pressure cycling switch still on the accumulator, generally it will cycle the compressor off @ 25 psi. If it doesn't cycle off and on the system will freeze up. I would guess based on the pressures that you are still down some on refrigerant, I'd expect 250-275 with the heat right now and mid 30's to low 40 on the low side. Again, that's where the temperature differential at the evap inlet and outlet would help.

[KBScobravert]

Is the low pressure cycling switch still on the accumulator, generally it will cycle the compressor off @ 25 psi. If it doesn't cycle off and on the system will freeze up. I would guess based on the pressures that you are still down some on refrigerant, I'd expect 250-275 with the heat right now and mid 30's to low 40 on the low side. Again, that's where the temperature differential at the evap inlet and outlet would help.

Low PSI switch is in the factory spot, still on the accumulator, even a new switch.

There is another switch on the suction side of the accumulator to compressor between the low side charge port and condenser.

The compressor was pretty much staying on the entire time. So you think I should add more? I need to find an adapter hose for the screw top port on the cans to the yellow hose. Much easier than the can piercing clamp.

What about using this dude right here to top it off?

http://www.autozone.com/autozone/accessories/Quest-17-oz-of-R134a-and-2-oz-of-Sub-Zero-A-C-booster-with-shelf-saving-dispenser/_/N-261q?itemIdentifier=532242&_requestid=29826

[shumpertdavid]

Probably be ok, just make sure it doesn't have stop leak. The second switch should be in a high side line. It will be for high pressure cutout and should deal with cooling fan control. I would say based on pressures it could still be a little low.

[KBScobravert]

Probably be ok, just make sure it doesn't have stop leak. The second switch should be in a high side line. It will be for high pressure cutout and should deal with cooling fan control. I would say based on pressures it could still be a little low.

Thanks for your input. I doubt I would have gotten this far without your input on charging and design and same goes for dville_gt. Even though I know I wasted some of the R134a, I am glad I tackled it myself instead of taking it somewhere. Next time I will agitate the can to build the pressure higher to transfer.