Ok, so first time poster long time listener. I've recently built a little variable speed (up to 5000 btu) DC hvac system and it is not operating at all like I expect.
1.) I have a masterflux hermetic compressor that runs on r134 and 12 volts.
2.) because of lack of funds and completely custom nature of this project I've cobbled together the condenser and evaporators using a busted up 5000 btu window unit I disassembled.
3.) because it is what the previous window unit used, I am running 1/4" line from the high side into the condenser. The condenser (not parallel flow as far as I can tell) then has some sort of small diameter coiled metering device back out into 1/4" line after the expansion. This then runs through 1/4" evaporator line back into the suction side that is expanded out to 1/2" to accomodate the pre brazed fittings to compressor. This expansion to 1/2 line happens about 8 -10 inches away from the accumulator near the compressor.
Now heres the problem, it isnt cooling anything. The only portion that is even relatively cool is the portion of the suction line right before going back into the compressor. I assume because there is quite a bit of room for the gas to expand. Is my whole problem that my evaporator lines arent large enough?
Also i was told that it does not matter where the low side service port is mounted as long as its on the low side, however the low side service port is also mounted right before the accumulator in the 1/2" tubing. I could never get the pressure above 12 psi and I had it filled with 20 oz of r134. With the system off, the pressure would rise well above the low side guage reading.
I assume the pressure reading is because of the expansion of the tubing dropping the pressure in that section.
Please help me, I'm a year invested into this build and this is a major setback. I suspect I need to run larger evaporator lines so the gas can properly expand but I'm just guessing and would appreciate any advice you guys can give me before I set out to reconfigure the whole thing. Id rather not waste any more time or money than I already have.
Thanks for any help you can give me.