AC charge attempt failed- compressor seized
11-07-2009, 11:20 PM
#1
Drifting
Thread Starter
AC charge attempt failed- compressor seized
AC experts, I'm looking for ideas on what went wrong....
I tried charging the system today after rebuilding the compressor, installing new AC hoses, new drier, and flushing the evap and condenser (while removed from car). I used ester oil with R-12. Total system capacity is listed as 9.3 oz oil and I put 4 oz in the compressor (Nippondenso 6E171), 2 in the high side line and the rest in the (new) drier.
Prior to installing the new drier the system was evacuated to 29.9+ for a half hour which it held for an hour. I then put in the new drier and pulled it down again to 29.9+ for a half hour. I charged (into the vacuum) one 12 oz can of R12 on the high side (not running) and my gauges equalized at about 55 psi. Ambient in the garage was around 65 F so I couldn't get much more in there statically.
I then started the car, turned on the AC to max and the AC clutch did engage. I started charging a 2nd can into the low side and noticed the pressures were not changing much. The low side increased a few psi and the hi side none at all. I tried bringing up the revs a bit but it still didn't seem to be taking more charge. Maybe 2 minutes elapsed before I shut the low side valve and tried to figure out what was wrong. Maybe a minute later the engine stalls. I turn off the AC, re-start the car and when I turned on the AC again it stalls the engine.... a bowl full of not good...
After things cooled down (compressor was HOT), I put a socket on the compressor and found it will only rotate back and forth about 3/4 of a revolution. After that in either direction it ain't moving!
So time for a 'post mortem' analysis of what I did wrong... It could have been a bad compressor to start with. It came from a parts car with no known history, however, it looked clean inside and the residual oil in there was clear. I didn't see any obvious signs of wear, cylinders looked good, swash plate good, etc. Installed new O-rings, front seal and clutch bearing. Put in 4 oz of ester oil in low side and I tested it by capping the hi side and putting a gauge on the low side and turning it around 10 rpm with electric drill. It produced around 20 in Hg vacuum.
I did flush the evaporator with the expansion valve in place. A bad move? I sprayed the flush solvent into the inlet, shook it around a bit, let it sit for several minutes and then applied compressed air (approx 90 psi) to force it through to evap outlet. Since it did come out I assumed this proved the exp valve was not plugged.
I'm hoping to learn what likely caused the compressor to seize so quickly. Was my method of charging flawed somewhere? Should I have just put all of the oil in the compressor? This was the first time I've tried to charge up a system from the ground up so to speak. I thought I did my homework though..
I tried charging the system today after rebuilding the compressor, installing new AC hoses, new drier, and flushing the evap and condenser (while removed from car). I used ester oil with R-12. Total system capacity is listed as 9.3 oz oil and I put 4 oz in the compressor (Nippondenso 6E171), 2 in the high side line and the rest in the (new) drier.
Prior to installing the new drier the system was evacuated to 29.9+ for a half hour which it held for an hour. I then put in the new drier and pulled it down again to 29.9+ for a half hour. I charged (into the vacuum) one 12 oz can of R12 on the high side (not running) and my gauges equalized at about 55 psi. Ambient in the garage was around 65 F so I couldn't get much more in there statically.
I then started the car, turned on the AC to max and the AC clutch did engage. I started charging a 2nd can into the low side and noticed the pressures were not changing much. The low side increased a few psi and the hi side none at all. I tried bringing up the revs a bit but it still didn't seem to be taking more charge. Maybe 2 minutes elapsed before I shut the low side valve and tried to figure out what was wrong. Maybe a minute later the engine stalls. I turn off the AC, re-start the car and when I turned on the AC again it stalls the engine.... a bowl full of not good...
After things cooled down (compressor was HOT), I put a socket on the compressor and found it will only rotate back and forth about 3/4 of a revolution. After that in either direction it ain't moving!
So time for a 'post mortem' analysis of what I did wrong... It could have been a bad compressor to start with. It came from a parts car with no known history, however, it looked clean inside and the residual oil in there was clear. I didn't see any obvious signs of wear, cylinders looked good, swash plate good, etc. Installed new O-rings, front seal and clutch bearing. Put in 4 oz of ester oil in low side and I tested it by capping the hi side and putting a gauge on the low side and turning it around 10 rpm with electric drill. It produced around 20 in Hg vacuum.
I did flush the evaporator with the expansion valve in place. A bad move? I sprayed the flush solvent into the inlet, shook it around a bit, let it sit for several minutes and then applied compressed air (approx 90 psi) to force it through to evap outlet. Since it did come out I assumed this proved the exp valve was not plugged.
I'm hoping to learn what likely caused the compressor to seize so quickly. Was my method of charging flawed somewhere? Should I have just put all of the oil in the compressor? This was the first time I've tried to charge up a system from the ground up so to speak. I thought I did my homework though..
11-08-2009, 12:45 AM
#2
Rennlist Member
I would have thought you did it by the book, but you're correct, you shouldn't have flushed thru the EV. I'm not sure you hurt it, but everything I've read is not to do it.
But I think what killed the compressor isn't related to that. I did exactly as you did (on a 134 system), as far as 4 oz in a brand new compressor, the rest as you described, and it seized right after charging was complete. All I can figure is that the 4 oz just isn't enough when the rest of the system isn't saturated with oil. The next time I fed in a can of freon/oil charge after establishing about 50 psi (static), when I jumpered the compressor clutch; no problems in 2 yrs.
I can imagine your pain what with losing a can or more of R-12!
But I think what killed the compressor isn't related to that. I did exactly as you did (on a 134 system), as far as 4 oz in a brand new compressor, the rest as you described, and it seized right after charging was complete. All I can figure is that the 4 oz just isn't enough when the rest of the system isn't saturated with oil. The next time I fed in a can of freon/oil charge after establishing about 50 psi (static), when I jumpered the compressor clutch; no problems in 2 yrs.
I can imagine your pain what with losing a can or more of R-12!
11-08-2009, 09:43 AM
#3
Drifting
Thread Starter
Well the R12 is still in there. Supposedly AC shops will pay you to recover it. We'll see... I found it hard to get a definitive answer on oil distribution. I'll probably try putting all 10 oz in the compressor on the next try...
11-12-2009, 09:35 AM
#4
Drifting
Thread Starter
I found out what killed the compressor.. One of the reed valve retaining nuts came loose and got into a cylinder. To its credit, the aluminum piston mashed the steel nut so it looks like a woodruff key... Luckily I shut things down before this resulted in aluminum debris getting scattered throughout the system.
So does anyone have a good used early compressor to part with (6E171 Nippondenso)? I do have one of the popular replacement Sanden's but I hate the idea of cutting my new hoses to fit up to this.
So does anyone have a good used early compressor to part with (6E171 Nippondenso)? I do have one of the popular replacement Sanden's but I hate the idea of cutting my new hoses to fit up to this.
