A/C Pressure too high.

[Rowdy Dalton]

I had the a/c system replaced 7 years ago, and it has had a very slight leak, requiring a couple of pounds of Freon, each summer. I use a gauge, and install Freon myself. Last week I noticed the a/c wasn't working. I thought it was time to add more. I checked, and it showed the pressure well into the red zone. I thought the gauge was bad, and used another. That too showed it pegged in the red. So, I released the pressure, on the low side. A lot of oil shot out, and I did this for about 30 seconds, until the Pressure came down to the correct levels, both with the compressor engaged and not engaged. No extra Freon was needed.
The A/C compressor now operated normally, everything cooled as it should. It's been a week and it still works fine.
What is going on here??

 

[Ozymandias]

The cheap can gauges don't work on these Gen RAMs at all, they always show low and you keep adding and adding.
You need a set that shows you low and high side at the same time, and best is to charge it by weight.
Which can he done by taking it down to 1psi resting pressure and then charge the amount you need.

But now you have a bigger problem, as you said you drained an amount of oil too and that stuff is crucial to be in there in the right amount too.

I'd consider to have the system serviced by a professional and tell him about the lost oil.
As long as you didn't use a can with a sealant in it, if one of these cans was used you are dommed, no professional will ever touch that unit again as it would contaminate his equipment.

 

[Rowdy Dalton]

The cheap can gauges don't work on these Gen RAMs at all, they always show low and you keep adding and adding.
You need a set that shows you low and high side at the same time, and best is to charge it by weight.
Which can he done by taking it down to 1psi resting pressure and then charge the amount you need.

But now you have a bigger problem, as you said you drained an amount of oil too and that stuff is crucial to be in there in the right amount too.

I'd consider to have the system serviced by a professional and tell him about the lost oil.
As long as you didn't use a can with a sealant in it, if one of these cans was used you are dommed, no professional will ever touch that unit again as it would contaminate his equipment.

Yep, then I guess I am doomed. On the whole, it was probably only a tablespoon of oil or a little more, spewed out.
I was just wondering why it would build so much pressure. Is there some kind of relief valve, in the a/c system, that should keep it in check?

.

 

[Topzide]

@Rowdy Dalton, Go and get at least a HF set of gauges, a pocket thermometer and print out of pressure tables referenced to outside temps. That way you can see the cycle pressures and compare to charging tables. As @Ozymandias stated, if you've used freon with sealer, no service guy will work on again. And if you don't tell in advance, you'll get a big surprise on the bill! You have to pay for his equipment to be flushed and serviced! Get the freon with the A/C dye built into it and see if you can find and fix the leak. Had A/C system apart in '01 1500. Pulling the dash is the bad part if needed!!!!!!!!!!

 

[jghflys]

I use the procedure and the bands below in the chart to add to existing charge. I get satisfactory results without evacuating the system.

A/C PERFORMANCE TEST

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION. FAILURE TO FOLLOW THE WARNINGS AND CAUTIONS COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH .

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

1. Perform the A/C System Performance Test found within the HVAC System Test. If no diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM), go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2.
2. Connect a tachometer and a manifold gauge set.
3. Set the A/C-heater control to the Recirculation mode (max-A/C) position, the temperature control to the full cool position, and the blower motor control to the highest speed position.
4. Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged. If the A/C compressor does not engage, see the A/C Diagnosis chart.
5. The engine should be at operating temperature, the doors should be closed and the windows opened.
6. Insert a thermometer in the driver side center panel outlet and operate the A/C system until it stabilizes.

NOTE: The A/C compressor clutch may cycle, depending upon the ambient temperature and humidity. If the clutch cycles, use the readings obtained before the clutch disengaged.

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Performance Temperature And Pressure

 

[Ozymandias]

Yes it's pretty much easy to fix the AC.
All you need is that Set of gauges and a decent vacuum pump. Got mine from Amazon then, get a dual stage for the proper vacuum.

 

[Rowdy Dalton]

Unfortunately, I used a can of freon, with sealer in it, several years ago. I have looked at buying all the gauges, as well as the vacuum pump, but am afraid the sealer inside the system might damage them.

 

[Topzide]

@Rowdy Dalton, Just get some A/C flush to put through your gauge set or pull all the components of your system and flush everything, seal it back up with a new dryer and expansion valve, pull vacuum and charge after confirming system is sealed. Gauges, vacuum pump, dryer,expansion valve, new o-rings, A/C flush and freon will get you back to having some A/C. It's not that bad of a job, just time consuming! Flushing out everything is the worst part beyond having to pull dash! Here to help with questions if needed. Good luck with repairs!

 

[Lordsman]

Probably non-condensibles in system; air, moisture. That's the reason for high head pressure. Find, fix leak and then as others have said pull a good vacuum on system. Then weigh in the correct refrigerant charge. Condenser coil is first in line to get hit by rocks or debris getting through front grille so check there for a leak. Good luck on repair!

 

[bcbender]

It is pretty easy to inject dye into the system, then where ever the leak is it'll be easy to find. That is how my friend found out his evaporator on his Merc was leaking, yellow dye was coming out with the condensate. Then as others have said, discharge, flush and clean, then replace the exp valve and dryer.. Recharge and be done.