2nd Gen Non-Engine/Transmission Weakening AC

My AC keeps cooling less and less. I guess i should add freon as I don't like the idea of paying some AC shop well over $100 just to add/check out the system.

I have never done it on the new systems, is it any different from F-12?

How hot does the output have top get before it will take a can?

 

This is what I do . Get the r-134 recharge kit and an ac thermometer(small dial on the end of a long probe). With the engine running check the temperature at the center ducts by inserting the probe. Turn the fan to the highest speed and ac on. If the temperature is 45-50 degrees after running for 5 minutes or so you do not need refrigerant. If you need to add refigerant hook up the hose to can as per instructions with kit and the other end to the low pressure fitting(the one by the turbo). With the engine still running add the r-134 until the thermometer reads 45-50 degrees. This can take a few minutes!Shut off can tap and disconnect hose and put cap back on the low pressure tap, you're done!

 

Based on your reply, chances are you need to just add refrigerant. However, to make a totally accurate diagnosis. You need pressure gauges on the high and low sides of the system as well as thermometers in the discharge of the air ducts and on the liquid line entering the TXV.

If you're going to just follow georgej's instructions, I would add to make sure to keep the idle up slightly to make sure the compressor spinning good.

Good luck.

 

This should shed a lil light

The air temperature in the test room and in the vehicle must be a minimum of 21° C (70° F) for this test.



Connect a tachometer and a manifold gauge set.

Set the a/c heater mode control switch knob to the recirculation mode (Max-A/C) position, the temperature control knob to the full cool position, and the blower motor switch to the highest speed position.

Start the engine and hold the idle speed at 1,000 rpm with the compressor clutch engaged. If the compressor clutch does not engage, (Refer to 24 - HEATING & AIR CONDITIONING/CONTROLS/A/C COMPRESSOR CLUTCH COIL - DIAGNOSIS AND TESTING).

The engine should be at operating temperature. The doors and windows must be closed and the hood must be mostly closed.

Insert a thermometer in the driver side center A/C (panel) outlet. Operate the engine for five minutes.

The compressor clutch may cycle, depending upon the ambient temperature and humidity. If the clutch cycles, unplug the a/c low pressure switch wire harness connector from the switch located on the accumulator (A/C LOW PRESSURE SWITCH). Place a jumper wire between the two cavities of the a/c low pressure switch wire harness connector.

With the compressor clutch engaged, record the panel outlet discharge air temperature, the discharge pressure (high side), and the suction pressure (low side).

Compare the panel outlet discharge air temperature reading to the Performance Temperature and Pressure chart. If the temperature reading is high, clamp off both heater hoses (inlet and outlet), wait five minutes and record the temperature again. Compare the second reading to the Performance Temperature and Pressure chart. If the temperature reading is now OK, see Temperature Control Cable in the Removal and Installation section and in the Adjustments section of this group. If the temperature reading is still too high, (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - DIAGNOSIS AND TESTING), and (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE) in this group. Performance Temperature and Pressure

Ambient Temperature 21° C(70° F) 27° C(80° F) 32° C(90° F) 38° C(100° F) 43° C(110° F) 49° C(120° F)

Center Panel OutletDischarge Air Temperature 5 to 7° C(40 to 45° F) 13 to 16° C(55 to 60° F) 16 to 21° C(60 to 70° F) 21 to 24° C(70 to 75° F) 27 to 29° C(80 to 85° F) 29 to 32° C(85 to 90° F)

*Suction Pressure (Low Side) 241 to 276 kPa(35 to 40 psi) 276 to 345 kPa(40 to 50 psi) 345 to 414 kPa(50 to 60 psi) 414 to 483 kPa(60 to 70 psi) 483 to 552 kPa(70 to 80 psi) 552 to 586 kPa(85 to 90 psi)

*Discharge Pressure (High Side) 931 to 1000 kPa(135 to 145 psi) 1207 to 1482 kPa(175 to 215 psi) 1482 to 1862 kPa(215 to 270 psi) 1862 to 2275 kPa(270 to 330 psi) 2344 to 2551 kPa(340 to 370 psi) 2758 to 2965 kPa(400 to 430 psi)

*Note: If pressures are lower than shown, but center panel outlet discharge air temperatures are OK, then the A/C system is OK.



Sounds like about 100 bucks worth

 

There are a few differences between r 12 and 134. You will not find a sight glass on the r134 systems and they are not as forgiving in charge amounts like r-12.

 

For anyone with a Dodge truck and A/C problems: Pay special attention the the charging valves. It seems that they are prone to leaking.

 

Just a little insight on problems I was fighting with my truck for nearly 2 years... My heater core went out/leaking. When they replaced the core (seems leaking core is a huge problem w/these trucks). I don't know if there was junk in the lines or what, but the dealer kept having to recharge recharge and recharge it nearly once a year, sometimes a couple times a year. Well they actually dropped the working pressure and I have not had a problem since then. It was determined that I may have "garbage" in the line and when the system would get upto its normal / max pressure the over pressure outlet would dump the coolant. This took a total of nearly 4 years to finally find the solution. They did it last fall and this is the first spring that it still works!!!!! Best of luck. OH! When my problem originally started it was the core leaking the coolant out. Bed over and grab your ankles... cost me nearly 1k for the replacement/labor...



Corey

 

Don't forget to check and make sure the condenser drain on the fire wall isn't plugged up. Adding refrigerant is easy. It's worth the cost of a gauge to be able to do it yourself.

 

If you are leaking refrigerant over time (all systems leak, some are just more prone to than others... ), and you add for example, one 12oz can of R-134a to the system, you should probably add some PAG oil to the system as well. Approx 2oz is plenty. The oil leaks out with the refrigerant.



Many auto stores carry R-134a with 1 to 2oz of oil already in the can. Make sure its PAG oil, not ESTER.



Schucks carries 3 different viscosities of PAG oil in 2oz containers. Use the MEDIUM (ISO 100) viscosity. You add it just like the can of R-134a.



The AC compressors don't run very long w/o oil... just a little bit is needed, don't overdo it.



I can always tell when mine needs R-134a. The evap starts to get frozen (no airflow in cab) and the liquid line (smaller diameter going to firewall) gets a coating of frost on it.



When I add the R-134a to the system, I can watch the liquid line thaw immediately. This happens because the orifice for the system is behind the air cleaner box, not at the firewall (for noise issues) and the low pressure refrigerant after the orifice starts to freeze in the engine compartment. Low refrigerant levels = very low - low side pressures...



BTW - one 12oz can of R-134a is plenty. The AC system capacity is approx 22 oz if I remember correctly.





Regards,

Louis

 

Bob,

I have a 2001. 5 and every two years or so I have to add R134. I have not seen a leak and assume it is so slow, it might take a black-light test with tracer to find it. Today, I hooked up my el-cheapo low-side/charging gauge. Ambient temp was about 92 degrees, 50% humidity, idle was about 800 (not the recommended 1,000) and I had to add 3 cans (12oz each) of R134 to get the low side to 52psi with the compressor on (max A/C). My center vent was about 58 degrees after 5 minutes or so. Is this about all our systems will do in this heat/humidity? I had the hood up too so I wasn't pulling all the air I could through the condenser. (compressor was cycling every few seconds with 25psi on the low side when the clutch cycled off before I added the refrigerant). Is 36oz seriously overcharged? My low side was constant at 52psi on Max A/C after adding 3 cans.



Thanks,

Mick

 

36 ounces seems high. Check the capacity sticker on the cowl just above the radiator. My 1996 calls for 24 ounces total, but cools best with 20 ounces. Have you vacuumed the system to about 28 inches to boil off moisture? Did it hold vacuum for about 1/2 hour? At those conditions, I can get mine down to about 55 degrees in the driveway, 46 driving.

 

Mine started out like that. I put a can in it and it was good that summer. Next year it wouldnt hold the charge. It was the evaporator. #@$%!

I just replaced my evap and H core. Running good now.

 

Mine seems to go at least 2 years, never any sooner. I must have a VERY slow leak at the seals.



Thanks,

Mick

 

I just had the dealer top off my 97 today. this was the first recharge ever for it. 60 bucks and I am CCCCool again. (Well at least the truck is. )