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We have a 1990 BMW 325i that the A/C quit working on. The pressure was low so I obtained more freon to charge the system up. I added the charge and the compresser started engaging the clutch. Now, the low side is over 55 lbs, overcharged, and I have added less than 10oz of gas. Would that mean the compressor is dead? Oh yeah, the capacity of the system is 2.01 lbs so I know it's not full yet.
<div class='quotetop'>QUOTE(RedHeartbeat @ Jun 18 2006, 08:09 PM) [snapback]55713[/snapback]</div>Quote:
We have a 1990 BMW 325i that the A/C quit working on. The pressure was low so I obtained more freon to charge the system up. I added the charge and the compresser started engaging the clutch. Now, the low side is over 55 lbs, overcharged, and I have added less than 10oz of gas. Would that mean the compressor is dead? Oh yeah, the capacity of the system is 2.01 lbs so I know it's not full yet.
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maybe a cloged orfice tube or something?
Hi Red, :duh: Yes I would agree. My book says pressure 2 high on low side- pressure 2 low at high pressure side= internal leak in compressor. It is pumping up but leaking backward. :twocents:
I agree with the compressor too. What's the high side reading? If the compressor is dead it will be significantly lower also.
<div class='quotetop'>QUOTE(NITROUS @ Jun 18 2006, 10:46 PM) [snapback]55721[/snapback]</div>Quote:
I agree with the compressor too. What's the high side reading? If the compressor is dead it will be significantly lower also.
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Hmmm.... just went out and double checked the pressures on the high and low sides after getting about 18oz of freon installed. At idle I've got 60psi on the low side and 240psi on the high side. At about 1500 RPM it has 45psi on the low side and 325 psi on the high side. This was all in the evening hour with 63% humidity and 81 degree outside temperature.
HVAC can be alittle tricky to diag somtimes. Just going by your post and gauge readings.... I still need more info... Was the system vaccumed or at least vented prior to charging?
There are many reasons for high suction and discharge pressures. The most common would be air in the system, adding refrigerant to the system would not correct this. The system would need to be vaccumed down or at least vented, Then recharged to get some good readings for diag. It is very common to leak refrigerant and suck air into the system.
If you can recover the refrigerant and put the system into a vaccum. If this is not possable, Vent the system to purge the air and recharge the system and report back with readings.
A stuck open expansion valve will cause the same symptons as well as non functioning coolings fans...
Basic things to check for High Discharge...
Air in system
Clogged condenser
Discharge valve closed
Overcharged system
Insufficient condenser air;
High Suction Pressure...
Overcharged system
Expansion valve stuck open
Compressor reed valves
Leaking head gasket on compressor.
HTH
Sounds like it could be many things. I didn't pull a vacuum since the system still had pressure on it when I pressed the schreader valve in. I bled the pressure out of the system until it got very low, but not totally evacuated. The system has a low pressure switch that kept the compressor from engaging the clutch at low static pressure. I know I got about 18oz in the system last night. We are going to drive the car in the heat and see what it does, a 450 mile trip today. We don't know the history of the car but know that it has been in a front end collision before since the core support is deformed and the hood has been replaced. Maybe the condensor is mangled, don't know for sure. As a last resort I may just replace the compressor and all the hard parts and recharge with 134a to upgrade it. Ebay lists the compressors for $145, a lot better than $340 at Autozone and $570 at Oriellyauto.
If the compressor vavles was bleeding by the head pressure would be lowers than 325. Sounds like a bad expansion valve. I don't think you have a bad compressor. Most of the the time pressures go hand and hand, high discharge the suction should be high to unless there is restriction. If you stay with a chevy you can just change that easy orfice tube for about 5 dollars.
Yeah, damn Kraut cars. :laugh:
The car did well and we stayed confortable all day. Thank God for that. The drive was tense enough without being overheated due to lack of A/C. Our only issue is at idle we lose most of the cold air flow. Oh well, it's a highway car for cruising. I don't drive it in the city, she does. Would the expansion valve cause the issue with low RPM not making cold air and cause the high low side pressure?
A simple test for the expansion vavle... If you can get asscess the the capillary bulb blast it with refrigrant or somthing supper cold... lowside will come down if not go into a vacumm if working proplerly... I suspect this as well and would be one of my first tests. I also dont think the compressor is even a factor at this point... But if you can get one for $140! get it..
:wave: Hello Redheartbeat, Did you figure out what was up with your AC? Enquiring minds would like to know. Thanks :hshake:
It's working good enough. Just recharged it with 134a after evacuating the system and adding the new PAG oil.
COOL I like easy fixes