AC SYSTEM RECHARGE EXPERIENCE

[etozion]

PROBLEM: my AC system shut off few weeks ago and message came up like “low refrigerant level, AC compressor turned off”.

PROCEDURE:

1) Engine off. Ignition key turn to ON;

2) Check on-board codes. Have AC1347 as current code;

3) Clear codes;

4) Engine off. AC off.

5) Ignition key turn to OFF. Disconnect Low Pressure Switch Connector (13) and jump it with a paper clip;

6) Wear protective gaggles and gloves;

7) Remove the black cap from Low-side Service Port (11);

8) Prepare a refrigerant kit. In my case, I purchased 19 oz can (16 oz of refrigerant R-134a and 3 oz of oil and something special) with dispenser valve and pressure gage, I removed protective ring, screw tight the dispenser head with gage;

9) Hook up the refrigerant hose to the Service Port;

10) Set AC at 60-65F (max cold). Turn engine on. Turn AC on;

11) Check the pressure readings on the gage. If it’s on the “green zone” start adding refrigerant;

12) The compressor goes on and of constantly (it surprised me) sucking refrigerant;

13) This process is slow (it surprised me too). Keep filling with refrigerant and watching pressure on the gage. The pressure goes (in my case) up to ~60 psi and down to ~15 psi with each compressor off and on cycle. With time, interval of compressor switching becomes longer and low point pressure rises into the “blue zone” ~30 psi. I stopped at 30 to 40 psi;

14) After charging system with refrigerant turn engine off;

15) Disconnect the refrigerant kit and put back protective plastic cap;

16) Remove jumper from the Low Pressure Switch Connector (13) and plug it back;

17) Start your car and enjoy cooool air (in my case in 110F outside).

I hope this is useful.

[KHE]

Rather than jumping sensors with paper clips, Disconnect the negative battery cable for 30 seconds, hook up a can of R-134a, burp the air from the hose, and then reconnect the negative battery cable. Start the car and set the climate control to 60 and the system will pull in the refrigerant before the code sets.

I recommend adding pure R-134a vs. R-134a with oil, sealer, etc. Usually, the system doesn't need oil unless there is a major leak. In that case, it's best to inject PAG-150 oil as that is the correct oil for the A/C system. Many times kits contain ester oil which is not the proper oil for GM A/C systems.

[Bruce Nunnally]

Nice post; good clear info.

Also good to understand that if there is a leak it has to be repaired before more refrigerant is added.

[jfreezn]

<<14) After charging system with refrigerant turn engine off;

15) Disconnect the refrigerant kit and put back protective plastic cap;>>

Not to nitpick, but a potential safety item exists if you turn off the engine with the can still connected. Depending on the discharge pressure, the system pressure will quickly equalize into the can at something like 120 to 150 PSI. The can is good for over 100 PSI, but I just wouldn't want to take a chance on some cheap can. Besides, disconnecting the can at 30-40 psi, while the AC is running, will keep more refrigerant in the system.

If you can safely stick your arm into the area where the hose connects (not always possible), I would definitely release the hose while the engine is running.

Regards,

Jim in Phoenix

[etozion]

If you disconnect the negative battery terminal your personal settings (radio presets, etc.) will be probably lost (?). (At list it’s true for my Buick).

Good point about safety. The reason I did not disconnect the can - I purchased refrigerant with a detachable dispenser valve, so the pressure point is in the valve, not in can.

[mike5514]

Paper clip great idea! I had the same problem a while back and did something with the dic (cant remember) but the papar clip is much easier. only caveat is dont leave the clip on too long. but a Aplus idea thanks mike

[etcxtc]

Air conditioning systems are not an area I have a lot of expertise in (in fact, little to none), so with that said when using these "off the shelf" recharging systems can you over charge and cause damage to the system? Is any one particular "off the shelf unit" better and safer than any other?

[KHE]

Air conditioning systems are not an area I have a lot of expertise in (in fact, little to none), so with that said when using these "off the shelf" recharging systems can you over charge and cause damage to the system? Is any one particular "off the shelf unit" better and safer than any other?

Don't use any refrigerant with sealers or o-ring conditioners mixed in. Just use plain R-134a.

Yes - it is possible to overcharge the system - especially using a gage that only monitors the low side pressure.

[etcxtc]

Don't use any refrigerant with sealers or o-ring conditioners mixed in. Just use plain R-134a.

Yes - it is possible to overcharge the system - especially using a gage that only monitors the low side pressure.

Since it is possible to overcharge the system, how do you know when enough-is-enough?

[etcxtc]

Ok, (Insert Explicative Here! ) what did I do wrong on the insertion of a quote?

[Scotty]

I imagine that Kevin will tell us how its done with guages, but at my AC shop, they actually physically measure how much 134A is put into the system. There is glass level on the side, they mark off two pounds and add 134A till they reach it.. Surprisingly easy.

[WarrenJ]

Ok, (Insert Explicative Here! ) what did I do wrong on the insertion of a quote?

The closing quote should be .

When I did mine recently, I cleared the code at the dash. No need to disconnect the battery.

If you overcharge, the compressor will blow off the excess. Still, it's best to use a gauge.

Regards,

Warren

[etcxtc]

The AC in my '98 Deville hasn't shut down the compressor for lack of freon, but I've been noticing that it just isn't as cool as it once was. I thought it might be prudent to add some 134a and see if that helps, but I don't want to do any damage to the system.

When you say

If you overcharge, the compressor will blow off the excess. Still, it's best to use a gauge.

Does is blow off via a pressure relief valve or with my luck lately does it blow the lines and/or compressor off the car?

[WarrenJ]

When you say

If you overcharge, the compressor will blow off the excess. Still, it's best to use a gauge.

Does is blow off via a pressure relief valve or with my luck lately does it blow the lines and/or compressor off the car?

Funny!

The relief valve is on the rear of the compressor. Don't count on it to give you an exact charge. It WILL protect you from disaster, however.

Regards,

Warren

[WarrenJ]

The AC in my '98 Deville hasn't shut down the compressor for lack of freon, but I've been noticing that it just isn't as cool as it once was. I thought it might be prudent to add some 134a and see if that helps, but I don't want to do any damage to the system.

In my most recent experience, and the first one for Baby, the A/C cooled like a Siberian wind right up to the instant the DIC gave me the bad news that I'd better open the windows.

I went down the block and purchased a recharge kit (gauge, hose, 134a). When I finished, the can still "felt" full. I don't imagine the system sucked in much gas at all.

In short, I'd be disinclined to think low refrigerant would account for less cooling than you are used to.

OTOH, you could try 'topping off." I'd be happy for you if you proved me wrong.

Regards,

Warren

[Ranger]

For what it is worth, my car seemed to be somewhat inefficient in the cooling department. It had never been serviced. Some of you may remember the ebay fiasco that actually turned out in my favor after a few months when purchasing a set of guages last fall, but I digress. I checked it this spring and although I never got the low refrigerant message, I was infact low. I added 2 cans to get the pressures up to specs and it now cools quite well.

[WarrenJ]

For what it is worth, my car seemed to be somewhat inefficient in the cooling department. It had never been serviced. Some of you may remember the ebay fiasco that actually turned out in my favor after a few months when purchasing a set of guages last fall, but I digress. I checked it this spring and although I never got the low refrigerant message, I was infact low. I added 2 cans to get the pressures up to specs and it now cools quite well.

WOW! The system capacity is only 2.0lbs (0.906kg). And you added two cans? It's hard to understand how your compressor might still run under those circumstances.

OKAY, I looked it up! What a concept! My manual says "If the system's refrigerant state of charge should fall below 1/4 of its capacity, a "VERY LOW A/C REFRIGERANT - COMPRESSOR OFF" message will be displayed and the ACP will store a DTC (A047 and/or A048) in memory (Remember: I'm talkin' a 1995 manual)."

Ranger, in your case that thing sucked up nearly two cans while the compressor continued to operate. In my case, a nearly imperceptable amount was required to get the compressor running again.

If I sound confused, it's b/c I am. And, yes, I did the math (for 12 0z. cans). Theoretically, you were right on the edge (not counting residual contents of the cans). Me, I wasn't even close.

Regards,

Warren

EDIT: etcxtc, top that sucker off!

[KHE]

Don't use any refrigerant with sealers or o-ring conditioners mixed in. Just use plain R-134a.

Yes - it is possible to overcharge the system - especially using a gage that only monitors the low side pressure.

Since it is possible to overcharge the system, how do you know when enough-is-enough?

The exact method is to recover the remaining refrigerant and compare it's weight to the specification on the accumulator.

You can only approximate the charge with high and low pressure readings as ambient temperature and relative humidity play into the equation. An A/C system isn't a tire That said, you can use the performance chart in the shop manual and add refrigerant to achieve the high and low pressures for a given ambient temperature and relative humidity while monitoring the vent outlet temperature. Place a large fan in front of the condenser and raise the engine RPM to 1500 while charging.

I do not recommend adding refrigerant until the relief valve opens...you will lose a lot of refrigerant oil, not to mention wasting the refrigerant. You can also be severly injured if liquid refrigerant touches your skin.

[Ranger]

For what it is worth, my car seemed to be somewhat inefficient in the cooling department. It had never been serviced. Some of you may remember the ebay fiasco that actually turned out in my favor after a few months when purchasing a set of guages last fall, but I digress. I checked it this spring and although I never got the low refrigerant message, I was infact low. I added 2 cans to get the pressures up to specs and it now cools quite well.

WOW! The system capacity is only 2.0lbs (0.906kg). And you added two cans? It's hard to understand how your compressor might still run under those circumstances.

OKAY, I looked it up! What a concept! My manual says "If the system's refrigerant state of charge should fall below 1/4 of its capacity, a "VERY LOW A/C REFRIGERANT - COMPRESSOR OFF" message will be displayed and the ACP will store a DTC (A047 and/or A048) in memory (Remember: I'm talkin' a 1995 manual)."

Ranger, in your case that thing sucked up nearly two cans while the compressor continued to operate. In my case, a nearly imperceptable amount was required to get the compressor running again.

If I sound confused, it's b/c I am. And, yes, I did the math (for 12 0z. cans). Theoretically, you were right on the edge (not counting residual contents of the cans). Me, I wasn't even close.

Regards,

Warren

EDIT: etcxtc, top that sucker off!

Yeah, I thought that was a lot myself. Maybe I should check it again. I do have a B1313 code. I wonder if maybe I am a little overfilled? I added til I got the pressures to where they were supposed to be.

[WarrenJ]

I do not recommend adding refrigerant until the relief valve opens...you will lose a lot of refrigerant oil, not to mention wasting the refrigerant. You can also be severly injured if liquid refrigerant touches your skin.

A point well taken.

[KHE]

For what it is worth, my car seemed to be somewhat inefficient in the cooling department. It had never been serviced. Some of you may remember the ebay fiasco that actually turned out in my favor after a few months when purchasing a set of guages last fall, but I digress. I checked it this spring and although I never got the low refrigerant message, I was infact low. I added 2 cans to get the pressures up to specs and it now cools quite well.

WOW! The system capacity is only 2.0lbs (0.906kg). And you added two cans? It's hard to understand how your compressor might still run under those circumstances.

OKAY, I looked it up! What a concept! My manual says "If the system's refrigerant state of charge should fall below 1/4 of its capacity, a "VERY LOW A/C REFRIGERANT - COMPRESSOR OFF" message will be displayed and the ACP will store a DTC (A047 and/or A048) in memory (Remember: I'm talkin' a 1995 manual)."

Ranger, in your case that thing sucked up nearly two cans while the compressor continued to operate. In my case, a nearly imperceptable amount was required to get the compressor running again.

If I sound confused, it's b/c I am. And, yes, I did the math (for 12 0z. cans). Theoretically, you were right on the edge (not counting residual contents of the cans). Me, I wasn't even close.

Regards,

Warren

EDIT: etcxtc, top that sucker off!

Yeah, I thought that was a lot myself. Maybe I should check it again. I do have a B1313 code. I wonder if maybe I am a little overfilled? I added til I got the pressures to where they were supposed to be.

B1313 is the high side temp sensor circuit short code. Overfilling shouldn't set that code. If it cools satisfactorily, I wouldn't mess with the charge. Once the code becomes "current", then you will need to recover the refrigerant to replace the sensor.

[Ranger]

Yeah, I agree. I suspect it is a bad sensor and probably will leave it alone til it causes a problem.