A/C - Poor Performance, Suction Side Shows Low or Vacuum
Classification:HA97-002a
Reference:
NTB97-007a
Date:
January 15, 1998
Subject:
1993-97 ALTIMA POOR AIR CONDITIONING (A/C) PERFORMANCE-LOW PRESSURE GOES INTO VACUUM
APPLIED VEHICLE:
1993-97 Altima (U13)
APPLIED VIN:
Vehicle built before 1N4BU31D*VC138483
APPLIED DATE:
All vehicles built through June 11, 1996
SERVICE INFORMATION
If a 1993-97 Altima vehicle has poor air conditioning system performance, there may be two causes.
1. An evaporator core with an internal bypass condition. This condition causes refrigerant to flow from the expansion valve directly to the low side hose without going through the heat-exchange portion of the evaporator core itself. This incident is identified by lower than normal high side pressures and low side pressures going very low or going into vacuum. There will also be frost on the pipe from the evaporator to the compressor. In this case you must replace the evaporator assembly.
2. Loose desiccant from the liquid tank which plugs the expansion valve. This incident is identified by lower than normal high side pressures and low side pressures going very low or going into vacuum.
In this case you must replace the following components at the same time:
^ Liquid tank
^ High cooler pipe "A"
^ High cooler pipe "B"
^ Evaporator inlet tube
^ Expansion valve.
The high/low side pressures are similar. The best method to identify the evaporator incident from the loose desiccant incident is that the pipe from the evaporator outlet to the compressor inlet is heavily frosted in the evaporator incident.
SERVICE PROCEDURE
1. Connect an ACR4 machine (or set of suitable gauges) to the vehicle service ports.
2. Conduct A/C system performance and operational testing. Refer to page HA-32, DIAGNOSES - Overall System, Performance Chart in the 1993 service manual. Refer to the HA section under TROUBLE DIAGNOSIS, Performance Chart in the 1994-97 service manuals. Make sure you use the correct chart for the manual or automatic A/C system.
A/C Flow Chart:
3. After more than 10 minutes, record the high and low pressure readings as well as the center vent temperature. Carefully follow the flow chart to correctly diagnose the vehicle condition.
Repair Procedure # 1 (Evaporator Incident)
1. Use suitable recovery equipment to recover the refrigerant as recommended in the service manual (page HA-13 for 1993; page HA-7 for 1994-97).
2. Remove the cooling unit and replace the evaporator assembly with P/N 27280-2B000.
3. Reinstall the cooling unit.
IMPORTANT: When replacing parts, observe the following:
^ Replenish refrigerant oil. Refer to page HA-21, LUBRICATION OIL - Checking and Adjusting in the 1993 service manual. Refer to page HA-138, SERVICE PROCEDURES - Maintenance of Oil Quantity in Compressor in the 1994 service manual. Refer to the HA section under SERVICE PROCEDURES - Compressor Lubricant Quantity in the 1995 - 1997 service manuals.
^ Always replace used O-rings.
4. Evacuate, then recharge the system with 1.54-1.76 lbs (0.70-0.80 kg) of R134a refrigerant.
5. Conduct a leak check and an A/C performance test to ensure proper repair.
Repair Procedure # 2 (Loose Desiccant Incident)
1. Use suitable recovery equipment to recover the refrigerant as recommended in the service manual.
2. Remove the following (see Figure 1):
^ Liquid tank
^ High cooler pipe (from the liquid tank outlet to evaporator inlet)
^ Evaporator inlet tube
^ Expansion valve.
NOTE: The high cooler pipe could be a one or two piece pipe depending on whether the A/C was factory- or kit-installed. The service replacement part for the high cooler pipe contains two pieces for ease of installation.
3. Replace all removed parts with new parts. Torque all joint fittings (see Figure 1).
IMPORTANT: When replacing parts, observe the following:
^ Replace all parts mentioned in step 2 at the same time because the loose desiccant may settle anywhere along this section when the A/C system is off.
^ Replenish refrigerant oil. Refer to page HA-21, LUBRICATION OIL - Checking and Adjusting in the 1993 service manual. Refer to page HA-138, SERVICE PROCEDURES - Maintenance of Oil Quantity in Compressor in the 1994 service manual. Refer to the HA section under SERVICE PROCEDURES - Compressor Lubricant Quantity in the 1995 - 1997 service manuals.
^ Properly install both expansion valve insulation wraps with new parts.
^ Always replace used O-rings.
4. Evacuate, then recharge the system with 1.54-1.76 lbs (0.70-0.80 kg) of R134a refrigerant.
5. Conduct a leak check and an A/C performance test to ensure proper repair.
PARTS INFORMATION
CLAIMS INFORMATION
When applicable, standard claims coding applies.