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Chris
Chris, Shop Foreman
Category: Dodge
Satisfied Customers: 13012
Experience:  Dodge/Cummins and Chrysler Certified Master Tech
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I found this article helpful when installing my new

Customer Question

I found this article helpful when installing my new compressor however I now have to recharge it. I have a separate vacuum pump and no way to get r134a other then auto part stores. I am epa certified however I do not know my system. Can you help walk me through the procedure
Submitted: 1 year ago.
Category: Dodge
Expert:  Chris replied 1 year ago.

Hello and welcome to just answer. Do you have a set of 134A gauges also?

Chris

Customer: replied 1 year ago.
I do, however I believe I need to get a set of adapters
Expert:  Chris replied 1 year ago.

Ok, well when you get the adaptors and then follow the procedure below:

REFRIGERANT SYSTEM CHARGE

WARNING: REVIEW SAFETY PRECAUTIONS AND WARNINGS IN THIS GROUP BEFORE CHARGING THE REFRIGERANT SYSTEM.

AVOID BREATHING A/C REFRIGERANT AND LUBRICANT VAPOR OR MIST. EXPOSURE MAY IRRITATE EYES, NOSE AND THROAT. USE ONLY APPROVED SERVICE EQUIPMENT MEETING SAE REQUIREMENTS TO DISCHARGE R-134a SYSTEM. IF ACCIDENTAL SYSTEM DISCHARGE OCCURS, VENTILATE WORK AREA BEFORE RESUMING SERVICE.

R-134a SERVICE EQUIPMENT OR VEHICLE A/C SYSTEM SHOULD NOT BE PRESSURE TESTED OR LEAK TESTED WITH COMPRESSED AIR. MIXTURE OF AIR AND R-134a CAN BE COMBUSTIBLE AT ELEVATED PRESSURES. THESE MIXTURES ARE POTENTIALLY DANGEROUS AND MAY RESULT IN FIRE OR EXPLOSION CAUSING PROPERTY DAMAGE, POSSIBLE PERSONAL INJURY OR DEATH.

CAUTION: Do not overcharge refrigerant system, as excessive compressor head pressure can cause noise and system failure.

CAUTION: A small amount of refrigerant oil is removed from the A/C system each time the refrigerant system is recovered and evacuated. Before charging the A/C system, you MUST replenish any oil lost during the recovery process. Refer the equipment manufacturer instructions for more information.

The procedure below should be used to fill the refrigerant charge in the A/C system. This A/C system does not have or use a sight glass to check or charge the system.

After the system has been tested for leaks and evacuated, a refrigerant (R-134a) charge can be injected into the system.

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.

If the A/C compressor does not engage, test the compressor clutch control circuit and correct any failure (Refer to 8 - ELECTRICAL/WIRING DIAGRAM INFORMATION - DIAGNOSIS AND TESTING).

  1. If using a separate vacuum pump close all valves before disconnecting pump. Connect manifold gauge set to the A/C service ports.

    NOTE: Always refer to the underhood HVAC Specification label for the refrigerant fill level of the vehicle being serviced.

  2. Measure refrigerant (refer to the underhood HVAC Specification label). Refer to the instructions provided with the equipment being used.
  3. Verify engine is shut off. Open the suction and discharge valves. Open the charge valve to allow the refrigerant to flow into the system. When the transfer of refrigerant has stopped, close the suction and discharge valve.
  4. If all of the charge did not transfer from the dispensing device, put vehicle controls into the following mode:
    • Automatic transmission in park or manual transmission in neutral
    • Engine at idle
    • A/C mode control set to outside air
    • A/C mode control set to panel mode
    • A/C temperature control set to full cool
    • Blower motor control set on highest speed
    • Vehicle windows closed
  5. Open the suction valve to allow the remaining refrigerant to transfer to the system.

    WARNING: TAKE CARE NOT TO OPEN THE DISCHARGE (HIGH-PRESSURE) VALVE AT THIS TIME. FAILURE TO FOLLOW THIS WARNING COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH.

  6. Close all valves and test the A/C system performance.
  7. Disconnect the charging station or manifold gauge set. Install the service port caps.

REFRIGERANT CHARGE CAPACITY

The R-134a refrigerant system charge capacity for this vehicle can be found on the underhood HVAC specification label.

Customer: replied 1 year ago.
What pressure should the system be evacuated to?
Expert:  Chris replied 1 year ago.

About 28 to 30 inches of mercury (vacuum).

Chris

Expert:  Chris replied 1 year ago.

Hello, just checking back to see if you received my last reply, and if so do you still need help with your problem? Please remember, the website will not automatically credit me from your deposit or subscription without your Rating! Please, use the Rating System Box and Rate our Q&A session today or. If you need to ask more questions, please feel free to ask!

Thank you!

Chris

Customer: replied 1 year ago.
Well I got the compressor installed system evacuated and recharged. It worked great for 50 or so miles and stopped working. Any ideas?
Expert:  Chris replied 1 year ago.

Hmmmm, could be several things. Possible leak, new compressor is defective, electrical problem, or a blockage. Connect the gauges again and tell Me what the pressures are.

Chris

Customer: replied 1 year ago.
Both high and low are 100. Compressor is not kicking on
Expert:  Chris replied 1 year ago.

If you jump 12 volts to 5he compressor, will it engage and blow cold?

Chris

Customer: replied 1 year ago.
it did
Expert:  Chris replied 1 year ago.

Ok, then this is an electrical issue between the AC clutch relay and compressor or a sensor like the pressure sensor or evaporator coil sensor. Tell me this: if you remove the ac clutch relay and jump terminals #30 to #87, will the clutch come on?

Chris

Customer: replied 1 year ago.
that worked
Expert:  Chris replied 1 year ago.

Ok, i need to look over the wiring diagram and see what the next step is. Be back asap.

Chris

Expert:  Chris replied 1 year ago.

Ok, there are 2 sensors that can cause the compressor to not come on: 1 the pressure transducer on the high side line next to the compressor, and 2 the evaporator temp sensor in the evaporator coil in the HVAC housing under the right side of the dash. The problem is you need a capable scan tool to properly diagnose them. Can you get a scan tool that will read those sensors? if so that would be great. If not, then you can try replacing the sensors and see what happens.

Chris

Customer: replied 1 year ago.
I do not have a scan tool. Do I need to evacuate the system to replace both these sensors?
Expert:  Chris replied 1 year ago.

No you don't have to discharge or evacuate the system to replace either sensor.

Chris

Customer: replied 1 year ago.
Cool. I will replace the sensors and get back to you. Also I have a noise when my ac or heat is on. It sounds like a fan clutch but it's only there when ac or heat is on. Is the fan clutch going bad or would that be something else I need to worry about...like a brand new ac compressor for instance
Expert:  Chris replied 1 year ago.

Sounds good. I don't think it is the fan clutch but could be the compressor or maybe a serpentine belt tensioner.

Chris

Customer: replied 1 year ago.
How do I fix it?
Expert:  Chris replied 1 year ago.

If the noise is coming from the compressor, then replacethe compressor. If it is coming from the belt tensioner then replace it. Use a mechanics stethoscope to pinpoint the noise.

Chris

Customer: replied 1 year ago.
I replaced the sensor on the high side next to the compressor. This did not fix the problem. Fuse, relay and connector on the sensor I just replaced are all good. Is the only other possible failure in the low pressure switch or could it be something else?
Customer: replied 1 year ago.
Update. The terminal 89 for the ac clutch relay is not constant. When the truck is off it is a ground and when it is running it is a positive or vice versa I don't remember. If you need the correct information let me know but can you explain why this is and if it is a possible problem related issue
Expert:  Chris replied 1 year ago.

Do you mean terminal 86?

Chris

Customer: replied 1 year ago.
86
Expert:  Chris replied 1 year ago.

Ok, 86 should have power with the key on. That is the power fed to the relay's coil. Then terminal 85 should supply a ground to the relay when you turn on the relay. Tell me, when you jump the relay and turn on the compressor, does the air get cold?

Chris

Customer: replied 1 year ago.
it does
Expert:  Chris replied 1 year ago.

Ok, at this point I am thinking you have a bad evaporator temp sensor, or a failing PCM (engine computer ) I am going to recommend that you spend the money to have a diagnostic scan tool connected to the truck and see if it is the PCM or the sensor. I will bee off line and on vacation for about 10 days but will check back with you when I get home.

Chris

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