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I'm installing a used a/c compressor that came with my engine pullout. The engine came from a car low miles and still had all the lines attached. It even leaked a little more freon after I removed the manifold and lines from the compressor. I'm on the fence about changing the compressor oil. I will be replacing the lines, drier, etc. but the condenser and evaporator are original and were functioning before the swap. I'll clean both of those as well...
Any advice on what to do with the compressor? Just run it? Add oil or change the oil?
I'd recommend changing it. Not least because, you don't know how much is in it. Drain & refill with the right amount.
Agreed. If the system has been exposed to air it will absorb moisture. It's a very simple process and PAG oil can be purchased at any parts store and or amazon. Measure what you pour out, and pour the same amount of new back in.
IIRC that is a V7 compressor. You will likely have to change the control valve to get the evaporator cooling correctly. V7 in a retrofit application, I typically get the 2nd lowest pressure valve if it is not already installed.
IIRC that is a V7 compressor. You will likely have to change the control valve to get the evaporator cooling correctly. V7 in a retrofit application, I typically get the 2nd lowest pressure valve if it is not already installed.
Admittedly, I'm not an a/c expert. When you say control valve, are you talking about the high side pressure switch? If so, I had planned to use the 4th gen switch. Is that the switch or are you talking about something like the cycle switch or something different altogether?
Admittedly, I'm not an a/c expert. When you say control valve, are you talking about the high side pressure switch? If so, I had planned to use the 4th gen switch. Is that the switch or are you talking about something like the cycle switch or something different altogether?
Thanks for the input...
Bill
It is a valve that installs in the compressor housing that controls when the compressor destrokes. The V7 has a variable stroke and does not cycle the clutch to control evaporator core pressure. The only time a V7 cycles is if the minimum stroke is still too much capacity.
Oh boy! Thanks for pointing this out. Where can I get the correct switch? I've tried Google and I only see places in Australia. I will continue my search but any help is appreciated.
This is the last set I picked up. I used the lowest pressure, IIRC Yellow. There is a 39 psi unit available but it is for applications that had a very long suction hose. I start low and work up if the evaporator core starts freezing up on a ~30 minute drive. Use a R134a spec cycling switch on the accumulator that is calibrated to cut the compressor off at 21 psi. Ideally the compressor should run as close to possible to a point of freezing the evaporator core and not below. When you turn down the fan speed on a cooler day, if the compressor cannot maintain the pressure through reducing its displacement enough then the compressor cycles.
I just looked, Camaro is speced for a 41 psi valve, it would probably be fine as is with minimal cooling loss compared to the 40 psi valve I used. 1 psi changes the boiling point about 1°F, not a huge change.
I should also say when I said retrofit earlier on that style compressor, it was actually a V5 on an earlier GM and a R12 to R134a retrofit but the V7 is the same in that regard. The V5 and V7 are nearly identical, the V7 just has 2 more pistons and more displacement allowing it to move more refrigerant. Thus higher BTU capacity. The V7 and even V5 for that matter are overlooked and very underated units. An old GM A6 was always noted for being a monster in terms of BTU capacity. The A6 could move 42,000 BTU. The V7s 14 kw capacity is 47,770 BTU. At full stroke the V7 can certainly eat some power though, at 4,000 rpm that 9 kw power consumption is over 12 hp. At that RPM with a single evaporator system, the V7 will be running at a much lower stroke than full capacity though. The beauty of the V7 is it has displacement on demand and at idle and lower rpm the compressor can move enough refrigerant to keep the ac blowing practically as cold as moving down the road, provided your condenser has adequate airflow across it to keep the pressures down.
Yesterday I drove about 200 miles round trip, which was the first time I’ve taken the car out for a longer drive. About an hour in, I noticed the air starting to feel warmer, so I figured the refrigerant might have leaked out. I shut the A/C off, rolled down the windows, and kept going. After parking for about an hour, I tried the A/C again and it blew really cold, so I think it must have just frozen up? I did swap the control valve to the yellow one as recommended. Overall, I’m pretty happy with how it performed.
