High Discharge Pressure
Thread Starter
|
Senior User
Joined: Sep 2005
Posts: 153
Likes: 0
From: Virginia Beach, VA
High Discharge Pressure
Every now and then, I run into a situation when recarging an A/C system on a car. Today I was charging up my buddies 93 E 150, and things went normal. Then I went to charge his 89 F 150 after a compressor change (hole on side), and the discharge pressure was high, real high, 225psi
, and short cycling.I evacuated the system, and took the orfice tube apart, and blew nitrogen through the entie system, thinking I had a blockage, blew out some old oil and dye in the evaporator. Blew clear. Evacuate system again, same pressures, bareley cool air.What gives?I do the larger systems all the time (supermarkets and such) but this has me stumped. Any help would be appreciated.
, and short cycling.I evacuated the system, and took the orfice tube apart, and blew nitrogen through the entie system, thinking I had a blockage, blew out some old oil and dye in the evaporator. Blew clear. Evacuate system again, same pressures, bareley cool air.What gives?I do the larger systems all the time (supermarkets and such) but this has me stumped. Any help would be appreciated.
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,078
From: St Louis
"hole in side"??? Was the high pressure popoff or a failure of the compressor case, or what. If it was a popoff, it could be due tot he same condition that is causing your excessive high side reading.
Did you flush the condensor and make certain it is flowing?
and center vent temp?
R12 or an R134a conversion?
How much refrigerant had been added when you got that high side pressure? What was the low side pressure, ambient temp,
Steve
Did you flush the condensor and make certain it is flowing?
and center vent temp?
R12 or an R134a conversion?
How much refrigerant had been added when you got that high side pressure? What was the low side pressure, ambient temp,
Steve
Thread Starter
|
Senior User
Joined: Sep 2005
Posts: 153
Likes: 0
From: Virginia Beach, VA
Good to see you again ProjectSHO89. It was failure of the case. It was pushing the ruuber seal out, and the case was splitting. I purged the condensor with nitrogen, had good volume out of it. The center vent temp was 50 at best, and the system was converted, but a 134 conversion on a R-12 system is remedial at best. I pulled the 134 out, and added an alternernative 12 replacement which works well in autos.And the low side is hovering around 25 psi. The truck didn't have a weight tag, so I went off pressure, I probably added 2- 2 1/2 pounds.
I'm willing to bet the condensor is somewhat plugged. I'll try cooling it with water while it's running and see if it helps. Any other advice?
I'm willing to bet the condensor is somewhat plugged. I'll try cooling it with water while it's running and see if it helps. Any other advice?
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
If there's no gunk in the orifice I;ll bet the fan clutch is bad. Mist water over the condenser. If the pressure drops like a stone, the fan clutch is history. That's probably what caused the first compressor failure.
Which alternate refrigerant are you using?
Which alternate refrigerant are you using?
Thread Starter
|
Senior User
Joined: Sep 2005
Posts: 153
Likes: 0
From: Virginia Beach, VA
I hit the condensor with the water, and the pressures dropped, but not like a rock.Maybe 30 psi or so.Studied it for a bit, hit it every now and then, the suction remained basically the same, but was sweating back like I like.The vent temp was hovering around 40 degrees.I think I'm going to agree with SOH89, and replace the condensor. I did the ol' sheet of paper in front of the condensor trick after I cleaned it, and it sucked it up fine. The discharge pressure steadily increased indicating that the condensor wasn't doing it's job.
I'm using the HOT SHOT alternative refrigerant, it goes for about $9 a pound wholesale.It's the first year using it, it is almost identical to 12. I used to use R-409A with good results, but figured I'd give this one a try. So far, so good.
I'm using the HOT SHOT alternative refrigerant, it goes for about $9 a pound wholesale.It's the first year using it, it is almost identical to 12. I used to use R-409A with good results, but figured I'd give this one a try. So far, so good.
