a/c pressure question: hot at idle, cool at speed

[WOTStang]

’96 Escort 1.9 CCOT system.

2 years ago I replaced the evaporator, the condenser, accumulator, orifice tube & compressor, and the correct amount of PAG 46 to each component. these were all all o’reilly parts. i replaced everything but the lines, which i back flushed, evacuated it for an hour and charged it properly and everything seemed to work ‘alright’. This was in summer 2012. Everything was replaced because it has the dreaded FS-10 compressor which is very famously known for ‘black death’. When i took everything apart to have it replaced, you could clearly see all the evidence.

Fast forward about 3 months ago. I noticed the new (now 2 years old) compressor leaking oil at the bottom of the case, and the refrigerant charge was low. I evacuated & recharged the system and now my a/c will work ok when driving, but as soon as i come to a stop it will be warm. (normally a classic condition of a failed condenser/fan.) Im getting about 70º vent temps at idle. I verified a/c clutch operation, cooling fan is working fine. I hook up my gauges and i see about 40-50psi low side.. and 250psi high side (Hot Texas 100º day. High blower speed, windows open @ idle.)

Now this is where it gets interesting.. if i’m in the car and i raise the RPMs to 1500, i start to get cooler air (60º).. however when i look at my gauges, my low side drops as it should, but my high side will sky rocket to 275,300,325,350,400.. in about 10-15 seconds. Obviously high side is anything from compressor to the orifice tube… so that leads me to believe i have a big restriction at either the condenser or maybe the orifice tube? (obviously it *is* a designed restriction.. but maybe its plugged up with junk?). Also, even when im driving on recirculate and high blower speed.. my vent temps are in the low 50’s, which makes the car take quite awhile to cool down. I mostly always have to use the highest blower speed to keep the car cool too.

i have a bad feeling i bought a reman. compressor that broke down due to a low oil condition (never saw a case leak on a compressor before) and flooded my condenser/system with debris.. out of the 10 pistons this compressor has, it probably is working on 7 or 8 of them… the rest of them have broken down and plugged up the condenser and is causing an abnormally elevated high side pressure. That is my guess…

Obviously the compressor needs to be replaced (due to the oil leak at the case.) But it almost seems like the whole system would need to be done again due to possible compressor break-down and contamination

Any input on what i could check or what the possible problem might be? Im really curious what is making the high side pressure spike so drastically.

Topic

[Tom]

Unfortunately, I think you are already looking in the right direction. You def need to address the leaking compressor, but I would carefully examine the remainder of the system for contamination from the compressor failing.

[WOTStang]

[quote=”Tomh” post=106921]Unfortunately, I think you are already looking in the right direction. You def need to address the leaking compressor, but I would carefully examine the remainder of the system for contamination from the compressor failing.[/quote]

that is definitely the plan. 🙂

Anyone else have any input on the spike of high side pressure i mentioned? Just want to confirm there could be a restriction on the high side of the system.. although i’ve always heard that you will see frost where a restriction is forming, which i have none of.

[Its me]

I am not so sure you have a restriction, but would not discount it….

A leak from a compressor can be expected at some time (certainly not expected after two years)….

Anytime there is a leak in the system, weird things can happen…

Since you are going to replace the compressor, then it is only prudent to inspect the orifice tube…

You have few options (As I think you see as well)… The only other option is to remove the refrigerant, evacuate and see if the system holds.. (which it should not)… Which will lead you to find a leak…. Which you have confirmed already at the compressor…. so this is a waste of time… and since you have the compressor off, you already know to re-check the orifice tube…

No matter what you do, I think you will find the problem (to what degree, will be discovered)… After you replace the compressor and as long as the system holds vacuum and the orifice tube is clean, you just need to recharge with the proper weight of refrigerant all should be well..

JMHO

-Karl

[Author]

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