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2006 Saturn Vue cooling at idle

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  • 2006 Saturn Vue cooling at idle

    2006 Saturn Vue 3.5 V6. Over the last 2 years the A/C would cool fine going down the road and immediately stop cooling at a stop. I replaced the compressor, condenser, drier and evap. Pulled a vacuum, no leaks charged with 28 oz. At idle vent temp is 70 F, low side is 57 high side is 180 with outside temp at 87. At 3K rpm vent temp drops to 57, low side 38, high side 210ish. I've checked relays, fuses, wires, fans and I got nothing. It's been in 2 different shops that were no help. I've had this thing apart 3 times over the last 2 months trying to fix it. What am I missing?

  • #2
    Poor cooling at idle or slow speed with good cooling at high speed is almost always poor heat transfer at the condenser. Either air is going around rather than thru, or there is poor thermal bond between the fins and tubes or the fan is not drawing enough air over it at low speed to get the heat out of the refrigerant.
    1 st test is to mist the condenser with a garden hose while watching the pressures and temps, they should improve dramatically if that is the problem.
    I am slightly concerned that the high side isn't higher with poor heat rejection, I am not sure of the amount of refrigerant that system requires, so I take your word on it being correct. A slipping belt or clutch is something else I would look for.
    Last edited by Cornbinder89; 4 weeks ago.

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    • #3
      ?? Good one. Right everything no cool it wouldn't with those pressures. Guess of the moment is heat contamination - maybe? Try this: Pinch off hose* to heater core if hose pliable enough (watch that hose later not good for them) see what changes. It might so just maybe evaporator job didn't seal well or duct doors not working properly to blend and isolate one from the other. Return refrigerant could be just too hot to condense to a liquid getting such poor results.
      * Warning there: Heater cores are sometimes also doubling as a by-pass hose for engine coolant circulation. Limit doing that to just tests or risk overheating engine away from the water pump will not circulate coolant well or enough for it! Beware of that,
      Tom
      MetroWest, Boston

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      • #4
        Originally posted by Cornbinder89 View Post
        Poor cooling at idle or slow speed with good cooling at high speed is almost always poor heat transfer at the condenser. Either air is going around rather than thru, or there is poor thermal bond between the fins and tubes or the fan is not drawing enough air over it at low speed to get the heat out of the refrigerant.
        1 st test is to mist the condenser with a garden hose while watching the pressures and temps, they should improve dramatically if that is the problem.
        I am slightly concerned that the high side isn't higher with poor heat rejection, I am not sure of the amount of refrigerant that system requires, so I take your word on it being correct. A slipping belt or clutch is something else I would look for.
        i'll mist the condenser tonight and see what happens. I put a new belt and compressor on it and doesn't appear to be slipping. I added 1.75lb of refrig as indicated under the hood. Thank you for the replies.

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        • #5
          Originally posted by Tom Greenleaf View Post
          ?? Good one. Right everything no cool it wouldn't with those pressures. Guess of the moment is heat contamination - maybe? Try this: Pinch off hose* to heater core if hose pliable enough (watch that hose later not good for them) see what changes. It might so just maybe evaporator job didn't seal well or duct doors not working properly to blend and isolate one from the other. Return refrigerant could be just too hot to condense to a liquid getting such poor results.
          * Warning there: Heater cores are sometimes also doubling as a by-pass hose for engine coolant circulation. Limit doing that to just tests or risk overheating engine away from the water pump will not circulate coolant well or enough for it! Beware of that,
          thank you I'll give it try. To me it doesn't appear that the fans are pulling enough air to cool the condenser, thus the temp change going down the road, but both fans are working?

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          • #6
            You did lot bear with me searching mind for the odd reasons: Another is with all that some reports (not to me yet) of fans working backwards! YES - blowing OUT thru grille isn't going to cut it.

            ? How could you make that mistake? Not always sure but know some relays do not all power rather are grounding that circuit to work power is and was there. Don't mind that just look and see. Also with everything OFF and no chance a fan will start up - engine off and use gloves that could take it spin fans if you can see if they can coast? If not why not?

            Should be free when not in use I really can't say all if not needed some fan type things that passively turn are slowing air motion of moving along like a helicopter with lost engine those are a brake in a free fall TMK if locked would drop like a rock - right?

            Lots of thought goes into this stuff but on the list to check so far in the rare side of why poor results just think of the odd things,
            Tom
            MetroWest, Boston

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