Thread: a/c high side at 525 psi... something is way wrong

In the process of restoring my B13 A/C, I took my A/C system apart and started to repair it. The o-rings were all replaced to the new green ones. The condenser was not leaking any Freon and seemed overall in good shape aside from a few bent fins on the lower part of it. Aside from a junk load of dead bugs and leaves, the evaporator looked good. All the parts where cleaned and washed with a water hose, I also installed a new expansion valve and drier.
The a/c oil was all dumped out of the compressor and replaced with ester oil. This is where I am thinking that I messed up because I added in 6.8 oz of oil, I was not thinking cause I bought this crappy kit to retro-fit to r-134a and the cans had 1 oz of oil and leak sealer. So now it has 9.8 oz of oil in it. The a/c did not work so I evacuated the system once more and drained the oil for the compressor and about 3 oz came out of it.
When I hooked up my gauges to test the system I had the low side from 30-45 and the high side was up about 450psi. So I once again vacuumed out the system again repeatedly per the FSM and then left the last vacuum on for about 2 hours.
After this the system started to cool really good I was able to get it to 44 degrees and the high side was about 250psi and not really getting any higher so I thought I was good to go

2 days later...
The high side pressure relief valve blew and per the FSM that is good to 525psi, so now I am lost on what I should try next.
Anybody got any ideas of what could be happening?
My next steps are to remove the whole a/c system and flush out all the lines, evap, and condenser. From what I have been reading is that either too much oil or bad condenser coil.

Not really sure at this point.

Sounds like you did all the right things.I would pull the compressor,dump all the oil out,and refill with the correct oil and correct amount.That's a good start.What kind of low side pressure were you reading once you charged it? And what was ambient temp? I rarely see any more than 200-225 on the high side, even during our recent 100+ temps.Almost sounds like the expansion valve is clogging with something.I've seen a condenser clogged up recently,too.A/c would work great while you were moving,but the pressure would shoot through the roof when you were stopped.It was partially clogged,and promptly replaced.A/c is beauty now.It is, after all,a 20 year old car.

Woah 525psi.. Looks like u have a restriction somewhere.. Either your expansion valve is plugged or installed incorrectly with the thermostat.. What I would do is get an oem expansion valve.. Pull every line out and flush it and the condenser.. I'm pretty sure your
Problem is gonna be with the
Expansion valve..

Buy an oem valve and drier..

If you did the retrofit it will be nothing but issues..

my low side pressure after the final recharge was in moving around from 30 -60 but after about 20 min it settled at around 45 psi the temp outside was prob 95-100 and high side was around 250 and it was cooling perfect, then the day it happened (yesterday) the temp was 85-90 and i was on my way to homedepot to get me some insulating to put up in the roof. on the discharge hose there is a valve of some sort and its open now when before it was not.

i am sure i installed the bulb wrong (i used black electrical tape to attach to the line hahah was this my failure point?) does anyone have any tips on how to install the bulb of the expansion valve?

i'll add some pics to see if anyone might know where to get a replacement cause i called everywhere to look for this hose and napa has it but in texas and i live in kansas they said 3-5 days on freight. boooo

well so far i have removed everything but the evap and thats next but its pretty hot out and i wanted to check on this post.

does anyone know what the capacity of r-12 for this 92 sentra? i got a fsm for a 94 and it says 1.3-1.5 r-134a but i cant seem to find how much r-12.




the valve that blew

Remember if fans don't work correctly your pressures will rise sky high.. But that switch should of cut your compressor off when those pressures rise up..

28oz of freon is your capacity.. Yea that "bulb" needs to be against that evaporator..

28 oz thank you, i filled up 24 oz of r-134a so now i know i was not overcharged. the fans did come on and seemed to pull good amount of air but i have no way of testing acutal air flow so i gonna have to assume they are running fine. i have a water temp in my dash and that was reading 180f when the hose blew. im going to have to redo that bulb, the factory had some black foam around it attached to a/c line. i'm going to go look for that foam at home depot tomorrow and i'm am flushing all the lines, evap and condenser right now.

i really hope to find the root cause of this because it's hot in kansas and the humidity is super high everyday.

Yea check that thermostat "bulb"... It was 108 today
And 116 degrees yesterday and humid.. My car was blowing ice cold n got a headache lol.. You should of sticked with r-12 I could of sold u some since I have 2 30lb tanks and 3 cans laying around..n licensed to buy r-12 and resale it..

yes!!! i totally am regretting it now man but no turning back now, lets see whats up with this damn a/c.

i wonder if i can buy a brass fitting to cap off this valve?! hmmmmm sounds dangerous.

im sure greg v can get u another pressure relief cap.. or buy another hose.. their on ebay for like 55 shipped...