ofelas wrote:Hi, 91.5 truck with all 93 AC pieces -
Alrighty. I did the following -
New gaskets & o-rings everywhere. Nice!
5oz oil in the compressor, 2oz in condenser, 1oz in evaporator & 1oz in drier. I've not studied the FSM or sticker under the hood but I expect you're well in the ballpark regarding the quantity of oil. Spreading around the oil isn't necessary as I expect you know it'd get around the refrigerant circuit with normal operation.
- Did you remove all the original oil?
Nitrogen in the system at 300psi and it held for almost 2 hours - no drop in pressure at all. Good.
Ran 26psi vacuum on the system and it held for 2 hours. I expect you mean 26"mg (26 inches mercury vacuum). While that's much better than nothing, a digital micrometer would have told the tale of any possible leaks but would also include evidence of moisture in the system. The two-hour runtime may very well have removed possible moisture (I think I'm preaching to the choir here). LOL!
Sucked in 40oz of R12 with the compressor cycling at 1300rpm + Max AC + blower fan on high. Again, I'm assuming that's the correct quantity. The proper way to instill the new refrigerant in the evacuated/dehydrate circuit would have been to release all the liquid refrigerant of the high-side of the system . . . with the system OFF. Having instilled all it would take, then start the system and allow the balance of the refrigerant to be drawn into the suction side of the system as a VAPOR.
Here's hoping the compressor wasn't damaged by the oil being washed out / diluted, never mind the valves being hurt via possible slugging of the compressor.
Compressor OFF: 50psi low side and 220psi high side Assuming the system was OFF, for say, ten minutes, I'm concerned the evaporator pressure didn't equalize with the high-side. Do our TXV's have the external equalizing tube (built in of course)? If it does, that would explain your readings.
Compressor ON: 25psi low side and climbs in a few minutes to 450psi high side. The words you have typed here say the suction pressure started at 25psig, and rose to 450psig? Or did you run the two different readings together?
Faceplate vent temperatures - 46-50 F With what return-air temperature?
Raising the rpm to 1200-1300 turns the compressor OFF and high side drops almost instantly to 200-250psi. OK. A number of things can alter said reading.
Why am I getting such high side readings, and is it normal for the compressor to be ON constantly until it de-clutches at 1200rpm? Remember, the compressor is nothing more than a VAPOR pump. It's only going to move so many CFM of vapor per minute at a given RPM, incoming vapor density, etc. With a return-air temperature of 85*f, one may very well be boiling off enough liquid refrigerant in the evaporator such that, at a low pump RPM, the pump may run continuously. At a higher pump RPM, the same load on the evaporator may be low enough to have the pump cycle. Nothing out of the ordinary there.
Possibly fan clutch not enga
That 450psig reading is WAY too high ref"
http://www.refrigerants.com/pics/ptchart.pdf- When was the last time you cleaned the condenser coil (high strength detergent followed by a strong pencil stream of water flushing)?
- Is the engine coolant fan clutch whacked? With the engine well heated and the fan moving hot air, shutting down the engine, can you easily spin the fan and have it continue spinning (indicating the clutch is NOT engaged)?
- Is 40 ounces of liquid R12 the correct factory spec charge?
I apologize if my questions are sorta rough and straight to the point, I spend all day supervising the HVAC shop for North Carolina's largest county school system. It's been a long day . . . . all week.