What is the correct high/low pressure for an R12 system?

[IS300E30]

System totally vacumed clean. New reman compressor, new evaporator valve, new drier and filled up with the correct BMW Spec of R12 and Mineral oil.

The problem is my low side pressure is 53

What could the issue be?

The compressor kicks on, the aux fan comes on.

I am going to take the front grill off and the kidney off and use a fin comb in case there are any bent fins on the condenser and I am going to spray down the condenser to maybe clean it out. I am hoping this will help in the cooling problem I am having.

[Jacksone30]

I think the pressures are indicate on the compressor no ?
And the range has a correlation to the ambient temp http://www.ackits.com/aacf/ptchart.cfm

Also it is marked under the hood somewhere I think
High side is within range?

[IS300E30]

High side supposely is within range. He stated it was between 225-250....Is that within range?

[F200]

55 and 225 sounds high on both sides. You may be over serviced, CM

[IS300E30]

Over serviced...Meaning too much freon was added?

[Jacksone30]

High side supposely is within range. He stated it was between 225-250....Is that within range?

Since a new compressor was put in I have to ask why? Did the old one seize?
Because if they seize and go bang the dump crap into the system.
From what I read , and I read a lot recently cause I am replacing my compressor soon. The system should be dis assembled and flushed.

That being said if there is crap in the system there could be a blockage somewhere causing the pressures to be off. I am not an AC expert (yet).

Bad news if there is crap in the system let's hope it does not make it's way back to the compressor and go BANG!

I recently read this http://www.e30tech.com/forum/showthread.php?t=82528
And I learned a lot found a lot more info on AC at e30 tech
C-ya

[Jacksone30]

I forgot to ask -what is the vent temp? And ambient temp of the air? That may tell you something too.

[T77911S]

yes, when both hide and lo are hi, it is either a very hi heat load on the system or you are over charged.
poor air flow over the condensor will raise the hi side. so make sure the fans are working and the coil is clean and as you are doniing, straighten the fins.
a hi low side is an indication of a hi heat load, too hi a fan speed (not your problem) or as stated, if both are hi, too much r12

the best way to charge the system is by weight. i just went through this last night on the phone with my brother. when charging a less than optimal system, which we all have since coils can be dirty, fins bent, compressors are old, ect, it is a comprimise when charging unless you weigh it in.

you have a site glass also. you can use that along with the pressures.

for r12 and 90 degrees outside, fan on hi, and recirculate, lo side should be 30-35 and high side should be 160-200. the hi side may have a broad range or be high due to air flow over the condensor. i am not concerned if the hi side is a bit higher as long as the lo side is right.
some cars a different, porsches may be as much as 300 on the high side. piss poor condensors/airflow

sorry to ramble, its early

[Jacksone30]

you have a site glass also. you can use that along with the pressures.
sorry to ramble, its early

Sorry to thread jack - what about the sight glass? We looking for what?

[T77911S]

the site glass should NOT have bubbles in it. a few are ok, but if it is really low, you will see it.

again, if at all possible, weigh it in. otherwise, you really only need gages for trouble shooting the system.
for 134, you can buy and "idiot" gage and hose at advance. it has a yellow, green and red section on the dial.

[IS300E30]

Thanks for everyones responses.

The reason I changed the compressor is that it was leaking horribly.

My low side as stated was 53lbs, my high side was between 225-250 my mechanic stated.

The mechanic also believes the issue is that my remanufactured compressor is a defect. I have no way of telling other then him telling me this after he put the gauges on it.

I am located in Western North Carolina (Asheville/Hendersonville area) so the temps are somewhere between 80s-to low 90s.

Also, another thing of concern. A member from the R3V BMW forum thinks I purchased counterfit R12. Now, I am concern of that as well

Not sure what to do next. I wish I knew someone around me that had access to R12 that I can trust and knows how to fill up the E30s like it is supposed to.

[F200]

I would not think your compressor is bad. You would not have such high side pressure if it was.

The a/c system is a closed loop system. The compressor circulates the freon through the system. The expansion valve makes a calibrated restriction. That makes every thing between the expansion valve and the compressor high pressure and everything between the expansion valve and the compressor low pressure.

If your expansion valve sticks open your pressures stay about the same because there is no restriction in the system. If you have a blockage or a stuck closed expansion valve you will have very high high pressure and very low low pressure. The high and low pressure switches save the system from damage if that occurs.

You have about the right pressure differential so that's why I thought you might just have to much freon. I have no idea what your pressures would do if you have something other than R12 in there.

Hope this helps,,,, CM

[IS300E30]

That does help, thank you.

Now, my question is, is there a way to take out some of the freon out of the system? Since a few people mentioned on here and R3V that they think I have too much freon in the system.

Is there a way to take out the extra amount that is making it not cool correctly?

I would not think your compressor is bad. You would not have such high side pressure if it was.

The a/c system is a closed loop system. The compressor circulates the freon through the system. The expansion valve makes a calibrated restriction. That makes every thing between the expansion valve and the compressor high pressure and everything between the expansion valve and the compressor low pressure.

If your expansion valve sticks open your pressures stay about the same because there is no restriction in the system. If you have a blockage or a stuck closed expansion valve you will have very high high pressure and very low low pressure. The high and low pressure switches save the system from damage if that occurs.

You have about the right pressure differential so that's why I thought you might just have to much freon. I have no idea what your pressures would do if you have something other than R12 in there.

Hope this helps,,,, CM