94 Mazda B2300; AC extreme high pressure issue

Discussion in 'Mazda Truck Forum' started by trolleytrooper, Sep 19, 2015.

  1. trolleytrooper

    trolleytrooper Full Member

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    Low cabin cooling temp became an issue and proceeded to get worse until no cooling at all. Discovered the clutch fell off a new (not rebuilt) compressor. Under warranty so did the replacement as well as the dryer and low pressure switch. Pulled vacuum for .5 - .75 hr. then recharged weighing out 134A and clutch cycled during process until reaching 22 oz. then watched my gauges start to climb. Low pressure side stopped @ "normal". Hi side should have cycled the clutch off @ about 250 psi but did not and continued climbing to 350 psi before I turned off the system. Changed the hi pressure switch today and ran another test with the same results. If caused by a blockage, where is the most likely place for that to occur and how to go about testing? If not, I'd appreciate suggestions.
     
  2. chevychase

    chevychase Semi-Admin
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    Did you change the orfice tube? should change..usually will not warranty if not..it can get clogged. click here
     
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  3. trolleytrooper

    trolleytrooper Full Member

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    #3 trolleytrooper, Sep 20, 2015
    Last edited: Sep 20, 2015
    Thanks for the reply and yes, along with the dryer. Been working on this for most of a hot summer and wondering if this issue may be electrical, first and maybe a blockage secondly. A couple things puzzle me; one is that since changing out the original compressor I've notice lately that the engine rpm does not increase when ac turned on and secondly the hi pressure switch not cycling the clutch. Could the ECC be defective? BTW, during yesterday's test the center vent air temp was 60 degrees when I shut the ac off.
     
  4. chevychase

    chevychase Semi-Admin
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    What is ecc? Think maybe a relay ? I have found out this about mazdas..if you search..search for 94 ford ranger ac ..instead of mazda..get more results..same trucks.
    I will find you a diagram...if i can.
     
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  5. trolleytrooper

    trolleytrooper Full Member

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    Sorry....ecc = engine control computer. Will give the ranger suggestion a try, thanks and I have a copy of the elect schematic. Was wondering if any others had similar situation. Oh, replaced the relay when first noticing the ac/idle issue - no change.
     
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  6. trolleytrooper

    trolleytrooper Full Member

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    Update. Viewed a couple YouTube AC diagnostic videos since last post along with the AC elect. schematic. The author of the schematic was kind enough to include some pertinent info next to various parts of the AC system regarding how they functioned. It was noted next to the low pressure switch that it may not work properly if the motor rpm was too low. After pondering that for a moment I remembered that a fella in one of the videos suggested placing a piece of credit cart thickness plastic between the accelerator linkage and the idle adjustment screw. Since the idle speed wasn't increasing automatically when the AC was turned on this hint may be helpful....and it was! The clutch started cycling and the gauges were indicating pressure cycles were within tolerances. When the plastic strip was removed the rpm slowed and the clutch stopped cycling again indicating the idle issue is not resolved. So, I'm guessing the ecc (aka as the engine control computer, powertrain control module or PCM) may the culprit. Any other suggestions are greatly appreciated.
     
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