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AC Clutch does not cycle with the AC on

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  • Cusser
    replied
    Originally posted by OuThere View Post
    2002 Nissan Sentra 1.8L
    10. when i drive after about 10-15 minutes the coolant temp will start to spike. thinking with the compressor always on maybe a big load on the motor. Even on the highway around 70mph which i am sure the fans have little effect the coolant temp will spike.
    1. Bleed ALL the air out of the cooling system

    2. Have you replaced the thermostat?

    3. Is your radiator 20 years old?

    4. Does the temperature gauge go into the red/danger area, or just reads higher than it did?

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  • Tom Greenleaf
    replied
    Missed notice so quote from top post: ">10 when i drive after about 10-15 minutes the coolant temp will start to spike.<"

    That could be the whole issue? I couldn't know each set up but many vehicles will keep fan(s) on while A/C is in request mode. If engine temp is getting high to too high take care of that! No engine, no A/C!

    Cornbinder mentioned dirt/debris in condenser or in between unseen need to look if none you need to dive into this temp spike issue. Yes, some will fluctuate but be about the same A/C requested or not others A/C forcing fans (not all do for all times) will bring engine temp down.

    If radiator is hot from engine it can "radiate" heat backwards - assorted shapes of vehicles and conditions out there.

    First make sure the lower spoiler (air dam) is in place not missing. It creates a relative vacuum under engine is where air flow thru grille goes. If is pressure there it's totally possible the airflow is reduced while driving along.

    There isn't one part that is there just for good looks it has a real purpose.

    If you misted condenser with hose water while just holding a raised idle that would be the absolute best performance the car could do as measure (get one) a thermo in center vent of dash panel outlets expect to hover in or around 42-45F is the best it should do not lower not lots higher without wild weather extremes 100F for real or more.

    It's a 20 year old car +/- now expect some quirks but doesn't have to be that bad.

    Other! If this thing has a cabin air filter replace if dirty or toss it on some is your call if so for where you are and use car the most,

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  • Cornbinder89
    replied
    Pressure is a function of temp only. As long as there is enough refrigerant to condense, the high side pressure will reflect the condensing temp.
    There are many "rule of thumb" but as long as your gauge is accurate, what you see , is what it is.
    185 psi is 125 deg condensing temp. Without knowing the air temp passing through the condenser (not what the thermometer shows on your house, or what the radio say) actual air temp right before the condenser, I can't say if it is good or bad.
    Another rule of thumb is 30-40 degs above the air passing though the condenser is acceptable for an air cooled condenser. You are in the ballpark if the air passing it is 85 deg.
    I would hope to see the low side a little lower, but if you measured on a scale, how much you put in, then that is the best way and refrigerant amount is not the problem.
    If you had air (non condensable) your high side would be higher.
    Make sure the condenser, radiator and evaporator fins aren't clogged. Also check and replace a intake air filter if you car uses one.
    Engine temp is unrelated to A/C, you have an engine cooling problem that the A/C makes worse but is not the source. A few degs warmer and you still get the coolant light on even if the A/C wasn't in use..
    R134a pressure/temp chart is here
    R-134a vs R12 Temp Pressure Chart - Automotive Air Conditioning Bulletin Board
    Tx systems don't cycle off unless the evaporator temp drops to the frost point if a frost switch is used. If an evaporator pressure control is used, they NEVER cycle.
    Last edited by Cornbinder89; 06-01-2022, 10:51 AM.

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  • Tom Greenleaf
    replied
    Noticed first you are at Carjunky forums also and frustrated. This is a TXV system cycling is slower to not at all depending on a list of factors.
    CCOT mentioned there means "Clutch Cycling Orifice Tube" system this is NOT that type.

    Just FYI, fans are or are not need at speed of car based on usually high side readings as computer controlled would drop with nobody there to see it. If not they come on at any speed some models air isn't enough at speed - shape of vehicle etc.

    For now it's too general but your high side is too low for temps most people would want A/C at all. Wildly general it would be 2.5X the temp coming thru grill not the weather forecast of what it is. Note that, the car doesn't care it's that time and moment with any reason it's hotter than forecasts or local thermo where you are observing it- OK?

    Leave a comment:


  • OuThere
    started a topic AC Clutch does not cycle with the AC on

    AC Clutch does not cycle with the AC on

    2002 Nissan Sentra 1.8L
    1. replaced the low side hose from evap to the compressor was leaking
    2. pulled a vacuum
    3. filled with R134A refrigerant using a scale and of course a manifold set
    4. the coolant temp is a little below halfway w/o the AC on
    5. with the AC on both fans come on
    6. AC clutch never seems to cycle. watched it for 15 minutes. just stays on
    7. Getting Ice cold air with the AC on
    8. using one of those free service manuals from the Nissan owners forums. Have found a lot of mistakes although better than nothing, says at 85° the low should be around low 30's high should be around 180-195 psi. sounds kind of low for both. could someone check that I tried googling.
    9. low side around 32psi, high side starts at around 150psi will after a few get to 185psi
    10 when i drive after about 10-15 minutes the coolant temp will start to spike. thinking with the compressor always on maybe a big load on the motor. Even on the highway around 70mph which i am sure the fans have little effect the coolant temp will spike.
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