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AC not working properly

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    Topic
  • #491578
    Martin JacobMartin Jacob
    Participant

      Im having problems with my Mitsubishi Lancers AC for quite a lot of time . Lots of mechanics have messed with it . Every time the vehicle is out of the work shop it will work for some time. Here is some thing i noticed ..

      When I push on the Air conditioning

      1. If the AC is working the RPM will remain below 1k

      2.If its not working RPM will reach 1.1k

      One more thing i have noticed .. During running/Idling the AC just works for some time. That time the RPM will oscillate between 900 to 1100 .

      In the starting of a trip the AC will be working but after some time it fails . Any idea about what could be wrong with my Car

    Viewing 11 replies - 1 through 11 (of 11 total)
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    • #491587
      davedave
      Participant

        low pressure will mess with your idle. i experienced this on my own vehicle; when the pressure was low, the car would oscillate the idle.

        i would get a high and low side reading of your system pressure and start there.

        #491922
        Martin JacobMartin Jacob
        Participant

          i have given it to mechanic and he says the whole system was a chaos . And he has asked me to replace

          1.Gas – because the it will escape during the repair process
          2.Compressor Oil
          3.O ring
          4.Pipe valve
          5. C valve
          6.Thermostat Switch {
          7. Compressor sensor{ Direct connection to the Ac was given with out the sensor.
          8.Cooling Oil

          146.82 US Dollar is what he billed me .

          #492162
          davedave
          Participant

            $146 isn’t bad for all that A/C work; however, i would get a second opinion… seems kinda wierd that all those sensors, switches and what not would all go out at the same time.

            #492255
            Martin JacobMartin Jacob
            Participant

              AC`s working has been wonky for some time .. about 1.5yrs . Different mechanics have given different diagnosis and have replaced different things.

              First it started with the blower not blowing air if AC is used for a long time . Then if the AC is switched off the blower would start blowing air again.

              #492263
              davedave
              Participant

                q: what is the year/make/model/engine & number of miles on your vehicle?

                I’ll try to pull up the schematic of your system and provide real possibilities as opposed to all these different hack ideas.

                I’d love to get my hands on this btw, i like a challenge.

                #492265
                Martin JacobMartin Jacob
                Participant

                  Year : 2000
                  Make : Mitsubishi
                  Number of miles: 200000

                  http://www.mitsubishi-motors.co.in/lancer/specs.php
                  http://www.gaadi.com/Mitsubishi-Lancer-Diesel-Specification

                  Is this the kind of spec you need ??

                  #492330
                  davedave
                  Participant

                    GENERAL DESCRIPTION

                    The heater system uses a two-way-flow full-air-mix system that features high performance and low operating noise. It includes an independent face air blowing function. In addition, an air purifier has been included.

                    OPERATION

                    CONDENSER FAN AND RADIATOR FAN CONTROL
                    For the operation of each fan, refer to Diagnosis – Symptom Chart.

                    COMPRESSOR CONTROL

                    When operating the air conditioning switch

                    The air thermo sensor, which senses the temperature of the air flowing out of the evaporator, deactivates the compressor at 5 °C (41.0 °F) or below.
                    The dual pressure switch turns OFF when the refrigerant pressure becomes excessively high or low, thus protecting the compressor circuit.
                    When the air thermo sensor is activated, the dual pressure switch is ON, and the ignition switch, blower switch, and air conditioning switch are ON, the A/C compressor relay is energized.

                    A/C Compressor Relay ON Conditions

                    When operating the air outlet changeover control knob
                    When the air outlet changeover control knob is moved to DEFROSTER or DEFROSTER/FOOT position, the defroster switch, which is connected in series to the air conditioning switch, is turned on. The other compressor control than the above is the same as that when operating the air conditioning switch.

                    Idle-Up Operation Check

                    Before inspection and adjustment, set vehicle in the following condition:
                    Engine coolant temperature: 80 – 90 °C (176.0 – 194.0 °F)
                    Lights, electric cooling fan and accessories: Set to OFF
                    Transmission: Neutral (“N” or “P” for vehicles with A/T)
                    Steering wheel: Straightforward
                    Check whether or not the idle speed is the standard value. Refer to On-vehicle Service – Basic Idle Speed Adjustment. Standard value: 700 ±100 r/min
                    When the A/C is running after turning the A/C switch to ON, and the blower switch to the 3(MH) or 4(HI) position, check to be sure that the idle speed is at the standard value. Standard value: 850 ±100 r/min NOTE: The engine control module /the powertrain control module determines whether the A/C load is low or high according to the output signal from the automatic compressor controller. NOTE: It is not necessary to make an adjustment, because the idling speed is automatically adjusted by the ISC system. If, however, a deviation from the standard value occurs for some reason, check the ISC system. NOTE: Check 4 minutes after idling begins.

                    Technical Service Bulletins

                    05-55-004 12/01/2005 A/C – Poor Heater Performance in Extreme Cold
                    05-55-003 12/01/2005 A/C – Temperature Knob Hard to Turn
                    04-55-008 09/01/2004 A/C – Water Leaks to The Interior
                    03-51-001 01/01/2003 A/C – Blower Motor Failure
                    02-55-005 07/01/2002 A/C – Musty/Moldy Odors In Passenger Compartment

                    #493629
                    EricTheCarGuy 1EricTheCarGuy
                    Keymaster

                      This type of thing is almost impossible to deal with via the forum. This is the type of thing we need to get our hands on. For that reason I might suggest taking it to a new place to be diagnosed. That said I’m wondering if the AC is actually working during your idle issues. If it isn’t then perhaps there’s in input problem. Many of these functions are tied into the ECU. if the ECU is getting bad information or has a problem of it’s own it won’t be able to control the AC operation properly. This is further complicated by the fact it could also be a wiring issue. I’m sure you’re beginning to see why this can get complicated.

                      #493712
                      Martin JacobMartin Jacob
                      Participant

                        We had the wiring insulated about two months ago .
                        This is the 4th mechanic , all of them give different opinion and fix different things . After fixing the car will run for some 2000/ 3000 km and the AC will break again .

                        if the ECU is getting bad information or has a problem of it’s own it won’t be able to control the AC operation properly: How can i check if the ECU is running properly ?

                        The working of AC in idle is different in different times , mostly from a cold start it will work for some time and fail . Some times after some time of idling the AC will go into a on-off situation .. you can see the RPM meter switching from 900 rpm to 1100 rpm . This happens during riding also , you can actually feeling the vehicle jumping forward.

                        What the last mechanic has said is that
                        1. When he inspected the compressor , he found that the compressor oil was of very low quality .
                        2. The connection to the AC was given by passing temperature sensor and the thermostat .So the AC was working all the time with out cutting off.
                        3. The was leaks from the valves.
                        4. He also said he will quit the job if the AC fails again .

                        #494228
                        davedave
                        Participant

                          I’ve been thinking about this, and I think the best way to approach this problem would be to plug in a scan tool and see what sensors are lying to the ECU and PCU.

                          #495676
                          EricTheCarGuy 1EricTheCarGuy
                          Keymaster

                            The fact that you’ve had so many opinions on this already is clouding the issue. You need someone to step in that knows what they’re doing to cut through the speculation and actually do some real diagnostic work. To me it sounds like much of what you’ve been told up to this point is a guess. As I said in my last post this is very difficult for some of us on the forum to help with without actually seeing the vehicle for ourselves. Keep us posted no matter what.

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